JOHN TIERNEY: “If the United States really has a critical shortage of scientists and engineers, why didn’t this year’s graduates get showered with lucrative job offers and signing bonuses? . . . The only ‘shortage’ is of American-born scientists and engineers. But with so many talented foreigners competing for positions here in schools and laboratories, it’s entirely rational for American students to head into fields where their skills are in more demand — and harder to replace with foreign labor.”