An indwelling catheter has a hollow catheter body, a catheter tube fitted to a front end of the catheter body, an elastic valve fitted inside the catheter body, and a hollow plug slidably fitted inside the catheter body. If data is discarded by the transmitter, the transmitter needs to notify the receiver of the discard. request primitive indicating an active scanning for a target Access Point, receiving a frame including a channel congestion indicator from an AP during the probedelay, generating a MLME-SCAN. A central portion of the tube is operatively engaged by the peristaltic pump head so that consecutive portions of the flexible tubing are successively collapsed to thereby propel fluid through the tubing so as to exit the second end. A space or gap is provided between the peaks of the prismatic projections and the seal layer. After forming the gate oxide layer, polysilicon is deposited onto the gate oxide.