The focus of this research is on the signal processing techniques needed to develop a new imaging modality to detect the current distribution that exists within the body. This modality is based on the passive measurement of the magnetic fields of the body. The investigators will develop mathematical and physical models to solve the magnetic inverse problem, compute the current distribution, locate the position of the conductors in 3-D free space, and reconstruct the image of the current distributions in a bounded conduction medium. This research is important since it will contribute to an imaging modality that is totally noninvasive and which has the potential to measure physiological events (currents) which cannot be detected by any of the present medical imaging devices. The main application of this imaging modality is expected to be in tracking the electrical activity of the heart and the brain.