Trains on this day in the past:

[Green_Elite_Cab]

March 12, 2012, SEPTA's 13th Street subway surface trolley station in center city Philadelphia. This is the "inner most" station, on the end of a loop. The trolleys all funnel into this station and then branch outwards towards the different routes.

It was actually hard to get a good shot on this day, for whatever reason. This was for a trip to University of Pennsylvania to see their Flow Cytometery machines. Cell samples are treated with special flourescent dyes, and the cells are rapidly flowed one at a time past a laser, which can determine the size, shape of every individual cell, as well as detect varying levels of the dyes that attach to specific features of the cells. This allows the machine to accurately characterize every cell in a sample, rather than forcing someone to make a guess from a few cells visible in a microscope slide. A fun trip over all, and a great excuse to ride the trolleys!