Feng, JingchenSevier, Stuart A.Huang, BinJia, DongyaLevine, Herbert2017-05-192017-05-192016Feng, Jingchen, Sevier, Stuart A., Huang, Bin, et al.. "Modeling delayed processes in biological systems." <i>Physical Review E,</i> 94, no. 3 (2016) American Physical Society: https://doi.org/10.1103/PhysRevE.94.032408.https://hdl.handle.net/1911/94293Delayed processes are ubiquitous in biological systems and are often characterized by delay differential equations (DDEs) and their extension to include stochastic effects. DDEs do not explicitly incorporate intermediate states associated with a delayed process but instead use an estimated average delay time. In an effort to examine the validity of this approach, we study systems with significant delays by explicitly incorporating intermediate steps. We show that such explicit models often yield significantly different equilibrium distributions and transition times as compared to DDEs with deterministic delay values. Additionally, different explicit models with qualitatively different dynamics can give rise to the same DDEs revealing important ambiguities. We also show that DDE-based predictions of oscillatory behavior may fail for the corresponding explicit model.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1103/PhysRevE.94.032408