years. Reference is also made to the advancement of transporter technology in the same episode, where Chief O'Brien states that each individual transporter pad has four redundant scanners whereby in the event a scanner fails the other three will take over, and that he has never lost anyone having been a transporter operator for over 20 years. In "Rascals", several adult Enterprise crew members were beamed off a shuttle and rematerialized as children still in their adult sized clothing, the incoming "matter stream" had a commensurate drop in mass, the operator had initially thought the reduction in mass meant "we may have lost one". In the Voyager episode "Tuvix", a transporter accident combines both the physical and behavioral aspects of Lt. Tuvok and Neelix into a single being wearing a melange of each other's clothing. Notably, Tuvix was of equal mass of both Tuvok and Neelix combined. When they were later separated, Neelix and Tuvok were both wearing Starfleet uniforms. Technological and scientific restrictions While several characters have asserted that transporters cannot transport through a ship's shields or planetary defense shields, there are instances of this "rule" being broken through a technobabble solution (TNG: "The Wounded", DS9: "Trials and Tribble-ations") or disregarded by the show's writers (Voyager: "Caretaker"). The non-canon TNG Technical Manual describes how a starship may create "windows" in the shield geometry through which a transporter beam may propagate at the expense of creating weak spots in the vessel's defensive field. In Star Trek II: The Wrath of Khan, Vice Admiral James T. Kirk and Lieutenant Saavik carry on a conversation during rematerialization. In Star Trek IV: The Voyage Home, Dr. Gillian Taylor jumps into Kirk's transporter beam during dematerialization, and rematerializes without any apparent ill effects. This is probably due to the "annular confinement beam", a component of the transporter mentioned in the various television episodes which serves to keep patterns separate from one another. In the same film, Mr. Spock is beamed onto a cloaked ship while walking. According to the TNG Technical Manual, the transporter cannot move antimatter, but in the Voyager episode "Dark Frontier" Voyager transported a live photon torpedo equipped with antimatter onto a Borg ship. Also in TOS episode "Obsession" Kirk and a fellow crewman beam down to the surface of a planet with an antimatter bomb. The TAS episode "One of Our Planets Is Missing" has the Enterprise beaming a chunk