A federal appeals court on Thursday allowed President Trump to continue collecting tariffs under an emergency powers law for ...

Above: A Von Karman vortex street downwind of the Canary Island chain in the eastern Atlantic Ocean off the coast of Africa on Feb. 27, 2015. Image credit: NASA Worldview. Editor's note ...

Abstract: This article presents an efficient synthesis method for generating vortex beams based on donut-shaped orbital angular momentum (OAM) metasurfaces. It not only allows one to synthesize the ...