Julia Kagan is a financial/consumer journalist and former senior editor, personal finance, of Investopedia. Khadija Khartit is a strategy, investment, and funding expert, and an educator of fintech ...

Control theory is a branch of mathematics and engineering, which defines the conditions needed for a system to maintain a controlled output in the face of input variation. Classically developed for ...

Photonic crystals are periodic optical structures that can control the flow of light. Multiple reflections from surfaces separated by a distance similar to the wavelength prevent an optical beam from ...