A display apparatus includes a display-controlling substrate and an opposite substrate facing the display-controlling substrate. Multiple exercises that exercise various muscle groups of the human body may be performed with the exercise device. The diastolic function test may be repeated periodically with results stored in memory for later downloading to an external device allowing a physician to monitor the diastolic response to a selected treatment. The venting openings are disposed one above the other with no obstructions therebetween in order to allow for direct air transfer between the inside and the outside of the cover while preventing weather elements from entering the cover. A control block determines whether a DC voltage level of the output signal output from the operational amplifier has reached a reference value, and controls a total impedance of the impedance unit based on a result of the determination. In the preferred embodiment, the design utilizes deep tanks, as defined in the specification, to enable the chemicals to be utilized over an extended period of time.