About: http://webisa.webdatacommons.org/6934233

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	As you point out above, ?? is not a constant with r. ?? is the thermal diffusivity = thermal conductivity, k (which is a constant), divided by the product of the density, ??, and the heat capacity at constant pressure, Cp = k/(??Cp).
http://www.w3.org/ns/prov#wasQuotedFrom	wattsupwiththat.com