45,500 research outputs found
From Electric Circuits to Chemical Networks
Electric circuits manipulate electric charge and magnetic flux via a small
set of discrete components to implement useful functionality over continuous
time-varying signals represented by currents and voltages. Much of the same
functionality is useful to biological organisms, where it is implemented by a
completely different set of discrete components (typically proteins) and signal
representations (typically via concentrations). We describe how to take a
linear electric circuit and systematically convert it to a chemical reaction
network of the same functionality, as a dynamical system. Both the structure
and the components of the electric circuit are dissolved in the process, but
the resulting chemical network is intelligible. This approach provides access
to a large library of well-studied devices, from analog electronics, whose
chemical network realization can be compared to natural biochemical networks,
or used to engineer synthetic biochemical networks
Revealing networks from dynamics: an introduction
What can we learn from the collective dynamics of a complex network about its
interaction topology? Taking the perspective from nonlinear dynamics, we
briefly review recent progress on how to infer structural connectivity (direct
interactions) from accessing the dynamics of the units. Potential applications
range from interaction networks in physics, to chemical and metabolic
reactions, protein and gene regulatory networks as well as neural circuits in
biology and electric power grids or wireless sensor networks in engineering.
Moreover, we briefly mention some standard ways of inferring effective or
functional connectivity.Comment: Topical review, 48 pages, 7 figure
Routing Physarum with electrical flow/current
Plasmodium stage of Physarum polycephalum behaves as a distributed dynamical
pattern formation mechanism who's foraging and migration is influenced by local
stimuli from a wide range of attractants and repellents. Complex protoplasmic
tube network structures are formed as a result, which serve as efficient
`circuits' by which nutrients are distributed to all parts of the organism. We
investigate whether this `bottom-up' circuit routing method may be harnessed in
a controllable manner as a possible alternative to conventional template-based
circuit design. We interfaced the plasmodium of Physarum polycephalum to the
planar surface of the spatially represented computing device, (Mills' Extended
Analog Computer, or EAC), implemented as a sheet of analog computing material
whose behaviour is input and read by a regular 5x5 array of electrodes. We
presented a pattern of current distribution to the array and found that we were
able to select the directional migration of the plasmodium growth front by
exploiting plasmodium electro-taxis towards current sinks. We utilised this
directional guidance phenomenon to route the plasmodium across its habitat and
were able to guide the migration around obstacles represented by repellent
current sources. We replicated these findings in a collective particle model of
Physarum polycephalum which suggests further methods to orient, route, confine
and release the plasmodium using spatial patterns of current sources and sinks.
These findings demonstrate proof of concept in the low-level dynamical routing
for biologically implemented circuit design
Gradient and Passive Circuit Structure in a Class of Non-linear Dynamics on a Graph
We consider a class of non-linear dynamics on a graph that contains and
generalizes various models from network systems and control and study
convergence to uniform agreement states using gradient methods. In particular,
under the assumption of detailed balance, we provide a method to formulate the
governing ODE system in gradient descent form of sum-separable energy
functions, which thus represent a class of Lyapunov functions; this class
coincides with Csisz\'{a}r's information divergences. Our approach bases on a
transformation of the original problem to a mass-preserving transport problem
and it reflects a little-noticed general structure result for passive network
synthesis obtained by B.D.O. Anderson and P.J. Moylan in 1975. The proposed
gradient formulation extends known gradient results in dynamical systems
obtained recently by M. Erbar and J. Maas in the context of porous medium
equations. Furthermore, we exhibit a novel relationship between inhomogeneous
Markov chains and passive non-linear circuits through gradient systems, and
show that passivity of resistor elements is equivalent to strict convexity of
sum-separable stored energy. Eventually, we discuss our results at the
intersection of Markov chains and network systems under sinusoidal coupling
Circuit Synthesis of Electrochemical Supercapacitor Models
This paper is concerned with the synthesis of RC electrical circuits from
physics-based supercapacitor models describing conservation and diffusion
relationships. The proposed synthesis procedure uses model discretisation,
linearisation, balanced model order reduction and passive network synthesis to
form the circuits. Circuits with different topologies are synthesized from
several physical models. This work will give greater understanding to the
physical interpretation of electrical circuits and will enable the development
of more generalised circuits, since the synthesized impedance functions are
generated by considering the physics, not from experimental fitting which may
ignore certain dynamics
Roadmap on semiconductor-cell biointerfaces.
This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world
A Novel Method of Solving Linear Programs with an Analog Circuit
We present the design of an analog circuit which solves linear programming
(LP) problems. In particular, the steady-state circuit voltages are the
components of the LP optimal solution. The paper shows how to construct the
circuit and provides a proof of equivalence between the circuit and the LP
problem. The proposed method is used to implement a LP-based Model Predictive
Controller by using an analog circuit. Simulative and experimental results show
the effectiveness of the proposed approach.Comment: 8 page
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