Acoustic microscopy acoustic microscope (CSAM), and C-mode scanning acoustic microscope (C-SAM). More recently acoustic microscopes based around picosecond ultrasonics systems have demonstrated acoustic imaging in cells using sub-optical wavelengths working with ultrasonic frequencies into the multi-GHz. Since the vast majority of acoustic microscopes in use today are C-SAM type instruments, this discussion will be limited to these instruments. Ultrasound is broadly defined as any sound having a frequency above 20 kHz, which is approximately the highest frequency that can be detected by the human ear. However, the acoustic microscopes emit ultrasound ranging from 5 MHz to beyond 400 MHz so that micrometre
What Is History? and were instead products of their own places and times, which in turn decided what "facts of the past" they determined into "facts of history". British historian Richard J. Evans said "What Is History?" caused a revolution in British historiography in the 1960s. Australian historian Keith Windschuttle, a critic of Carr, said "What Is History?" is one of the most influential books written about historiography, and that very few historians working in the English language since the 1960s had not read it. What Is History? What Is History? is a study that was written by the English historian E. H.