Upon Wnt/β-catenin signaling activation, WRE-bound TCF/β-catenin recruits many co-activator complexes to Wnt target genes. For simplicity only a few representative complexes are illustrated. Dotted lines represent their interactions with β-catenin or between complexes. During active Wnt target gene transcription, APC promotes the exchange between β-catenin/co-activators with co-repressors CtBP, TLE and HDAC in a cyclic manner (double-headed red arrow) while TCF remains bound to the WRE. Ac and Me symbolize histone modifications, such as acetylation and methylation.
Delayed egress is permitted to be installed in buildings with low or ordinary contents. The building is required to be completely sprinkler protected for early control of a fire or protected throughout by a fire-detection system to provide early warning of a fire. The door must also unlock upon loss of power to the locking mechanism and upon fire alarm/sprinkler activation.
An audible sound is required at the door when the release device is operated, which reassures building occupants that the system is functioning and alerts personnel that someone is about to pass through the door and, therefore, allows for time to investigate who is trying to use the door. The door may only be relocked manually after being unlocked via the manual-release device.
The door must unlock upon loss of power to the locking mechanism or the motion sensor. The door must also unlock upon fire alarm and sprinkler activation and remain unlocked until the system is manually reset. Sprinkler protection is not required; however, if provided, sprinkler activation must unlock the doors. The LSC does not require fire-alarm activation via a fire-alarm manual pull station to unlock the door, which provides for a more secure arrangement.
The use of this locking arrangement is limited to doors required for egress from one side only as the egress side of the door must be provided with features to open the door. The locking arrangement is also rendered ineffective each time a person is close enough to activate the motion sensor that unlocks the door. However, the field of view of the motion sensor can be adjusted to reduce unwanted unlocking. It may be desirable to provide a second manual-release device more than 5 feet from the door in areas where patients are transported regularly. This allows the door to be open by the time the patient reaches the door.
Other such reliable means to unlock a door are often accomplished via a coded keypad or a badge reader. It is important to discuss the unlocking approach with an AHJ to ensure that a keypad or badge reader is considered a reliable means to unlock the door.
Complete smoke detection is required throughout the locked space or a remote unlock button must be provided at a constantly attended location within the locked space. Most facilities choose to provide the remote unlock button due to the cost advantages and it has the added benefit of being one of the three allowable methods to unlock the door, which are the same as those detailed for clinical needs. The door must unlock upon loss of power to the locking mechanism. The door must also unlock upon sprinkler activation or area smoke detection provided throughout the locked space if provided in lieu of the remote unlock button. 2b1af7f3a8