Matter in a Warped and Oscillating Background

We examine the role of matter in an oscillating background with a warped, compact extra dimension. This background is compatible with an S^1/Z_2 orbifold structure which allows chiral fermions to be included in the scenario. When the background oscillates rapidly, the leading coupling of these oscillations is to gauge fields rather than fermions. If the decay of these oscillations were to occur today, it could provide an alternative mechanism for generating the ultra high energy cosmic rays.