A-V Valves Open; Semilunar Valves Closed. This is the first phase of the cardiac cycle. It is initiated by the P wave of the electrocardiogram (ECG), which represents electrical depolarization of the atria. Atrial depolarization initiates contraction of the atrial musculature.
Community Q&A. You can calculate age on Excel for a many applications by combining an undocumented function and the date format for cells. Microsoft Excel internally stores dates as serial numbers, which is the number of days a date is from Jan. 1, 1900.
To calculate the age, the DATEDIF function, set to check year, determines the number of years between the date in the DOB cell and the current date. 1  1. Open the spreadsheet that contains the DOB information you want to convert. 2  2. Insert a blank column next to the column that contains the DOB data, if needed.