Thomas DuBois

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As user-generated content and interactions have overtaken the web as the default mode of use, questions of whom and what to trust have become increasingly important. Fortunately, online social networks and social media have made it easy for users to indicate whom they trust and whom they do not. However, this does not solve the problem since each user is(More)
Synthesis of the major toxin proteins of the diarrheal pathogen, Clostridium difficile, is dependent on the activity of TcdR, an initiation (sigma) factor of RNA polymerase. The synthesis of TcdR and the activation of toxin gene expression are responsive to multiple components in the bacterium's nutritional environment, such as the presence of certain(More)
The major virulence factors of Clostridium difficile are toxins A and B. These toxins are encoded by tcdA and tcdB genes, which form a pathogenicity locus (PaLoc) together with three additional genes that have been implicated in regulation (tcdR and tcdC) and secretion (tcdE). To date, the PaLoc has always been found in the same location and is replaced in(More)
The World Wide Web has transformed into an environment where users both produce and consume information. In order to judge the validity of information, it is important to know how trustworthy its creator is. Since no individual can have direct knowledge of more than a small fraction of information authors, methods for inferring trust are needed. We propose(More)
While tissue culture (TC) technology for vegetative plant propagation is gradually gaining in importance in Africa, rigorous ex post assessments of welfare effects for smallholder farm households is lacking. Using recent survey data and accounting for self-selection in technology adoption, we analyze the impacts of TC banana technology on household income(More)
We analyze yield effects of tissue culture (TC) banana technology in the Kenyan small farm sector, using recent survey data and an endogenous switching regression approach. TC banana plantlets, which are free from pests and diseases, have been introduced in East Africa since the late-1990s. While field experiments show significant yield advantages over(More)
The pathogenicity of Clostridium difficile is linked to its ability to produce two toxins: TcdA and TcdB. The level of toxin synthesis is influenced by environmental signals, such as phosphotransferase system (PTS) sugars, biotin, and amino acids, especially cysteine. To understand the molecular mechanisms of cysteine-dependent repression of toxin(More)
Many networks arise in a random and distributed fashion, and yet result in having a specific type of degree structure: e.g., the WWW, many social networks, biological networks, etc., exhibit power-law, stretched exponential, or similar degree structures. Much work has examined how a graph's degree-structure influences other graph properties such as(More)