National security, unlocked. Each Thursday, host Mary Louise Kelly and a team of NPR correspondents discuss the biggest national security news of the week. With decades of reporting from battlefields ...

During femtosecond laser fabrication, photons are mainly absorbed by electrons, and the subsequent energy transfer from electrons to ions is of picosecond order. Hence, lattice motion is negligible ...

This widely used method of calculating returns considers a portfolio's cash flows Will Kenton is an expert on the economy and investing laws and regulations. He previously held senior editorial roles ...