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Bistable systems

A J Alvarez-Socorro, M G Clerc, G González-Cortés, M Wilson
Multistable systems exhibit a rich front dynamics between equilibria. In one-dimensional scalar gradient systems, the spread of the fronts is proportional to the energy difference between equilibria. Fronts spreading proportionally to the energetic difference between equilibria is a characteristic of one-dimensional scalar gradient systems. Based on a simple nonvariational bistable model, we show analytically and numerically that the direction and speed of front propagation is led by nonvariational dynamics...
January 2017: Physical Review. E
Evgeny P Zemskov, Mikhail A Tsyganov, Werner Horsthemke
We study waves with exponentially decaying oscillatory tails in a reaction-diffusion system with linear cross diffusion. To be specific, we consider a piecewise linear approximation of the FitzHugh-Nagumo model, also known as the Bonhoeffer-van der Pol model. We focus on two types of traveling waves, namely solitary pulses that correspond to a homoclinic solution, and sequences of pulses or wave trains, i.e., a periodic solution. The effect of cross diffusion on wave profiles and speed of propagation is analyzed...
January 2017: Physical Review. E
Takeaki Araki, Jumpei Nagura
We studied in-plane bistable alignments of nematic liquid crystals confined by two frustrated surfaces by means of Monte Carlo simulations of the Lebwohl-Lasher spin model. The surfaces are prepared with orientational checkerboard patterns, on which the director field is locally anchored to be planar yet orthogonal between the neighboring blocks. We found the director field in the bulk tends to be aligned along the diagonal axes of the checkerboard pattern, as reported experimentally [J.-H. Kim et al., Appl...
January 2017: Physical Review. E
A Papangelo, M Ciavarella
We study the adhesion of a surface with a 'dimple' which shows a mechanism for a bi-stable adhesive system in surfaces with spaced patterns of depressions, leading to adhesion enhancement, high dissipation and hysteresis. Recent studies were limited mainly to the very short range of adhesion (the so-called JKR regime), while we generalize the study to a Maugis cohesive model. A 'generalized Tabor parameter', given by the ratio of theoretical strength to elastic modulus, multiplied by the ratio of dimple width to depth has been found...
February 2017: Journal of the Royal Society, Interface
Lina Wu, Xu Wang, Jianqiang Zhang, Tian Luan, Emmanuelle Bouveret, Xiaomei Yan
Cell-based two-hybrid assays have been key players in identifying pairwise interactions, yet quantitative measurement of protein-protein interactions in vivo remains challenging. Here, we show that using relative reporter protein expression (RRPE), defined as the level of reporter expression normalized to that of the interacting protein, quantitative analysis of protein interactions in bacterial adenylate cyclase two-hybrid (BACTH) system can be achieved. A multicolor flow cytometer was used to measure simultaneously the expression levels of one of the two putative interacting proteins and the β-galactosidase (β-gal) reporter protein upon dual immunofluorescence staining...
February 7, 2017: Analytical Chemistry
Vincent Jaquet, Chieh Hsu, Attila Becskei
Bistability plays an important role to generate two stable states for alternative cell fates, or to promote cellular diversity and cell cycle oscillations. Positive feedback loops are necessary for the existence of bistability and ultrasensitive reactions in the loops broaden the parameter range of bistability. The broader parameter range a system's bistability covers, the more robust the two states are. It is challenging to determine the bistable range of a parameter because noise and transient processes induce transitions between the two states...
January 30, 2017: Integrative Biology: Quantitative Biosciences From Nano to Macro
Sergi Vela, Michael B Reardon, Charles E Jakobsche, Mark M Turnbull, Jordi Ribas, Juan J Novoa
Dithiazolyl (DTA)-based radicals have furnished many examples of organic spin-transition materials, some of them occurring with hysteresis and some others without. Here, we present a combined computational and experimental study aimed at deciphering the factors controlling the existence or absence of hysteresis by comparing the phase transitions of 4-cyanobenzo-1,3,2-dithiazolyl and 1,3,5-trithia-2,4,6- triazapentalenyl radicals, which are prototypical examples of non-bistable and bistable spin transitions, respectively...
January 26, 2017: Chemistry: a European Journal
Antje Jensch, Caterina Thomaseth, Nicole E Radde
BACKGROUND: Positive and negative feedback loops are ubiquitous motifs in biochemical signaling pathways. The mitogen-activated protein kinase (MAPK) pathway module is part of many distinct signaling networks and comprises several of these motifs, whose functioning depends on the cell line at hand and on the particular context. The maintainance of specificity of the response of the MAPK module to distinct stimuli has become a key paradigm especially in PC-12 cells, where the same module leads to different cell fates, depending on the stimulating growth factor...
January 25, 2017: BMC Systems Biology
Gonen Ashkenasy, Nathaniel Wagner, Rakesh Mukherjee, Indrajit Maity, Enrique Peacock-Lopez
Bistability and bifurcation, found in a wide range of biochemical networks, are central to the proper function of living systems. We investigate herein recent model systems that show bistable behavior based on non-enzymatic self-replication reactions. Such models have been used before for investigating catalytic growth, chemical logic operations, and additional processes of self-organization leading to complexification. By solving for their steady-state solutions using various analytical and numerical methods, we analyze how and when these systems yield bistability and bifurcation, and discover specific cases and conditions producing bistability...
January 23, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Nicolas Marsal, Lionel Weicker, Delphine Wolfersberger, Marc Sciamanna
We analyze the transition from convective to absolute dynamical instabilities in a nonlinear optical system forming patterns, i.e., a photorefractive crystal in a single feedback configuration. We demonstrate that the convective regime is directly related to the bistability area in which the homogeneous steady state coexists with a pattern solution. Outside this domain, the system exhibits either a homogeneous steady state or an absolute dynamical regime. We evidence that the bistability area can be greatly increased by adjusting the mirror tilt angle and/or by applying an external background illumination on the photorefractive crystal...
January 6, 2017: Physical Review Letters
Sten Madec, Jérôme Casas, Guy Barles, Christelle Suppo
Analytical modeling of predator-prey systems has shown that specialist natural enemies can slow, stop and even reverse pest invasions, assuming that the prey population displays a strong Allee effect in its growth. We aimed to formalize the conditions in which spatial biological control can be achieved by generalists, through an analytical approach based on reaction-diffusion equations. Using comparison principles, we obtain sufficient conditions for control and for invasion, based on scalar bistable partial differential equations...
January 17, 2017: Journal of Mathematical Biology
Martin Herder, Fabian Eisenreich, Aurelio Bonasera, Anna Grafl, Lutz Grubert, Michael Pätzel, Jutta Schwarz, Stefan Hecht
Among bistable photochromic molecules diarylethenes (DAEs) possess the distinct feature that upon photoisomerization they undergo a large modulation of their π-electronic system, accompanied by a marked shift of the HOMO/LUMO energies and hence oxidation/reduction potentials. In order to exploit such photoswitchable systems it is important to precisely adjust the absolute position of their HOMO and LUMO levels and to maximize the extent of the photoinduced shifts of these energy levels. Here, we present a comprehensive study detailing how variation of the substitution pattern of DAE compounds, in particular using strongly electron-accepting and chemically stable trifluoromethyl groups either in the periphery or at the reactive carbon atoms, allows for the precise tuning of frontier molecular orbital levels over a broad energy range and the generation of photoinduced shifts of more than 1 eV...
January 17, 2017: Chemistry: a European Journal
J Dugay, M Aarts, M Giménez-Marqués, T Kozlova, H W Zandbergen, E Coronado, H S J van der Zant
Future multifunctional hybrid devices might combine switchable molecules and 2D material-based devices. Spin-crossover compounds are of particular interest in this context since they exhibit bistability and memory effects at room temperature while responding to numerous external stimuli. Atomically thin 2D materials such as graphene attract a lot of attention for their fascinating electrical, optical, and mechanical properties, but also for their reliability for room-temperature operations. Here, we demonstrate that thermally induced spin-state switching of spin-crossover nanoparticle thin films can be monitored through the electrical transport properties of graphene lying underneath the films...
January 11, 2017: Nano Letters
Shannon A Zirbel, Kyler A Tolman, Brian P Trease, Larry L Howell
Compliant bistable mechanisms are monolithic devices with two stable equilibrium positions separated by an unstable equilibrium position. They show promise in space applications as nonexplosive release mechanisms in deployment systems, thereby eliminating friction and improving the reliability and precision of those mechanical devices. This paper presents both analytical and numerical models that are used to predict bistable behavior and can be used to create bistable mechanisms in materials not previously feasible for compliant mechanisms...
2016: PloS One
David N Lyttle, Jeffrey P Gill, Kendrick M Shaw, Peter J Thomas, Hillel J Chiel
Motor systems must adapt to perturbations and changing conditions both within and outside the body. We refer to the ability of a system to maintain performance despite perturbations as "robustness," and the ability of a system to deploy alternative strategies that improve fitness as "flexibility." Different classes of pattern-generating circuits yield dynamics with differential sensitivities to perturbations and parameter variation. Depending on the task and the type of perturbation, high sensitivity can either facilitate or hinder robustness and flexibility...
December 21, 2016: Biological Cybernetics
Christopher T Reinhard, Noah J Planavsky, Benjamin C Gill, Kazumi Ozaki, Leslie J Robbins, Timothy W Lyons, Woodward W Fischer, Chunjiang Wang, Devon B Cole, Kurt O Konhauser
The macronutrient phosphorus is thought to limit primary productivity in the oceans on geological timescales. Although there has been a sustained effort to reconstruct the dynamics of the phosphorus cycle over the past 3.5 billion years, it remains uncertain whether phosphorus limitation persisted throughout Earth's history and therefore whether the phosphorus cycle has consistently modulated biospheric productivity and ocean-atmosphere oxygen levels over time. Here we present a compilation of phosphorus abundances in marine sedimentary rocks spanning the past 3...
January 19, 2017: Nature
Suyi Li, K W Wang
Plants exhibit a variety of reversible motions, from the slow opening of pine cones to the impulsive closing of Venus flytrap leaves. These motions are achieved without muscles and they have inspired a wide spectrum of engineered materials and structures. This review summarizes the recent developments of plant-inspired adaptive structures and materials for morphing and actuation. We begin with a brief overview of the actuation strategies and physiological features associated to these plant movements, showing that different combinations of these strategies and features can lead to motions with different deformation characteristics and response speeds...
December 20, 2016: Bioinspiration & Biomimetics
Farzaneh Maleki, Attila Becskei
Bistability permits the co-existence of two distinct cell fates in a population of genetically identical cells. Noise induced transitions between two fates of a bistable system are difficult to calculate due to the intricate interplay between nonlinear dynamics and noise in bistable positive feedback loops. Here we opened multivariable feedback loops at the slowest variable to obtain the open-loop function and the fluctuations in the open-loop output. By the subsequent reclosing of the loop, we calculated the mean first passage time (MFPT) using the Fokker-Planck equation in good agreement with the exact stochastic simulation...
December 18, 2016: Journal of Theoretical Biology
José Méndez-González, Ricardo Femat
Peroxidase-oxidase is an enzymatic reaction that can exhibit dynamical scenarios such as bistability, sustained oscillations, and Shilnikov chaos. In this work, we apply the chemical reaction network theory approach to find kinetic constants such that the associated mass action kinetics ordinary differential equations induced by three four dimensional structurally different enzymatic reaction systems can support the same steady states for several chemical species despite differences in their chemical nature...
December 14, 2016: Journal of Chemical Physics
Tiejun Xiao
In this paper, stochastic thermodynamics of delayed bistable Langevin systems near coherence resonance is discussed. We calculate the heat dissipation rate and the information flow of a delayed bistable Langevin system under various noise intensities. Both the heat dissipation rate and the information flow are found to be bell-shaped functions of the noise intensity, which implies that coherence resonance manifests itself in the thermodynamic properties.
November 2016: Physical Review. E
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