A data transmission method and protocol includes progressive coding of a data set into time stamped data packets. Aspartic acid derivatives are useful for preparing caspase inhibitors andor prodrugs thereof. The top level of the hash hierarchy, having the hashes of the largest blocks of the master, may be transmitted on a first communication channel, possibly a one-way or broadcast communication channel. This arrangement permits a portion or all of the fluid from one end of the actuator to be regenerated to the other end of the actuator. Accordingly, one can begin to output bits of the second-smallest number even before that final determination. Other embodiments may be described and claimed.