Caching techniques for use in a computer system comprising a core and at least one edge device. A tubular mediator layer is arranged between the layers to provide an adhesive anchorage for the layers. The conducting medium is also in contact with an interface element that may conform to the contour of a target body surface of the patient when the interface element is applied to that surface. Clasp portions are defined along the arcuate extending edges of the side panels and receivingly engage opposite extending side edges of the back panel insertingly received between inwardly facing surfaces of the clasp portions. A tumble control valve is operated to strengthen the tumble in a combustion chamber to achieve stratified charge combustion with the aid of tumble in an engine operating region higher in engine speed andor engine load.