ONR Tropical Cyclone Motion Research Initiative: Field Experiment Summary

The Office of Naval Research Tropical Cyclone Motion initiative is a five-year program to improve basic understanding of tropical cyclone motion. The Tropical Cyclone Motion (TCM-90) field experiment was carried out during August and September 1990. The first section of this report describes the data management plan for TCM-90, and includes descriptions of the observational systems that provided data in real-time and on a delayed basis. The second section of this report summarizes the seven Intensive Observation Periods during TCM-90. A summary of the real-time data collection also is provided to aid the reader in selecting cases for study. A more complete listing that includes delayed data will be provided about April 1991, when the production of the final analyses will begin.Prepared for: the Naval Postgraduate School Monterey, CA and the Chief of Naval Research (Code 1122MM) Arlington, VAhttp://archive.org/details/onrtropicalcyclo00elsbO&MN, Direct Funding, N0001490WFt24005N

Tentoxin Sensitivity of Chloroplasts Determined by Codon 83 of beta Subunit of Proton-ATPase

Tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. In vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (ATPase) from sensitive species. Plastid atpB genes from six closely related, tentoxin-sensitive or -resistant Nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivity. The genetic relevance of this site was confirmed in Chlamydomonas reinhardtii by chloroplast transformation. The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83. Codon 83 may represent a critical site on the beta subunit that does not compete with nucleotide binding or other catalytic activities

Controllability and Perceptual Biases of Risks and Abilities: the Case of an F-16 Cockpit

This study investigated airmen’s susceptibility to unrealistic optimism biases based on the position of control in an F-16 cockpit. Forty-seven airmen completed a questionnaire measuring their “I am above average effect” in regard to their flight ability and judgment, “below average effect” regarding their risk-taking tendencies, and unrealistic optimism about the likelihood that they would be involved in an aerial accident. The results support our main hypotheses: airmen demonstrated biased perceptions on these scales. With regard to their flight ability, pilots were more susceptible to bias than navigators. Contrary to our prediction, we did not find similar results regarding invulnerability. We discuss these results in light of controllability literature

Interdependent Nutrient Availability and Steroid Hormone Signals Facilitate Root Growth Plasticity

International audiencePlants acquire essential elements from inherently heterogeneous soils, in which phosphate and iron availabilities vary. Consequently, plants have developed adaptive strategies to cope with low iron or phosphate levels, including alternation between root growth enhancement and attenuation. How this adaptive response is achieved remains unclear. Here, we found that low iron accelerates root growth in Arabidopsis thaliana by activating brassinosteroid signaling, whereas low-phosphate-induced high iron accumulation inhibits it. Altered hormone signaling intensity also modulated iron accumulation in the root elongation and differentiation zones, constituting a feedback response between brassinosteroid and iron. Surprisingly, the early effect of low iron levels on root growth depended on the brassinosteroid receptor but was apparently hormone ligand-independent. The brassinosteroid receptor inhibitor BKI1, the transcription factors BES1/BZR1, and the ferroxidase LPR1 operate at the base of this feedback loop. Hence, shared brassinosteroid and iron regulatory components link nutrient status to root morphology, thereby driving the adaptive response