A method for protecting firewall load balancers from a denial of service attack is provided. A nucleus of compressible elastomeric material is surrounded by a winding of a slender strand of flexible tension-bearing material oriented at a pitch angle relative to a central axis. The FIFO queue implementation includes a central queue and an elimination structure for eliminating enqueue-dequeue operation pairs. If the refresh backlog count value is not less than the predetermined value or the rank of memory devices is not in a powered down state, the Idle Count threshold value is set based on the slope of an Idle Delay Function such that a refresh operation will be performed accordingly. The modules also enable separate generation of first and second order PMD, and can be used in a completely deterministic manner to achieve the desired PMD. The shutter is located at the block position when the operation member is located at the second position.