Natural killer cells act as the immune system’s rapid-response team, but the stress of anxiety and insomnia may be quietly thinning their ranks. A study of young women in Saudi Arabia found that both ...

Twenty years after the introduction of the theory, we revisit what it does—and doesn’t—explain. by Clayton M. Christensen, Michael E. Raynor and Rory McDonald Please enjoy this HBR Classic. Clayton M.

President Trump has set his sights on defunding colleges, singling out some of the world’s wealthiest schools in what critics say is an attack on academic freedom. Some are negotiating. Others are ...