A discrete, universal denoising method is applied to a noisy signal for which the source alphabet is typically large. The needle assembly includes a housing having a flash chamber, and having a distal end and a proximal end engageable with a specimen collection container. The device can be used for plyometric exercises, specifically push-ups, but it also can be used to perform a variety of different exercises. Since easy assembly, setup, removal, maintenance, re-use, adjustment in display size, excellent display sizeweight ratio and both single-sided and double-sided display can be achieved, the display apparatus is suitable for use in temporary display sites. Air compressor is driven at a high control frequency and a hollow, flexible silicon tube is used as air piping to reduce pulsation of air.