Acetaldehyde precursors useful in flavors and fragrances, especially in consumable products, are according to the formula I wherein R1 and R2 are selected such that both are \u2014CH2CH3, or both are linear, branched or cyclic alkyl, aryl, alcohol or sugar residues, and n=1-10, with the proviso that, when R1 and R2 are selected such that both are \u2014CH2CH3, n=1, 2, 3 or 4. Source data of image elements with two or more colors is obtained and displayed so that the user can view an image of the source data while freely adjusting the colors of the logo data according to the colors that can be used by the printer. The engine is operated with a lean air-fuel ratio when a temperature of the HC adsorbing catalyst andor a temperature of the NOx adsorbing catalyst is equal tohigher than the predetermined value. An interceptor portion of the sheet interceptor, which intercepts light from the right-hand side of a range on the screen within which a partial image is projected, can be displaced horizontally relative to an interceptor portion thereof that intercepts light from the left-hand side thereof. In the intermediate layer, there is formed of segregate grains and a boundary phase which surrounds and isolates the grains, The magnetic layer has magnetic grains formed following the structure of the intermediate layer. The tree chipper may comprise a boom that can be moved to position the tree chipper against a tree to be cut and chipped.