A. Nittke et al., THERMODYNAMIC PROPERTIES OF VYCOR AT LOW-TEMPERATURES - EVIDENCE FOR AN ENHANCED CONTRIBUTION OF TUNNELING SYSTEMS, Physical review. B, Condensed matter, 58(9), 1998, pp. 5374-5377
We have measured the heat release and specific heat of Vycor glass at
T<1 K. For a charging temperature of 1 K the heat release shows a lit
time dependence and is approximately ten times larger than for bulk a-
SiO2, in agreement with the specific heat. This result indicates an en
hanced density of states of tunneling systems. Our findings cast some
doubts on the current interpretation of the enhancement of the thermod
ynamic properties of aerogels in terms of fractals.