A logic chip useful for emulation and prototyping of integrated circuits. The proximal hub assembly can include an interference fit member which forms an interference fit with a carrier tube to reduce the tendency of the device to fall out of the carrier tube during handling and to provide for easy removal of the device when ready for use. The backlight module can output the positive and negative levels of driving voltage from an output end of the inverter to drive LEDs through alternately switching. A calibration map is made on a calculated basis with each pixel or voxel representative of a color hue indicative of wash-out behavior and a color intensity indicative of wash-in behavior. The information may also reveal whether the group provides a service being sought by the joining device or may otherwise influence whether the joining device will attempt to join a group. A curved portion is provided in the exhaust duct, and the filter is provided on a downstream side in a direction of flow of the gas with respect to the curved portion.