The lack of a dimensional osmosis damper on the Tryst's Continuous Event Transmuter meant that the display was able to be entered by anyone that viewed it. (TV: Nightmare of Eden) The Tenth Doctor later mentioned the piece of technology. (PROSE: Martha in the Mirror)
When the Third Doctor was drawn to a time period shortly after the Tenth Doctor had regenerated, the Tenth Doctor unknowingly drew on the energy of his past self to stabilise his own regeneration simply because the two Doctors were in close proximity to each other without either Doctor coming face-to-face. The Third Doctor described the experience as "energy osmosis" as the weaker incarnation took energy from the stronger, although he simply felt a brief fatigue and was then back to normal while the Tenth was fully restored. (PROSE: The Christmas Inversion)
Behind the scenes Edit
Although not elaborated on fully in-universe, osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.