An electrosurgical system and method for performing electrosurgery is disclosed. The actual time of arrival of data at the inputs to a memory device is determined by sending back-to-back write commands along with a predetermined data pattern to the memory device. More particularly, the improved techniques obtain improved propagation of data messages to and from synchronization queues which back up main queues associated with the software modules. Raw images are calculated from measuring data from a partial contour interval, the planes of the images thereof being inclined in relation to a central plane containing the focal path, and a plurality of raw images are collected to form a CT image. A distillation vapor stream is withdrawn from the column below the feed point of the first stream and compressed to an intermediate pressure, and is then directed into heat exchange relation with the tower overhead vapor stream to cool the distillation stream and condense substantially all of it, forming a condensed stream.