Assad has overseen the most directed, widespread killing of civilians by state forces since the Sudanese President Omar al-Bashir's militias rampaged through Darfur a decade ago.
From 1950 to 1970, at least 252 crew members crashed on spy flights of all kinds, most directed against the Soviet Union, Mr. Taubman reports.
For more than three years, Hamas has been shooting crude rockets from northern Gaza, with most directed at the Israeli town of Sederot, just outside Gaza.
"Let's make sure that what we're cutting is really excess weight," Mr. Obama said, in what may be the line in his hourlong speech that was most directed at the Tea Party caucus.
And, making matters even more complicated, Netanyahu is shadowed by his would-be successor, Yair Lapid, a centrist secularist and cabinet minister whose passions seem most directed at a confrontation with the ultra-Orthodox rather than a peace with the Palestinians.
To date, most directed evolution studies have used either Escherichia coli or Saccharomyces cerevisiae as a host; however, other bacterial and yeast species, as well as mammalian and insect cell lines, have also been successfully used.
