Abstract: An instrument sheath that can be inserted into an incision formed in tissue. The sheath may protect the tissue from mechanical, thermal and other forms of trauma. The application also includes a blade guide that can be used to form an incision.

Abstract: Disclosed is an array of seismic energy receiver elements spaced specifically for attenuation of horizontally traveling seismic waves. In one embodiment, the rows of seismic energy receiver elements are spaced apart a crossline distance d and have a total crossline extent D, and d is less than the velocity divided by the maximum frequency of the noise to be attenuated and D is greater than the velocity divided by the minimum frequency of the noise to be attenuated. In another embodiment, two or more arrays of seismic energy receiver elements are interleaved. Also disclosed herein is a method for processiong seismic energy signals to attenuate predetermined wavelengths of seismic waves.