Hit by massive funding cuts and a crackdown on student protesters, Columbia University is under fire from US President Donald Trump, putting the world of higher education on tenterhooks. The arrest of student activist Mahmoud Khalil has crystallized concerns over freedom of speech under the Republican leader's administration -- and fueled warnings that Trump is out to quell dissent. Khalil, a US permanent resident with Palestinian roots, recently earned a graduate degree from the prestigious Ivy League school in New York. But he was detained in early March by plainclothes immigration agents over his role in the student movement protesting...