Book Review

This essay considers how teaching and learning may have functioned in late antique Roman classrooms by examining two texts: one is from the teacher’s perspective, the other – which, until recently, was unedited – provides some access to the student’s perspective. Despite much recent scholarly work on education in antiquity, there has been no attempt to bring teachers’ and students’ perspectives together through two contemporary sources from the Latin-speaking West. The first text is by Servius, a late antique teacher, whose Commentary provides detailed analysis of Virgil. The other comprises the Colloquia, containing ‘real life’ dialogues in Latin and Greek set in a school context. Through this comparison, the author aims to shed some light on what may have happened in a Latin-speaking classroom in late antiquity.     

Optofluidic characterization of marine algae using a microflow cytometer

The effects of global warming, pollution in river effluents, and changing ocean currents can be studied by characterizing variations in phytoplankton populations. We demonstrate the design and fabrication of a Microflow Cytometer for characterization of phytoplankton. Guided by chevron-shaped grooves on the top and bottom of a microfluidic channel, two symmetric sheath streams wrap around a central sample stream and hydrodynamically focus it in the center of the channel. The lasers are carefully chosen to provide excitation light close to the maximum absorbance wavelengths for the intrinsic fluorophores chlorophyll and phycoerythrin, and the excitation light is coupled to the flow cytometer through the use of an optical fiber. Fluorescence and light scatter are collected using two multimode optical fibers placed at 90-degree angles with respect to the excitation fiber. Light emerging from these collection fibers is directed through optical bandpass filters into photomultiplier tubes. The cytometer measured the optical and side scatter properties of Karenia b., Synechococcus sp., Pseudo-Nitzchia, and Alexandrium. The effect of the sheath-to-sample flow-rate ratio on the light scatter and fluorescence of these marine microorganisms was investigated. Reducing the sample flow rate from 200 μL/min to 10 μL/min produced a more tightly focused sample stream and less heterogeneous signals.