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Bistability

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https://www.readbyqxmd.com/read/28097417/bistability-induced-by-generalist-natural-enemies-can-reverse-pest-invasions
#1
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
https://www.readbyqxmd.com/read/28093831/light-controlled-reversible-modulation-of-frontier-molecular-orbital-energy-levels-in-trifluoromethylated-diarylethenes
#2
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
https://www.readbyqxmd.com/read/28088556/regulation-of-docetaxel-sensitivity-in-prostate-cancer-cells-by-hsa-mir-125a-3p-via-modulation-of-mta1-signaling
#3
Jian-Zhou Liu, Feng-Yan Yin, Chang-You Yan, Hui Wang, Xiao-Hui Luo
OBJECTIVE: To identify the potential down-stream targets of hsa-miR-125a-3p, a mature form of miR-125a, during the pathogenesis of chemoresistance in prostate cancer (PCa). METHODS: Expression levels of hsa-miR-125a-3p was assessed in chemoresistant PCa tissues and experimentally-established chemoresistant cells using quantitative RT-PCR (qRT-PCR). The effect of hsa-miR-125a-3p knockdown or hsa-miR-125a-3p overexpression on the Dox-induced cell death was evaluated using apoptosis ELISA in chemosensitive PC-3 cells or in chemoresistant PC-3 cells (PC-3R)...
January 11, 2017: Urology
https://www.readbyqxmd.com/read/28073272/phase-transitions-in-spin-crossover-thin-films-probed-by-graphene-transport-measurements
#4
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
https://www.readbyqxmd.com/read/28067396/edge-effect-of-strained-bilayer-nanofilms-for-tunable-multistability-and-actuation
#5
N Hu, X Han, S Huang, H M Grover, X Yu, L N Zhang, I Trase, J X J Zhang, L Zhang, L X Dong, Z Chen
We employed both theoretical and computational models supported by experiments to study the multistable behavior of an edge-effect driven Si/Cr micro-claw. Our study showed that individual micro-claws demonstrate either monostability or bistability as the magnitude of the edge effect is varied.
January 9, 2017: Nanoscale
https://www.readbyqxmd.com/read/28053039/complex-visual-motion-representation-in-mouse-area-v1
#6
Ganna Palagina, Jochen F Meyer, Stelios M Smirnakis
: Rodent visual cortex has a hierarchical architecture similar to that of higher mammals (Coogan and Burkhalter, 1993; Marshel et al., 2011; Wang et al., 2012). Although notable differences exist between the species in terms or receptive field sizes and orientation map organization (Dräger, 1975; Gattass et al., 1987; Van den Bergh et al., 2010), mouse V1 is thought to respond to local orientation and visual motion elements rather than to global patterns of motion, similar to V1 in higher mammals (Niell and Stryker, 2008; Bonin et al...
January 4, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28045041/relaxation-oscillations-and-hierarchy-of-feedbacks-in-mapk-signaling
#7
Marek Kochańczyk, Paweł Kocieniewski, Emilia Kozłowska, Joanna Jaruszewicz-Błońska, Breanne Sparta, Michael Pargett, John G Albeck, William S Hlavacek, Tomasz Lipniacki
We formulated a computational model for a MAPK signaling cascade downstream of the EGF receptor to investigate how interlinked positive and negative feedback loops process EGF signals into ERK pulses of constant amplitude but dose-dependent duration and frequency. A positive feedback loop involving RAS and SOS, which leads to bistability and allows for switch-like responses to inputs, is nested within a negative feedback loop that encompasses RAS and RAF, MEK, and ERK that inhibits SOS via phosphorylation. This negative feedback, operating on a longer time scale, changes switch-like behavior into oscillations having a period of 1 hour or longer...
January 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28030588/bistable-mechanisms-for-space-applications
#8
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
https://www.readbyqxmd.com/read/28027601/hysteresis-in-myo-inositol-utilization-by-salmonella-typhimurium
#9
Jessica Hellinckx, Thilo M Fuchs
Growth of Salmonella enterica serovar Typhimurium strain 14028 with myo-inositol (MI) as the sole carbon and energy source is characterized by a bistable phenotype that manifests in a growth phenotype with an extraordinarily long and length-variable lag phase. However, in the presence of hydrogen carbonate, in the absence of IolR that represses the MI degradation pathway, or if cells are already adapted to minimal medium (MM) with MI, the lag phase is drastically shortened, and the bistable phenotype is abolished...
December 27, 2016: MicrobiologyOpen
https://www.readbyqxmd.com/read/28008214/displacement-sensing-based-on-resonant-frequency-monitoring-of-electrostatically-actuated-curved-micro-beams
#10
Naftaly Krakover, B Robert Ilic, Slava Krylov
The ability to control nonlinear interactions of suspended mechanical structures offers a unique opportunity to engineer rich dynamical behavior that extends the dynamic range and ultimate device sensitivity. We demonstrate a displacement sensing technique based on resonant frequency monitoring of curved, doubly clamped, bistable micromechanical beams interacting with a movable electrode. In this configuration, the electrode displacement influences the nonlinear electrostatic interactions, effective stiffness and frequency of the curved beam...
November 2016: Journal of Micromechanics and Microengineering: Structures, Devices, and Systems
https://www.readbyqxmd.com/read/28006011/a-precise-temperature-responsive-bistable-switch-controlling-yersinia-virulence
#11
Aaron Mischa Nuss, Franziska Schuster, Louisa Roselius, Johannes Klein, René Bücker, Katharina Herbst, Ann Kathrin Heroven, Fabio Pisano, Christoph Wittmann, Richard Münch, Johannes Müller, Dieter Jahn, Petra Dersch
Different biomolecules have been identified in bacterial pathogens that sense changes in temperature and trigger expression of virulence programs upon host entry. However, the dynamics and quantitative outcome of this response in individual cells of a population, and how this influences pathogenicity are unknown. Here, we address these questions using a thermosensing virulence regulator of an intestinal pathogen (RovA of Yersinia pseudotuberculosis) as a model. We reveal that this regulator is part of a novel thermoresponsive bistable switch, which leads to high- and low-invasive subpopulations within a narrow temperature range...
December 2016: PLoS Pathogens
https://www.readbyqxmd.com/read/28004255/robustness-flexibility-and-sensitivity-in-a-multifunctional-motor-control-model
#12
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
https://www.readbyqxmd.com/read/28002400/evolution-of-the-global-phosphorus-cycle
#13
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...
December 21, 2016: Nature
https://www.readbyqxmd.com/read/27997836/cell-division-flipping-the-mitotic-switches
#14
Wolfgang Zachariae, John J Tyson
Alternation between DNA replication in the mother cell (S phase) and equal partitioning of the replicated chromosomes to the daughter cells (M phase) during eukaryotic cell division is governed by switches that flip protein kinases on and off. New work reveals that the M-phase promoting kinase is opposed by a phosphatase that also participates in a bistable switching mechanism.
December 19, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27995902/plant-inspired-adaptive-structures-and-materials-for-morphing-and-actuation-a-review
#15
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
https://www.readbyqxmd.com/read/27993627/an-open-loop-approach-to-calculate-noise-induced-transitions
#16
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
https://www.readbyqxmd.com/read/27984903/steady-state-equivalence-among-autocatalytic-peroxidase-oxidase-reactions
#17
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
https://www.readbyqxmd.com/read/27982066/the-nature-of-photoinduced-phase-transition-and-metastable-states-in-vanadium-dioxide
#18
Zhensheng Tao, Faran Zhou, Tzong-Ru T Han, David Torres, Tongyu Wang, Nelson Sepulveda, Kiseok Chang, Margaret Young, Richard R Lunt, Chong-Yu Ruan
Photoinduced threshold switching processes that lead to bistability and the formation of metastable phases in photoinduced phase transition of VO2 are elucidated through ultrafast electron diffraction and diffusive scattering techniques with varying excitation wavelengths. We uncover two distinct regimes of the dynamical phase change: a nearly instantaneous crossover into an intermediate state and its decay led by lattice instabilities over 10 ps timescales. The structure of this intermediate state is identified to be monoclinic, but more akin to M2 rather than M1 based on structure refinements...
December 16, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27967182/heat-dissipation-and-information-flow-for-delayed-bistable-langevin-systems-near-coherence-resonance
#19
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
https://www.readbyqxmd.com/read/27967167/optical-wall-dynamics-induced-by-coexistence-of-monostable-and-bistable-spatial-regions
#20
V Odent, E Louvergneaux, M G Clerc, I Andrade-Silva
When nonequilibrium extended homogeneous systems exhibit multistability, it leads to the presence of domain walls between the existing equilibria. Depending on the stability of the steady states, the dynamics differs. Here, we consider the interface dynamics in the case of a spatially inhomogeneous system, namely, an optical system where the control parameter is spatially Gaussian. Then interfaces connect the monostable and the bistable nonuniform states that are associated with two distinct spatial regions...
November 2016: Physical Review. E
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