1,062 research outputs found
Coupled Reversible and Irreversible Bistable Switches Underlying TGF-\beta-induced Epithelial to Mesenchymal Transition
Epithelial to mesenchymal transition (EMT) plays important roles in embryonic
development, tissue regeneration and cancer metastasis. While several feedback
loops have been shown to regulate EMT, it remains elusive how they coordinately
modulate EMT response to TGF-\beta treatment. We construct a mathematical model
for the core regulatory network controlling TGF-\beta-induced EMT. Through
deterministic analyses and stochastic simulations, we show that EMT is a
sequential two-step program that an epithelial cell first transits to partial
EMT then to the mesenchymal state, depending on the strength and duration of
TGF-\beta stimulation. Mechanistically the system is governed by coupled
reversible and irreversible bistable switches. The SNAIL1/miR-34 double
negative feedback loop is responsible for the reversible switch and regulates
the initiation of EMT, while the ZEB/miR-200 feedback loop is accountable for
the irreversible switch and controls the establishment of the mesenchymal
state. Furthermore, an autocrine TGF-\beta/miR-200 feedback loop makes the
second switch irreversible, modulating the maintenance of EMT. Such coupled
bistable switches are robust to parameter variation and molecular noise. We
provide a mechanistic explanation on multiple experimental observations. The
model makes several explicit predictions on hysteretic dynamic behaviors,
system response to pulsed stimulation and various perturbations, which can be
straightforwardly tested.Comment: 32 pages, 8 figures, accepted by Biophysical Journa
An SMDP-based Resource Management Scheme for Distributed Cloud Systems
In this paper, the resource management problem in geographically distributed
cloud systems is considered. The Follow Me Cloud concept which enables service
migration across federated data centers (DCs) is adopted. Therefore, there are
two types of service requests to the DC, i.e., new requests (NRs) initiated in
the local service area and migration requests (MRs) generated when mobile users
move across service areas. A novel resource management scheme is proposed to
help the resource manager decide whether to accept the service requests (NRs or
MRs) or not and determine how much resources should be allocated to each
service (if accepted). The optimization objective is to maximize the average
system reward and keep the rejection probability of service requests under a
certain threshold. Numerical results indicate that the proposed scheme can
significantly improve the overall system utility as well as the user experience
compared with other resource management schemes.Comment: 5 pages, 5 figures, conferenc
Photoactive Graphene — From Functionalization to Applications
Photoactive graphene fabricated by chemical functionalization of pristine graphene with different light-harvesting molecules has become one of the most exciting topics of graphene research in the last few years, which remarkably sustains and expands the graphene boom due to its great potentials in various applications. This chapter presents some important issues of photoactive graphene, covering material synthesis, electron/energy- transfer interaction, organic photovoltaic and photocatalystic applications. Of particular interest is the utilization of graphene as a two- dimensional platform to anchor organic conjugated aromatic molecules and their applications in photo-energy conversion and photocatalysis. Challenges currently faced by researchers and future perspectives in this field are also discussed
On the uniqueness of the non-minimal matter coupling in massive gravity and bigravity
In de Rham-Gabadadze-Tolley (dRGT) massive gravity and bigravity, a
non-minimal matter coupling involving both metrics generically re-introduces
the Boulware--Deser (BD) ghost. A non-minimal matter coupling via a simple, yet
specific composite metric has been proposed, which eliminates the BD ghost
below the strong coupling scale. Working explicitly in the metric formulation
and for arbitrary spacetime dimensions, we show that this composite metric is
the unique consistent non-minimal matter coupling below the strong coupling
scale, which emerges out of two diagnostics, namely, absence of Ostrogradski
ghosts in the decoupling limit and absence of the BD ghost from matter quantum
loop corrections.Comment: v2: references added, matches accepted version in Physics Letters B
v1: 6 pages, two-colum
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