Moreover, there exists feedback regulation within the HIF pathway as well as crosstalk and synergism with other pathways, e.g. NFκB and mTOR (Cavadas et al., 2013).
In addition, even if a mechanistic understanding of these processes exists, feedbacks between and within social and ecological systems are often ignored (Nicholson et al. 2009) or prone to inconsistencies (Cumming et al. 2005).
In order to allow feeding input signals to be propagated, even in the case that no feedback signals exist, the feedback signal is biased by a constant unit value.
In the first example, we show that there does exist a feedback operator (Theta (cdot)in L^{infty }_{mathbb {F}}(Omega ;L^{2}(0,T;{R}thbb {R}}^{mtimes n}))) for this case; while in the second one, it is shown that the desired feedback operator may not exist for another situation.
Our experimental data showed that the inhibiting kinase activity of MEK (MAP kinase kinase) on ERK lowered the MEK response with EGF, indicating that there might exist positive feedback by ERK somewhere within upstream pathways.
We also assume that there exists a feedback channel between each legitimate user and the transmitter.
Then Theorem 1 assures that there exists a feedback gain matrix K so that systems (3.11) and (3.12) realize the synchronization.
Then, from Theorem 2, there exists a feedback controller with dimension (operatorname{dim} mathcal{X}_{ K}=operatorname{dim} mathcal{V}_{2}-operatorname{dim} mathcal{V}_{1}=2).
As RGS4 is only transiently up-regulated by Sim1, there likely exists a feedback loop to maintain a proper level of RGS4 and hence the homeostasis of serotonin release.
In addition, no system exists for feedback when patients are transferred between different DM clinics.
