Event plumes

Juniper, S. K., Bird, D. P., Summit, M., Vong, M. P., and Baker, E. T. (1998). Bacterial and viral abundances in hydrothermal event plumes over northern Gorda Ridge. Deep Sea R s. II. Top. Stud. Oceanogr. 45, 2739-2749. 

Cowen J. P., Betram M. A., Baker G. T., Feely R. A., Massoth G. J., and Summit M. (1998) Geomicrobial transformations of manganese in Gorda Ridge event plumes. Deep-Sea Res. 

Lupton J. E., Baker E. T., and Massoth G. J. (1999b) Helium, heat and the generation of hydrothermal event plumes at mid-ocean ridges. Earth Planet. Sci. Lett. 171, 343—350. 

Because event plumes represent the sudden injection of exploitable reducing chemical substrates, as well as inhibitory constituents, they are likely to induce successional changes in the microbial community structure and activity within plume waters over time (Cowen etal., 1998). For example, in studies following the 1998 Axial Volcano eruption, abundant putative bacterial sulphur filaments were observed in August 1998 (Feely etal., 1999), though they were not initially found in plumes in February 1998 (Cowen etal., 1999). 

The massive output of microbial biomass that characterises the early stages of event plumes potentially affects, and is affected by, hydrothermal constituents like H2S, Mn2+, Fe2+, H2, CH4. These reducing substances represent important energy sources as in other hydrothermal environments. 

Step 2 Determine secondary emission plume flow rate. The plume flow rate for charging and tapping is predicted by design equations for plume flow rates (compare Section 7.5). The enclosure height is taken as the limit of plume rise. The plume rise from the open furnace before charging should also be calculated. This event is also considered as a prolonged emission. 

With a single release event, the leading edge and the center of the plume (i.e., zone of highest concentration) moves increasingly farther from the source over time. 

For any event to be accurately recorded, it must persist for the pulse time of the instrument. This time is equal either to the rise time or to the time to 100% response, depending on the design of the instrument. For accurate data from aircraft sampling plumes, for example, it is necessary to obtain rise times of a few seconds or less. This is a very fast response for an analyzer and has only recently become possible for ozone measurements. 

Smoke is composed of combustion gases, soot (solid carbon particles), and unburnt fuel. For outdoor fires, the impact of smoke is usually a secondary consideration after the heat transfer. In many circumstances, the immediate thermal threat from the fire plume (jet, pool, or flash fire) overwhelms the smoke threat, particularly for personnel in close proximity to the event. There may be circumstances where personnel are in a downwind smoke plume where there is no immediate thermal threat. As a rule-of-thumb, all people within a smoke plume may be immediately or nearly immediately affected and at risk from a life safety standpoint (be it from lack of visibility or by toxic products). 

Sequence of events in matrix-assisted laser desorption/ionization. (a) Dried mixture of analyte and matrix on sample probe inserted into backplate of ion source. (foZ) Enlarged view of laser pulse striking sample. (t>2) Matrix is ionized and vaporized by laser and transfers some charge to analyte. (b3) Vapor expands in a supersonic plume. 

Pheromones are powerful modulators of insect behavior. Since the isolation and identification of the first pheromone, (10E, 12Z)-hexadec-10,12-dien-l-ol, the sex attractant of the silk moth Bombyx mori, thousands of other insect pheromones have been identified. Our understanding of the sensory apparatus required for pheromone detection has also increased significantly. Coincidentally, B. mori was instrumental in many of these advances (see below). Volatile pheromones are detected by a specialized olfactory system localized on the antennae. The precise recognition of species-specific nuances in the structure and composition of pheromone components is essential for effective pheromone-based communication. The pheromone olfactory system of species studied so far exhibits remarkable selectivity towards the species-specific pheromone blend. Pheromones are emitted in low (fg-pg) quantities and are dispersed and greatly diluted in air plumes. Thus, pheromone olfaction systems are among the most sensitive chemosensory systems known. (Schneider et al., 1968). This chapter summarizes efforts (particularly over the past 10 years) to understand the molecular basis for the remarkable selectivity and sensitivity of the pheromone olfactory system in insects. The chapter will also outline efforts to design compounds that interfere with one or more of the early events in olfaction. 

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