We outline inversion procedures for inverting acoustic data in the geophysics problem of well to well imaging under the assumption that the inhomogeneous medium depends on two variables. We give both the exact inversion procedure and the procedure valid in the Born approximation. We include an inversion procedure for evanescent waves as well as propagating waves.

The welfare of White Leghorn hens housed in conventional (CON) and modifi ed (MOD) battery cages was assessed by evaluating behaviour during the laying period. CON (30x45cm) (n=84) and MOD (60x45cm) (n=84) each provided 450cm2 of fl oor space for 3 hens. MOD included a perch (30x5cm) and a nest box (NB) (24x45cm), providing an additional 360cm2 of nest area per bird. Location of lay was assesse...