Search

Online sponsored search advertising has emerged as the dominant online advertising format largely because of their pay-for-performance nature, wherein advertising expenditures are closely tied to outcomes. While the pay-for-performance format substantially reduces the wastage incurred by advertisers compared to traditional pay-per-exposure advertising formats, the reduction of such wastage also carries the risk of reducing the signaling properties of advertising. Lacking a separating equilibrium, low-quality firms in these markets may be able to mimic the advertising strategies of high-quality firms. This study examines this issue in the context of online sponsored search markets. Using data gathered from sponsored search auctions for keywords in a market without intervention by the intermediary, we find evidence of adverse selection for products/services characterized by high uncertainty. On the other hand, there is no evidence of adverse selection for similar products in a regulated sponsored search market, suggesting that intervention by the search intermediary can have a significant impact on market outcomes and consumer welfare. Key words: electronic commerce; competitive impacts of IS; IT impacts on industry and market structure; econometrics History: Sanjeev Dewan, Senior Editor; Rahul Telang, Associate Editor. This paper was received on October 14, 2006, and was with the authors 12 months for 3 revisions. Published online in Articles in Advance June 12, 2009., 1. Introduction Sponsored search mechanisms, where advertisers bid for better placement in the listing of search results on services such as Yahoo! and Google, have emerged as the dominant revenue [...]

A fundamental problem in systems biology and whole genome sequence analysis is how to infer functions for the many uncharacterized proteins that are identified, whether they are conserved across organisms of different phyla or are phylum-specific. This problem is especially acute in pathogens, such as malaria parasites, where genetic and biochemical investigations are likely to be more difficult. Here we perform comparative expression analysis on Plasmodium parasite life cycle data derived from P. falciparum blood, sporozoite, zygote and ookinete stages, and P. yoelii mosquito oocyst and salivary gland sporozoites, blood and liver stages and show that type II fatty acid biosynthesis genes are upregulated in liver and insect stages relative to asexual blood stages. We also show that some universally uncharacterized genes with orthologs in Plasmodium species, Saccharomyces cerevisiae and humans show coordinated transcription patterns in large collections of human and yeast expression data and that the function of the uncharacterized genes can sometimes be predicted based on the expression patterns across these diverse organisms. We also use a comprehensive and unbiased literature mining method to predict which uncharacterized parasite-specific genes are likely to have roles in processes such as gliding motility, host-cell interactions, sporozoite stage, or rhoptry function. These analyses, together with proteinprotein interaction data, provide probabilistic models that predict the function of 926 uncharacterized malaria genes and also suggest that malaria parasites may provide a simple model system for the study of some human processes. These data also provide a foundation for further studies of transcriptional regulation in malaria parasites. [ABSTRACT FROM AUTHOR]

The genetic background of a patient determines in part if a person develops a mild form of malaria and recovers, or develops a severe form and dies. We have used a mouse model to detect genes involved in the resistance or susceptibility to Plasmodium berghei malaria infection. To this end we first characterized 32 different mouse strains infected with P. berghei and identified survival as the best trait to discriminate between the strains. We found a locus on chromosome 6 by linking the survival phenotypes of the mouse strains to their genetic variations using genome wide analyses such as haplotype associated mapping and the efficient mixed-model for association. This new locus involved in malaria resistance contains only two genes and confirms the importance of Ppar-gamma in malaria infection.