Sludge may be continuously or intermittently discharged. Both direct and indirect monitoring can be done intermittently or continuously. Many systems pulse LEDs on and off, by applying power periodically or intermittently. Pressure can be applied constantly or intermittently. Giving beta-lactam antibiotics continuously may be better than giving them intermittently. It automatically selects the least jammed frequencies and can transmit intermittently or randomly. However, for a time Eastern electricity continued to be supplied albeit intermittently. Some of the most difficult troubleshooting issues relate to symptoms which occur intermittently. Regular excavations began in 1738, and have continued ever since, albeit intermittently. The district was nearly deserted by 1875, and was worked only intermittently afterward. It would last intermittently until 1887. Barrymore endured a troubled youth and continued to act intermittently during the decade. Those that drain toward the Pacific Ocean are steep and short, flowing only intermittently. A single sawtooth, or an intermittently triggered sawtooth, is called a ramp waveform. During the rest of the year Egypt opened and closed the crossing intermittently.