What is 10 dB environmental noise in superconductor measurements?

[jumpjack]

Help with Very High Temperature superconductors (28°C!)

Since several months researchers on www.superconductors.org have published results about Very High Temperature SuperConductors (VHTSC).

A new result has been recently published:
http://www.superconductors.org/28c_rtsc.htm

I don't understand what they mean by "10 dB environmental noise", can anybody explain?
Are their results reliable?

 

[0xDEADBEEF]

The results are complete and utter junk. Resistivity is a poor indicator of superconductivity unless it really drops to zero. The positioning of their 4 point contacts on the picture is very poor, and if they want to show anything, magnetization measurements would be the way to do it. What they show could be due to something mechanical that changes for example, or really a phase transition of a very different kind.
Furthermore, if they do have a sizeable volume fraction of a room temperature superconductor, they could grind their crystal into a powder poor it over a magnet and see little particles hovering in the air.