As President Barack Obama rightly noted in one of his first directives, his "highest priority is to keep the American people safe."[1] Addressing homeland security challenges effectively requires ...

Now, on to the subject of complex numbers. We have stayed away from this subject until now simply because we did not want to confuse things. Initially, it is easy to think of signals as “real valued.” ...

Many important phenomena, concerning ecosystems, societies, our health, or even science itself, are more than the simple sum of their parts. Complex systems are what emerge when basic building blocks ...