Archimedes' hidden treasure
In 1907, Johan Ludvig Heiberg came upon a many centuries-old book
in a Constantinople library that contained Greek Orthodox prayers
and rites. The book was significant in itself, but on closer
inspection using a magnifying glass, Heiberg realized an even
greater treasure was hidden below the surface text. What he had
discovered were seven treatises by Archimedes in the original
Greek, among which is the only known copy of the illustrious
mathematician's "Method of Mechanical Theorems."
The treatises were copied in the 10th century
and are the earliest surviving works by Archimedes, who lived in
the third century B.C. The writing was washed and scraped off 200
years later by a scribe who reused the pages for a prayer book,
creating a twice-used parchment book known as a palimpsest. The
later script, also in Greek, ran at a 90-degree angle to the
original text, which in places is still discernible to the naked
Tracking a microscopic 'rocket' by its
Using a laser device that allows them to view microscopic
movement, biomedical engineering researchers at Johns Hopkins
have produced startling new findings about how deadly bacteria
spread infection between neighboring cells. Writing in the
October 26 issue of Nature, Scot C. Kuo and James L.
McGrath describe how Listeria monocytogenes--a common source of
poisoning in processed foods--exhibit an unusual stutter-step
motion while building rocketlike "tails" that propel them from
one living host cell to another. The engineers' discovery
contradicts a widely held belief that filaments in these tails
grow and push in a smooth continuous motion.
To study the rocketlike motion of Listeria, the
researchers used an innovative tracking device developed by Kuo.
The instrument--a laser built into an optical microscope--allowed
them to peer inside living cells and record the motion of
Listeria microbes, the potentially fatal pathogens that have
triggered a number of major processed food recalls in recent
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