This paper investigates whether and how the disclosure tone of earnings conference calls predicts future stock price crash risk. Using US public firms' conference call transcripts from 2010 to 2015, we find that firms with less optimistic tone of year-end conference calls experience higher stock price crash risk in the following year. Additional analyses reveal that the predictive power of tone is more pronounced among firms with better information environment and lower managerial equity incentives, suggesting that extrinsic motivations for truthful disclosure partially explain the predictive power of conference call tone. Our results shed light on the long-term information role of conference call tone by exploring the setting of extreme future downside risk, when managers have conflicting incentives either to unethically manipulate disclosure tone to hide bad news or to engage in ethical and truthful communication.
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Background
Isobutanol is an attractive biofuel with many advantages. Third-generation biorefineries that convert CO2 into bio-based fuels have drawn considerable attention due to their lower feedstock cost and more ecofriendly refining process. Although autotrophic cyanobacteria have been genetically modified for isobutanol biosynthesis, there is a lack of stable and convenient strategies to improve their production.
Results
In this study, we first engineered Synechococcus elongatus for isobutanol biosynthesis by introducing five exogenous enzymes, reaching a production titer of 0.126 g/L at day 20. It was then discovered that high salinity stress could result in a whopping fivefold increase in isobutanol production, with a maximal in-flask titer of 0.637 g/L at day 20. Metabolomics analysis revealed that high salinity stress substantially altered the metabolic profiles of the engineered S. elongatus. A major reason for the enhanced isobutanol production is the acceleration of lipid degradation under high salinity stress, which increases NADH. The NADH then participates in the engineered isobutanol-producing pathway. In addition, increased membrane permeability also contributed to the isobutanol production titer. A cultivation system was subsequently developed by mixing synthetic wastewater with seawater to grow the engineered cyanobacteria, reaching a similar isobutanol production titer as cultivation in the medium.
Conclusions
High salinity stress on engineered cyanobacteria is a practical and feasible biotechnology to optimize isobutanol production. This biotechnology provides a cost-effective approach to biofuel production, and simultaneously recycles chemical nutrients from wastewater and seawater.
LANGUAGE NOTE | Document text in Chinese; abstract in English only.Professor Hans-Martin Sass highlights an important aspect of the COVID-19 situation: the virus not only hurts people, but also attacks political and corporate bodies. He argues primarily on the level of basic ontology, revolving around two claims: first, that life is interconnected, and second, that long-lasting political and corporate bodies, despite their similarities to natural organisms, are more receptive to transformation and modification. In my comments, I further explore the implications of the second claim against the background of COVID-19. I focus on the concept of embodiment and show that the way embodiment figures in our interactions with others and in our experience of the world changes as more and more online social activities are organized. Most importantly, I reflect on the very meaning of embodiment in the age of high biotechnology and artificial intelligence, namely how the concept might be enlarged and/or transformed.DOWNLOAD HISTORY | This article has been downloaded 5 times in Digital Commons before migrating into this platform.
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