Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Maritime Security on the Asia-Pacific: A Navigational Map for the New U.S. Administration

Created as part of the 2017 Jackson School for International Studies SIS 495: Task Force.Maritime security in the Asia-Pacific entails “traditional” security concerns such as naval power, and “non-traditional” security issues such as piracy, climate change and fisheries depletion. This task force evaluates policy options for a comprehensive maritime strategy for U.S. leadership