Retraction of: Scientific Reports https://doi.org/10.1038/srep18210, published online 15 December 2015

The Editors have retracted this Article because significant portions of the text and equations were taken from Roland Molontay’s BSc thesis without attribution1.

The following parts of the paper are copied verbatim or are adapted from those appearing in the thesis: the definition of dB and preceding and subsequent sentences; Definition 3.2; Proof of Lemma 3.4; Lemma 3.5; Proof of Lemma 3.5; Lemma 3.6; Proof of Lemma 3.6; Equation 6; Lemma 3.7; Proof of Lemma 3.7; Lemma 3.8; Equation 8; Proof of Theorem 3.3.

The authors do not agree to the retraction of the Article.