Fake medical Web sites have become increasingly prevalent. Consequently, much of the health-related information and advice available online is inaccurate and/or misleading. Scores of medical institution Web sites are for organizations that do not exist and more than 90% of online pharmacy Web sites are fraudulent. In addition to monetary losses exacted on unsuspecting users, these fake medical Web sites have severe public safety ramifications. According to a World Health Organization report, approximately half the drugs sold on the Web are counterfeit, resulting in thousands of deaths. In this study, we propose an adaptive learning algorithm called recursive trust labeling (RTL). RTL uses underlying content and graph-based classifiers, coupled with a recursive labeling mechanism, for enhanced detection of fake medical Web sites. The proposed method was evaluated on a test bed encompassing nearly 100 million links between 930,000 Web sites, including 1,000 known legitimate and fake medical sites. The experimental results revealed that RTL was able to significantly improve fake medical Web site detection performance over 19 comparison content and graph-based methods, various meta-learning techniques, and existing adaptive learning approaches, with an overall accuracy of over 94%. Moreover, RTL was able to attain high performance levels even when the training dataset composed of as little as 30 Web sites. With the increased popularity of eHealth and Health 2.0, the results have important implications for online trust, security, and public safety.
In an increasingly global research landscape, it is important to identify the most prolific researchers in various institutions and their influence on the diffusion of knowledge. Knowledge diffusion within institutions is influenced by not just the status of individual researchers but also the collaborative culture that determines status. There are various methods to measure individual status, but few studies have compared them or explored the possible effects of different cultures on the status measures. In this article, we examine knowledge diffusion within science and technology-oriented research organizations. Using social network analysis metrics to measure individual status in large-scale coauthorship networks, we studied an individual's impact on the recombination of knowledge to produce innovation in nanotechnology. Data from the most productive and highimpact institutions in China (Chinese Academy of Sciences), Russia (Russian Academy of Sciences), and India (Indian Institutes of Technology) were used. We found that boundary-spanning individuals influenced knowledge diffusion in all countries. However, our results also indicate that cultural and institutional differences may influence knowledge diffusion.
Social networks evolve over time with the addition and removal of nodes and links to survive and thrive in their environments. Previous studies have shown that the linkformation process in such networks is influenced by a set of facilitators. However, there have been few empirical evaluations to determine the important facilitators. In a research partnership with law enforcement agencies, we used dynamic social-network analysis methods to examine several plausible facilitators of co-offending relationships in a large-scale narcotics network consisting of individuals and vehicles. Multivariate Cox regression and a two-proportion z-test on cyclic and focal closures of the network showed that mutual acquaintance and vehicle affiliations were significant facilitators for the network under study.We also found that homophily with respect to age, race, and gender were not good predictors of future link formation in these networks. Moreover, we examined the social causes and policy implications for the significance and insignificance of various facilitators including common jails on future co-offending. These findings provide important insights into the link-formation processes and the resilience of social networks. In addition, they can be used to aid in the prediction of future links. The methods described can also help in understanding the driving forces behind the formation and evolution of social networks facilitated by mobile and Web technologies.
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