A method and object-oriented computing system in which a Java implementation of a service is provided dynamically at runtime via a Java interface for the service in accordance with the needs of a client computer in one of two varieties: an Enterprise Java Beans implementation or, alternatively, a non-EJB implementation. The pair of ECG electrodes is disposed at a sharp angle with the mean heart vector, in particular so as to form an angle \u03b2 of about 45\xb0\xb125\xb0 with the projection S of the patient’s spine on the back plate. Where a Z axis is taken in parallel to a normal line direction to the optical sheet and an X axis is taken in a direction of the row of the cylindrical lens elements, a cross sectional shape of the cylindrical lens elements satisfiesZ=X2}X2))+AX4+BX5+CX6+.