 Commercial products, therapeutic claims and services supposedly based on his work appear at present to be best regarded as such.But in the later 20th century, Gurwitsch's daughter Anna, along with Colli, Quickenden and Inaba, separately returned to the subject, referring to the phenomenon more neutrally as "dark luminescence", "low level luminescence", "ultraweak bioluminescence", or "ultraweak chemiluminescence".Their common basic hypothesis was that the phenomenon was induced from rare oxidation processes and radical reactions.