Abstract: A respirator exhalation unit (10) comprises a negative pressure valve (120) and a selectively actuable positive pressure valve assembly (130). The position of the positive pressure valve assembly (130) is selectively adjustable to convert the exhalation unit (10) for use in multiple operating modes, such as a negative pressure mode, a powered air mode, and a self-contained breathing apparatus mode (SCBA). Additionally, a closed circuit breathing apparatus (CCBA) adapter assembly (200) can be attached to the exhalation unit for conversion to a CCBA operating mode. Further, the negative pressure valve (120) divides the interior of the exhalation unit into two chambers, one of which functions as a dead space that protects the user from exposure to any harmful contaminants at the end of exhalation.

Abstract: A respirator exhalation unit (10) comprises a negative pressure valve (120) and a selectively actuable positive pressure valve assembly (130). The position of the positive pressure valve assembly (130) is selectively adjustable to convert the exhalation unit (10) for use in multiple operating modes, such as a negative pressure mode, a powered air mode, and a self-contained breathing apparatus mode (SCBA). Additionally, a closed circuit breathing apparatus (CCBA) adapter assembly (200) can be attached to the exhalation unit for conversion to a CCBA operating mode. Further, the negative pressure valve (120) divides the interior of the exhalation unit into two chambers, one of which functions as a dead space that protects the user from exposure to any harmful contaminants at the end of exhalation.

Abstract: An improved matching system for trading instruments in which the occurrence of automatically confirmed trades is dependent on receipt of match acknowledgement messages by the host computer (200) from all counterparties (KS A, KS B) to the matching trade. The host computer (200) matches like bids and offers provided thereto by the various keystations (KS A, KS B) in accordance with a predetermined matching criteria. Each of the keystations (KS A, KS B) includes a trade status timer (300, 302) and a display (310, 312) for timing receipt of a confirmed trade and/or ticket generation message from the host (200) after the keystation (KS A, KS B) has sent a match acknowledgement message and for displaying an “unconfirmed trade” status message awaiting receipt of the “confirmed trade” indication from the host (200). An alarm and a display message is provided at the keystation (KS A, KS B) when the “confirmed trade” indication is not timely received.

Abstract: An improved matching system for trading instruments in which the occurrence of automatically confirmed trades is dependent on receipt of match acknowledgement messages by the host computer (200) from all counterparties (KS A, KS B) to the matching trade. The host computer (200) matches like bids and offers provided thereto by the various keystations (KS A, KS B) in accordance with a predetermined matching criteria. Each of the keystations (KS A, KS B) includes a trade status timer (300, 302) and a display (310, 312) for timing receipt of a confirmed trade and/or ticket generation message from the host (200) after the keystation (KS A, KS B) has sent a match acknowledgement message and for displaying an "unconfirmed trade" status message awaiting receipt of the "confirmed trade" indication from the host (200). An alarm and a display message is provided at the keystation (KS A, KS B) when the "confirmed trade" indication is not timely received.

Abstract: A video conversational data communication network (30) in which subscribers (34, 36) may conduct conversational video textual data communications with one or more keystations (70, 602, 98) in the network (30). Each keystation (70, 602, 98) is associated with a keystation terminal controller interface (68, 96, 600) which is in turn connected to a message switching node (32) for routing calls throughout the network (30). The keystation controller interface (68, 96, 600) locally stores (304, 306) video conversational textual data for its associated keystations (70, 82, 84, 98, 100, 602) and enables two different designated keystations to conduct two different video conversations with a common keystation in a split screen display (76). The split screen display (76) may also be used to display retrievable data from a data base (50, 52) for simultaneous display (76) along with a video conversation.

Abstract: A video conversational data communication network (30) in which subscribers (34, 35) may conduct conversational video textual data communications with one or more keystations (70, 602, 98) the network (30). Each keystation (70, 602, 98) is associated with a keystation terminal controller interface (68, 96, 600) which is in turn connected to a message switching node (32) for routing calls throughout the network (30). The keystation controller interface (68, 96, 600) locally stores (304, 306) video conversational textual data for its associated keystations (70, 82, 84, 98, 100, 602) and enables two different designated keystations to conduct two different video conversations with a common keystation in a split screen display (76). The split screen display (76) may also be used to display retrievable data from a data base (50, 52) for simultaneous display (76) along with a video conversation.