Covert Channel are the methods to conceal a message in the volatile medium carrier such as radio signal and network packets. Until now, covert channels based on the packet length produce abnormal packet length when the length of the message is long. Abnormal packet length, especially in the normal network will expose the covert channels to network security perimeter. Therefore, it motivates the...

conclusions the findings showed that adding sufentanil or midazolam to bupivacaine shortens the onset of spinal anesthesia and increases the time duration of anesthesia; however it does not change the motor block recovery time. adding sufentanil delays the first request for narcotic analgesics while adding midazolam leads to a decrease in nausea and hypotension. adding sufentanil or midazolam d...