Informing Science InSITE - "Where Parallels Intersect" June 2003 Paper Accepted as an Informal Paper

Computer-assisted Instruction (CAI) plays very important role in e-learning system. Distance- learning students can remotely access this kind of course material. As CAI materials are in electronic form they are subject to illegal manipulation and duplication. Therefore, there is growing need to develop robust techniques for protecting these materials. Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia for many decades. This technique can also be applied to the educational materials. In this paper, a protection scheme is proposed in which double watermarks are embedded into all still images in the CAI materials before they are distributed. Firstly, the visible watermark, e.g., university's logo, is inserted directly on image pixel's intensity to exhibit an ownership. An invisible, semi- fragile watermark is then also embedded on these watermarked images. Because of the special characteristic of the latter watermark, any attempt to change or remove the visible logo can be clearly detected. We have also developed an extraction method to reveal the secret watermarks which verify our right on the CAI materials. We have conducted experiments using different kinds of attacks on the watermarked images. The results of these experiments are discussed and conclusions presented as to the reliability and applicability of our proposed scheme

HIV and HCV prevalence among entrants to methadone maintenance treatment clinics in China: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Methadone maintenance treatment (MMT) was implemented in China since 2004. It was initiated in 8 pilot clinics and subsequently expanded to 738 clinics by the end of 2011. Numerous individual research studies have been conducted to estimate HIV and HCV prevalence among MMT clients but an overview of the epidemics in relations to MMT remains unclear. The aim of this study is to estimate the magnitude and changing trends of HIV, HCV and HIV-HCV co-infections among entry clients to MMT clinics in China during 2004-2010.</p> <p>Methods</p> <p>Chinese and English databases of literature were searched for studies reporting HIV, HCV and co-infection prevalence among MMT clients in China from 2004 to 2010. The prevalence estimates were summarized through a systematic review and meta-analysis of published literatures.</p> <p>Results</p> <p>Ninety eligible articles were selected in this review (2 in English and 88 in Chinese). Nationally, pooled prevalence of HIV-HCV and HIV-HCV co-infection among MMT clients was 6.0% (95%CI: 4.7%-7.7%), 60.1% (95%CI: 52.8%-67.0%) and 4.6% (95%CI: 2.9%-7.2%), respectively. No significant temporal trend was found in pooled prevalence estimates. Study location is the major contributor of heterogeneities of both HIV and HCV prevalence among drug users in MMT.</p> <p>Conclusions</p> <p>There was no significant temporal trend in HIV and HCV prevalence among clients in MMT during 2004–2010. Prevalence of HCV is markedly higher than prevalence of HIV among MMT clients. It is recommended that health educational programs in China promote the earlier initiation and wider coverage of MMT among injecting drug users (IDUs), especially HIV-infected IDUs.</p