Search

Prasinophytes are widespread marine algae for which responses to nutrient limitation and viral infection are not well understood. We studied the picoprasinophyte, Micromonas pusilla, grown under phosphate‐replete (0.65 ± 0.07 d−1) and 10‐fold lower (low)‐phosphate (0.11 ± 0.04 d−1) conditions, and infected by the phycodnavirus MpV‐SP1. Expression of 17% of Micromonas genes in uninfected cells differed by >1.5‐fold (q < 0.01) between nutrient conditions, with genes for P‐metabolism and the uniquely‐enriched Sel1‐like repeat (SLR) family having higher relative transcript abundances, while phospholipid‐synthesis genes were lower in low‐P than P‐replete. Approximately 70% (P‐replete) and 30% (low‐P) of cells were lysed 24 h post‐infection, and expression of ≤5.8% of host genes changed relative to uninfected treatments. Host genes for CAZymes and glycolysis were activated by infection, supporting importance in viral production, which was significantly lower in slower growing (low‐P) hosts. All MpV‐SP1 genes were expressed, and our analyses suggest responses to differing host‐phosphate backgrounds involve few viral genes, while the temporal program of infection involves many more, and is largely independent of host‐phosphate background. Our study (i) identifies genes previously unassociated with nutrient acclimation or viral infection, (ii) provides insights into the temporal program of prasinovirus gene expression by hosts and (iii) establishes cell biological aspects of an ecologically important host‐prasinovirus system that differ from other marine algal‐virus systems.

This technical report is the user manual for a soil moisture downscaling tool that is implemented in ArcGIS. The software consists of DownscaleConcept.exe, an executable file developed from Matlab, and a GIS tool for running DownscaleConcept, DoConGIS, which is used from within ArcGIS. DownscaleConcept was developed to estimate soil moisture at a fine resolution based on coarser, spatial soil moisture estimates by considering terrain characteristics such as slope, aspect, and contributing area., The original document contains color images.

Propulsion systems based on the pulsed detonation cycle offer the potential to provide increased performance while simultaneously reducing engine weight, cost, and complexity, relative to conventional propulsion systems currently in service. The increased performance potential is due to the high thermodynamic efficiency of detonation combustion. The near constant volume heat addition process of the detonation cycle, along with the lack of a compression cycle lend to the high efficiency and specific impulse, simplicity, and low-cost of pulse detonation propulsion systems. Pulse detonation Engines (PDEs) have the potential for operation at speeds ranging from static to high-supersonic (M<5), with competitive efficiencies enabling supersonic operation beyond conventional gas turbine engine technology. Currently, no single engine cycle exists that has such a broad range of operability. Pulse Detonation Rocket Engines (PDREs) have the potential to drastically reduce the cost of upper stage and orbit-transfer propulsion systems, and are also attractive for lunar and planetary exploration, and landers and excursion vehicles that require throttling for soft landing. This report discusses the thermodynamic basis of pulse detonation propulsion technology and identifies the major technology initiatives currently underway in the United States.