Trade journals target which audience category?

What is the coefficient of AX3 when the following theoretical equation is correctly balanced below? 

Why is ultrasound gel necessary?

Which of the following will result in an increase in propagation velocity?

What will the interference pattern demonstrated in the image below most likely cause?

Calculate the angle of reflection at the boundary between medium 1 and medium 2 if the angle of the incident sound beam is 30º.       Medium      1             2          3            4

Calculate the % transmission at a boundary where the impedance of medium 1 is 2 Rayls and the impedance of medium 2 is 8 Rayls.

A sonographer is scanning and decides that the image is over penetrated.  She turns down the transmit voltage by a factor of 1000.  Calculate the decibel change for this imaging situation.

What process occurs as the ultrasound beam passes through all media, and what are the units of this process?

Using the diagram below, where the x-axis is time; The frequency of waveform 1 is ____________ the frequency of waveform 2 assuming the propagation velocity was the same.