LEARNING BY DOING IN AN AMBIGUOUS ENVIRONMENT

We experimentally test whether risk aversion or ambiguity aversion can explain decisions in a learning by doing game. We first measure subjects' preferences toward risk and ambiguity, and then use these measures to predict behavior in the game. We find that ambiguity averse subjects pay more often to resolve ambiguity in the game. We also find that less risk averse subjects earn more in the game. Our results, in light of a previous field study of rural farmers in a developing economy, suggest a link between ambiguity aversion and technology choice, as well as a link between risk aversion and farm profitability.

TRIALS STUDY PROTOCOL Open Access

Alcohol email assessment and feedback study dismantling effectiveness for university students (AMADEUS-1): study protocol for a randomized controlled tria

Conifers have a unique small RNA silencing signature

Plants produce small RNAs to negatively regulate genes, viral nucleic acids, and repetitive elements at either the transcriptional or post-transcriptional level in a process that is referred to as RNA silencing. While RNA silencing has been extensively studied across the different phyla of the animal kingdom (e.g., mouse, fly, worm), similar studies in the plant kingdom have focused primarily on angiosperms, thus limiting evolutionary studies of RNA silencing in plants. Here we report on an unexpected phylogenetic difference in the size distribution of small RNAs among the vascular plants. By extracting total RNA from freshly growing shoot tissue, we conducted a survey of small RNAs in 24 vascular plant species. We find that conifers, which radiated from the other seed-bearing plants ∼260 million years ago, fail to produce significant amounts of 24-nucleotide (nt) RNAs that are known to guide DNA methylation and heterochromatin formation in angiosperms. Instead, they synthesize a diverse population of small RNAs that are exactly 21-nt long. This finding was confirmed by high-throughput sequencing of the small RNA sequences from a conifer, Pinus contorta. A conifer EST search revealed the presence of a novel Dicer-like (DCL) family, which may be responsible for the observed change in small RNA expression. No evidence for DCL3, an enzyme that matures 24-nt RNAs in angiosperms, was found. We hypothesize that the diverse class of 21-nt RNAs found in conifers may help to maintain organization of their unusually large genomes