The present invention solves the problem that the color temperature of initial setting is changed, when a PDP is driven for a long period of time, due to the non-uniform deterioration of red, green and blue fluorescent materials that is caused by the ultraviolet rays generated for discharge. The upper and lower members are actuated by a horizontal fastening device which can be tightened or loosened with one hand. The valve assembly controls the magnitude of the hydraulic pressure conveyed to the working cylinder and determines the direction of effect of the working cylinder. It is difficult for the subscriber to keep the greeting brief yet informative. Accordingly, methods and apparatus herein advantageously require less computational complexity andor memory usage than that needed if estimating the required back-off based on similar metrics obtained for the multi-carrier signal as a whole. In particular aspects, the system allows monitoring of such dynamic processes continually and to focally manipulate the cells by focal application of growth factors such as BMP, CNTF and other growth factors.