The researchers did not try to identify the causes of the increase, but they have some theories.

VOA: special.2009.08.06

Joule actually did this experiment, and he observed that for the gas expansions that he could do, that the temperature did not increase measurably.

事实上焦耳的确做了这个实验，他做到了,他能达到的最好实验要求，发现在可测量范围内没有观察到温度上升。

麻省理工公开课 - 热力学与动力学课程节选

"We did not anticipate that there would be an increase in this group and we believe it may be an indicator of a new risk factor for gastric cancer which has not yet been identified."

VOA: standard.2010.05.12