Abstract: Provided are a lipid and a composition that can effectively deliver an introduction compound such as a nucleic acid to a target cell, tissue, or the like in vivo.

Abstract: A hydraulic control method which includes a step of changing the time rate of introduction per a predetermined unit time of pressurized oil into an oil passage connected to a hydraulically-operated load device, such as a clutch of an automatic transmission, from a first time rate to a second time rate, thereby changing the time-based average oil pressure inside the oil passage from a first oil pressure value to a second oil pressure value. The time rate of introduction of the pressurized oil into the oil passage is changed from the first time rate to the second time rate via a third pressurized oil introduction time rate corresponding to a third oil pressure value different from the first and second oil pressure values. If the second oil pressure value is greater than the first oil pressure value, the third pressurized oil introduction time rate is substantially 100%. If the second pressure value is smaller than the first, the third time rate is substantially 0%.

Abstract: An operation control method for a frictional engagement element which includes engaging means and piston means for urging the engaging means to engage, the operation of the piston means being controlled by means of pressurized oil supplied through a hydraulic control device for producing an oil pressure of the level corresponding to the quantity of electricity supplied thereto. The relationship between the quantity of electricity supplied to the hydraulic control device and the stroke speed of the piston means is previously stored. An ineffective stroke amount of the piston means is detected from the sum total of the products of drive periods, based on the quantities of electricity supplied to the hydraulic control device while the piston means travels through an ineffective stroke section, and stroke speeds corresponding individually to the quantities of electricity. The stored value of the ineffective stroke amount of the piston means is updated to store the detected ineffective stroke amount.