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Search: authors:"John J. Cullen"

4 papers found.
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Enumerating viable phytoplankton using a culture-based Most Probable Number assay following ultraviolet-C treatment

Ballast water management systems (BWMS) must be tested to assess their compliance with standards for the discharge of organisms, for example in the ≥ 10- and < 50-μm size category, which is dominated by phytoplankton. Assessment of BWMS performance with the vital stains fluorescein diacetate + 5-chlorofluorescein diacetate, required by regulations in the USA, is problematic in...

On the use of the serial dilution culture method to enumerate viable phytoplankton in natural communities of plankton subjected to ballast water treatment

Discharge standards for ballast water treatment (BWT) systems are based on concentrations of living cells, for example, as determined with vital stains. Ultraviolet radiation (UV) stops the reproduction of microorganisms without killing them outright; they are living, but not viable, and ecologically as good as dead. Consequently, UV-treated discharge can be compliant with the...

Potential contributions of vertically migrating Rhizosolenia to nutrient cycling and new production in the open ocean

We present a numerical model of nutrient uptake and photosynthesis during migrations of the marine diatom Rhizosolenia that was developed to estimate fluxes of carbon and nitrogen due to these migrations in the open ocean. The predicted specific rate of increase of Rhizosolenia was 0.11–0.15 day1, whereas the total time for one migration cycle ranged between 3 and 5 days. Using...

Two Theorems for Time-Dependent Dynamical Systems

James L. REID 0 John J. CULLEN 0 0 Department of Physics and Astronomy, The University of Georgia Athens , Georgia 30602 (Received April 12, 1982) We prove two theorems for certain classes of second