Bifurcations in a model of monolithic passively mode-locked semiconductor laser

Operation regimes of a two section monolithic quantum dot mode-locked laser are studied theoretically using a model that takes into account carrier exchange between quantum dots and wetting layer. It is shown that when the absorber section length is large enough the laser exhibits bistability between laser off state and different mode-locking regimes. Q-switching instability leading to slow modulation of the mode-locked pulse peak intensity is completely eliminated in this case

TASEP modelling provides a parsimonious explanation for the ability of a single uORF to derepress translation during the integrated stress response

Translation initiation is the rate-limiting step of protein synthesis that is downregulated during the Integrated Stress Response (ISR). Previously, we demonstrated that most human mRNAs that are resistant to this inhibition possess translated upstream open reading frames (uORFs), and that in some cases a single uORF is sufficient for the resistance. Here we developed a computational model of Initiation Complexes Interference with Elongating Ribosomes (ICIER) to gain insight into the mechanism. We explored the relationship between the flux of scanning ribosomes upstream and downstream of a single uORF depending on uORF features. Paradoxically, our analysis predicts that reducing ribosome flux upstream of certain uORFs increases initiation downstream. The model supports the derepression of downstream translation as a general mechanism of uORF-mediated stress resistance. It predicts that stress resistance can be achieved with long slowly decoded uORFs that do not favor translation reinitiation and that start with initiators of low leakiness