The MRI scanner measures this signal difference and displays the activity as a colored area (Figure 1). Diffusion Tensor Imaging (DTI) is a technique that detects how water travels along the white matter tracts in the brain (Figure 2). White-matter tracts connect different parts of the brain and must be protected during surgery. A dye (contrast agent) may be injected into your blood stream.
Dock spiders can swim. A dock spider can actually swim under water and stay submerged for several minutes. It uses air bubbles trapped in the fine hairs on its body under its belly to provide oxygen while it is under water â a bit like a dock spider scuba dive. Dock spiders walk on water.
Many swimming pool owners in Australia find funnel-web spiders in their pools at some point. These spiders cannot jump or live in the bottom of a pool for very long, but they can be deadly to people. Chlorine in the pool water eventually kills them after several hours of swimming around underwater. Air bubbles stick to their leg hairs, which helps them breathe for awhile.