the previous tests there were not enough and (the only two nickel isotopes which can fuse with hydrogen), at 3.6% and 0.9% respectively, in the reactants to explain the 10% copper output; these isotope levels are typical of natural copper, rather than of fusion by-product. According to Siegel, Rossi also refused to unplug the machine while it was operating despite it being an easy way to surreptitiously power the device. He also added that the supposedly independent testers had to rely on data supplied by Rossi. In October 2014 a non-peer-reviewed paper by the same authors as the May 2013 report describes results from evaluations in March 2014 of an upgraded version of the E-Cat which runs at higher temperatures. Unlike previous demonstrations, the test was carried out with monitoring equipment and in a laboratory not supplied by Rossi, and was run over an extended duration (32 days). However, as with the previous report, the authors were not in full control of the process; Rossi intervened during the insertion of the fuel charge, start up of the reactor, shut down of the reactor, and extraction of the spent fuel. Overall, the total excess heat measured was calculated to be well beyond that possible by any conventional, non-nuclear source. In this report, they present analyses of samples of spent fuel, concluding from the isotopes found that "nuclear reactions are therefore indicated to be present in the run process, which however is hard to reconcile with the fact that no radioactivity was detected outside the reactor during the run." Following fuel and ash isotopic analysis, the authors speculate as to isotopes of especially nickel and lithium being part of the reaction, in particular transmutation of and to , and from to through some unknown process. Particle physicist Tommaso Dorigo commented on the 2014 test, called the isotopic measurements "startling" but he expressed deep concern about Rossi being involved in collecting the spent fuel, that the testers may have "overlooked some simple trick" and that "given the extraordinary nature of the claim… this constitutes a major flaw, which totally invalidates any conclusions one might otherwise draw." Astrophysicist Ethan Siegel was highly critical of the test, stating that the testers were not independent, that Rossi could have tampered with the fuel samples, that the 'open calorimeter' setup used was inappropriate, and that "it’s relatively easy to fake the amount of energy being drawn through