An actual open briefcase contains a pair of sculpted hands pushing up against a sheet of glass.
Two antennas (one vertical, one horizontal) emerge from a wooden box that contains a pair of tone-producing oscillators.
In animal cells each centrosome contains a pair of cylindrical centrioles, which are themselves composed of complex arrays of microtubules.
The ventral medulla contains a pair of triangular structures called pyramids, within which lie the pyramidal tracts.
To measure the heart rate, for instance, the shirt contains a pair of non-sticky sensors that can produce a simplified electrocardiogram.
One gallery, a twenty-three-foot cube, contains a pair of Rothkos and a dark Richard Serra on linen that wraps around a corner; the room at once forces you to focus inward and lifts you up, like Borromini.
The book contains a pair of overhead photographs, part of an experiment conducted by Otis, of elevators loaded to capacity (by design, cabs are nearly impossible to overweight, unless the passengers are extremely tall).
Billed as "the fun way to explain the menstrual cycle to kids", the Period Party pack contains a pair of doll-sized pants, 18 reusable sanitary pad stickers, a calendar, stickers to track Lammily's period and a guide on what happens during the menstrual cycle.
It also contains a pair of musicological essays and dozens of Guthrie's drawings, paintings and handwritten lyrics, drawn from the vast collection bequeathed to the Smithsonian 25 years ago by the estate of Moe Asch, founder of Folkways Records, the label for which Guthrie recorded much of his best work.
More importantly, it also contains a pair of 60 kilowatt (80 horsepower) electric motors.From a standstill, with the engine switched off, an electric motor at the back of the transmission winds the vehicle up to 30mph provided the driver goes gently on the accelerator pedal.
The nanosensor contains a pair of interdigitated electrodes deposited on the nanoporous polymer membranes.
