Nanotechnology is the understanding and control of matter generally in the 1-100 nm dimension range. The application of nanotechnology to medicine, known as nanomedicine, concerns the use of precisely engineered materials at this length scale to develop novel therapeutic and diagnostic modalities. Nanomaterials have unique physicochemical properties, such as ultra small size, large surface area to mass ratio, and high reactivity, which are different from bulk materials of the same composition. These properties can be used to overcome some of the limitations found in traditional therapeutic and diagnostic agents.

Repeated observation of TCP retransmission timer problems stimulated investigation into the roles and limitations of timers. Timers are indispensable tools in building up reliable distributed systems. However, as the experience with the TCP retransmission timer has shown, timers have intrinsic limitations in offering optimal performance. Any timeout based action is a guess based on incomplete information, and as such is bound to be non-optimal. We conclude that, if we aim at high performance, we should use external events as a first line of defense against failures, and depend on timers only in cases where external notification has failed.