The present invention provides a method for approximating the flow rate of hydraulic fluid in an automatic transmission. A lower limit value to a lower limit value setting circuit of the DC-DC converter is switched to a first lower limit value, if the mode signal prescribes the active mode, on the other hand, the lower limit is switched to a second lower limit value, which is higher than the first lower limit value, if the mode signal prescribes an inactive mode. In certain embodiments, the system is capable of causing scar tissue to form in ostial areas of the atrium rather than inside the pulmonary vein. NRP cells self renew over multiple passages in the presence of fibroblast growth factor and neurotrophin 3 and express a characteristic subset of neuronal epitopes.