Photosynthetic light reactions increase total lipid accumulation in carbon-supplemented batch cultures of Chlorella vulgaris.

Microalgae are an attractive biofuel feedstock because of their high lipid to biomass ratios, lipid compositions that are suitable for biodiesel production, and the ability to grow on varied carbon sources. While algae can grow autotrophically, supplying an exogenous carbon source can increase growth rates and allow heterotrophic growth in the absence of light. Time course analyses of dextrose-supplemented Chlorella vulgaris batch cultures demonstrate that light availability directly influences growth rate, chlorophyll production, and total lipid accumulation. Parallel photomixotrophic and heterotrophic cultures grown to stationary phase reached the same amount of biomass, but total lipid content was higher for algae grown in the presence of light (an average of 1.90 mg/mL vs. 0.77 mg/mL over 5 days of stationary phase growth).

Context-conditioned generalization in adaptation to distorted speech.

People were trained to decode noise-vocoded speech by hearing monosyllabic stimuli in distorted and unaltered forms. When later presented with different stimuli, listeners were able to successfully generalize their experience. However, generalization was modulated by the degree to which testing stimuli resembled training stimuli: Testing stimuli's consonants were easier to recognize when they had occurred in the same position at training, or flanked by the same vowel, than when they did not. Furthermore, greater generalization occurred when listeners had been trained on existing words than on nonsense strings. We propose that the process by which adult listeners learn to interpret distorted speech is akin to building phonological categories in one's native language, a process where categories and structure emerge from the words in the ambient language without completely abstracting from them.