Entropy inference and the James-Stein estimator, with application to nonlinear gene association networks

We present a procedure for effective estimation of entropy and mutual information from small-sample data, and apply it to the problem of inferring high-dimensional gene association networks. Specifically, we develop a James-Stein-type shrinkage estimator, resulting in a procedure that is highly efficient statistically as well as computationally. Despite its simplicity, we show that it outperforms eight other entropy estimation procedures across a diverse range of sampling scenarios and data-generating models, even in cases of severe undersampling. We illustrate the approach by analyzing E. coli gene expression data and computing an entropy-based gene-association network from gene expression data. A computer program is available that implements the proposed shrinkage estimator.Comment: 18 pages, 3 figures, 1 tabl

Review article

In eukaryotic cells, the trans-Golgi network (TGN) serves as a platform for secretory cargo sorting and trafficking. In recent years, it has become evident that a complex network of lipid-lipid and lipid-protein interactions contributes to these key functions. This review addresses the role of lipids at the TGN with a particular emphasis on sphingolipids and diacylglycerol. We further highlight how these lipids couple secretory cargo sorting and trafficking for spatiotemporal coordination of protein transport to the plasma membrane

Swiss teenagers, AIDS and sexually transmitted diseases: presentation and evaluation of a preventive exhibition

As part of a larger school-based health program for Swiss apprentices and students, an AIDS and sexually transmitted disease (STD) prevention exhibition was offered to 7000 boys and girls aged 15-19. Its objectives were: (1) to reinforce their knowledge of STD and AIDS transmission and prevention, and (2) to modify their attitudes and behavior regarding (a) the decision whether, when and how to have sex and (b) the use of condoms. The exhibition consisted of six posters, reviewed by specially-trained teachers and nurses. Condoms were presented in an amusing way and were freely available. A case control follow-up survey was carried out 12 weeks later in two random samples: 798 subjects from an experimental school and 600 subjects from a control school completed an anonymous multiple-choice questionnaire. Of the respondents, 69% were sexually active, and among this group, 76% of the boys and 59% of the girls had used a condom at least once but only 15% used them regularly. As regards knowledge, both groups reached high levels (75-97% of right answers); the group exposed to the exhibition scored higher for only two items (P < 0.05). Significantly more teenagers in the experimental group said they had handled condoms or had condoms with them ‘just in case ...'. This evaluation shows that an AIDS and STD prevention exhibition for teenagers may be both feasible and effective. However, future intervention programs should include practical interpersonal counseling on topics such as mutual trust, contraception issues, and the purchase and use of condom