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Lianchun Yu, Zhou Shen, Chen Wang, Yuguo Yu
Selective pressure may drive neural systems to process as much information as possible with the lowest energy cost. Recent experiment evidence revealed that the ratio between synaptic excitation and inhibition (E/I) in local cortex is generally maintained at a certain value which may influence the efficiency of energy consumption and information transmission of neural networks. To understand this issue deeply, we constructed a typical recurrent Hodgkin-Huxley network model and studied the general principles that governs the relationship among the E/I synaptic current ratio, the energy cost and total amount of information transmission...
2018: Frontiers in Cellular Neuroscience
Xujun Zheng, Yang Zhang, Ning Cao, Xin Li, Shuoqing Zhang, Renfeng Du, Haiying Wang, Zhenni Ye, Yan Wang, Fahe Cao, Haoran Li, Xin Hong, Andrew C-H Sue, Chuluo Yang, Wei-Guang Liu, Hao Li
Spin-spin interactions between two identical aromatic radicals have been studied extensively and utilized to establish supramolecular recognition. Here we report that spin-pairing interactions could also take place between two different π-electron radicals, namely a bipyridinium radical cation (BPY+• ) and a naphthalene-1,8:4,5-bis(dicarboximide) radical anion (NDI─• ). The occurrence of this type of previously unreported hetero radical-pairing interactions is attributed to enhancement effect of Coulombic attraction between these two radicals bearing opposite charges...
May 17, 2018: Nature Communications
Lijie Hao, Zhuoqin Yang, Jinzhi Lei
Long-term potentiation (LTP) is a specific form of activity-dependent synaptic plasticity that is a leading mechanism of learning and memory in mammals. The properties of cooperativity, input specificity, and associativity are essential for LTP; however, the underlying mechanisms are unclear. Here, based on experimentally observed phenomena, we introduce a computational model of synaptic plasticity in a pyramidal cell to explore the mechanisms responsible for the cooperativity, input specificity, and associativity of LTP...
2018: Frontiers in Computational Neuroscience
Tian Chen, Osama R Bilal, Kristina Shea, Chiara Daraio
In most macroscale robotic systems, propulsion and controls are enabled through a physical tether or complex onboard electronics and batteries. A tether simplifies the design process but limits the range of motion of the robot, while onboard controls and power supplies are heavy and complicate the design process. Here, we present a simple design principle for an untethered, soft swimming robot with preprogrammed, directional propulsion without a battery or onboard electronics. Locomotion is achieved by using actuators that harness the large displacements of bistable elements triggered by surrounding temperature changes...
May 15, 2018: Proceedings of the National Academy of Sciences of the United States of America
Liu-Suo Wang, Ning-Xi Li, Jing-Jia Chen, Xiao-Peng Zhang, Feng Liu, Wei Wang
A positive and a negative feedback loop can induce bistability and oscillation, respectively, in biological networks. Nevertheless, they are frequently interlinked to perform more elaborate functions in many gene regulatory networks. Coupled positive and negative feedback loops may exhibit either oscillation or bistability depending on the intensity of the stimulus in some particular networks. It is less understood how the transition between the two dynamic modes is modulated by the positive and negative feedback loops...
April 2018: Physical Review. E
Anatoly Kaznacheev, Evgeny Pozhidaev, Vladimir Rudyak, Alexander V Emelyanenko, Alexei Khokhlov
A biaxial surface potential Φ_{s} of smectic-C^{*} surface-stabilized ferroelectric liquid crystals (SSFLCs) is introduced in this paper to explain the experimentally observed electric-field dependence of polarization P[over ̃]_{cell}(E), in particular the shape of the static hysteresis loops. Our potential consists of three independent parts. The first nonpolar part Φ_{n} describes the deviation of the prime director n (which is the most probable orientation of the long molecular axes) from the easy alignment axis R, which is located in the boundary surface plane...
April 2018: Physical Review. E
S A Carvalho, M L Martins
Microorganisms and plants very commonly release toxic secondary chemical compounds (allelochemicals) that inhibit or kill sensitive strains or individuals from their own or other species. In this work we study a model that describes two species interacting through allelopathic suppression and competing for resources. Employing linear stability analysis, the conditions for coexistence or extinction of species in spatially homogeneous systems were determined. We found that the borders between the regimes of bistability, coexistence, and the extinction of the weaker by the stronger competitor, are altered by allelopathic interactions...
April 2018: Physical Review. E
Miguel A Rodríguez, Florian Denis-le Coarer, Ángel Valle
A first analysis of fluctuations of the light intensity of vertical-cavity surface-emitting lasers operating in a bistable regime reveals the presence of 1/f noise. In this regime the intensity fluctuates between two recently characterized states with residence times {τ_{1}} and {τ_{2}}. We identify three distinct processes. One of them presents a coherence enhancement phenomenon, and in the other two the distribution of residence times in one of the states follows either a power law P(τ_{1})∼τ_{1}^{-2} or P(τ_{2})∼τ_{2}^{-2}, and this is the cause of the 1/f shape in the spectral density of the intensity...
April 2018: Physical Review. E
Saeed Khan, Hakan E Türeci
We investigate the dynamics of a microwave-driven Josephson junction capacitively coupled to a lumped-element LC oscillator. In the regime of driving where the Josephson junction can be approximated as a Kerr oscillator, this minimal nonlinear system has been previously shown to exhibit a bistability in phase and amplitude. In the present study, we characterize the full phase diagram and show that besides a parameter regime exhibiting bistability, there is also a regime of self-oscillations characterized by a frequency comb in its spectrum...
April 13, 2018: Physical Review Letters
Marco Faggian, Francesco Ginelli, Francesco Marino, Giovanni Giacomelli
Experimental evidence of an absorbing phase transition, so far associated with spatiotemporal dynamics, is provided in a purely temporal optical system. A bistable semiconductor laser, with long-delayed optoelectronic feedback and multiplicative noise, shows the peculiar features of a critical phenomenon belonging to the directed percolation universality class. The numerical study of a simple, effective model provides accurate estimates of the transition critical exponents, in agreement with both theory and our experiment...
April 27, 2018: Physical Review Letters
Subhasish Baral, Rahul Roy, Narendra M Dixit
A fraction of chronic hepatitis C patients treated with direct-acting antivirals (DAAs) achieved sustained virological responses (SVR), or cure, despite having detectable viremia at the end of treatment (EOT). This observation, termed EOT+ /SVR, remains puzzling and precludes rational optimization of treatment durations. One hypothesis to explain EOT+ /SVR, the immunologic hypothesis, argues that the viral decline induced by DAAs during treatment reverses the exhaustion of cytotoxic T lymphocytes (CTLs), which then clear the infection after treatment...
May 9, 2018: Immunology and Cell Biology
István Molnár, Krisztina Kurin-Csörgei, István Szalai
Minimal bromate oscillators represent the simplest version of the oscillatory reactions based on the chemistry of the oxybromine species. Here, we present numerical and experimental evidence of the existence of reaction-diffusion waves in the ferroin catalyzed minimal bromate oscillator. The wave dynamics depend not only on the characteristic chemical timescales but also on those of the diffusive matter exchange which occurs between the reaction-diffusion medium and its environment. We show that the extended reactivity of the ferroin catalyst towards the oxybromine species plays an essential role in the observed phenomena...
May 9, 2018: Physical Chemistry Chemical Physics: PCCP
Teng Cao, Lan Wang, Zhouyuan Sun, Stephen A Engel, Sheng He
In bistable perception, constant input leads to alternating perception. The dynamics of the changing perception reflects the intrinsic dynamic properties of the "unconscious inferential" process in the brain. Under the same condition, individuals differ in how fast they experience the perceptual alternation. In this study, testing many forms of bistable perception in a large number of observers, we investigated the key question of whether there is a general and common mechanism or multiple and independent mechanisms that control the dynamics of the inferential brain...
2018: Frontiers in Psychology
Francesca Sangiuliano Intra, Arthur-Ervin Avramiea, Mona Irrmischer, Simon-Shlomo Poil, Huibert D Mansvelder, Klaus Linkenkaer-Hansen
Ongoing brain dynamics have been proposed as a type of "neuronal noise" that can trigger perceptual switches when viewing an ambiguous, bistable stimulus. However, no prior study has directly quantified how such neuronal noise relates to the rate of percept reversals. Specifically, it has remained unknown whether individual differences in complexity of resting-state oscillations-as reflected in long-range temporal correlations (LRTC)-are associated with perceptual stability. We hypothesized that participants with stronger resting-state LRTC in the alpha band experience more stable percepts, and thereby fewer perceptual switches...
2018: Frontiers in Human Neuroscience
Susan L Denham, Dávid Farkas, Raymond van Ee, Mihaela Taranu, Zsuzsanna Kocsis, Marina Wimmer, David Carmel, István Winkler
The dynamics of perceptual bistability, the phenomenon in which perception switches between different interpretations of an unchanging stimulus, are characterised by very similar properties across a wide range of qualitatively different paradigms. This suggests that perceptual switching may be triggered by some common source. However, it is also possible that perceptual switching may arise from a distributed system, whose components vary according to the specifics of the perceptual experiences involved. Here we used a visual and an auditory task to determine whether individuals show cross-modal commonalities in perceptual switching...
May 8, 2018: Scientific Reports
Axel Lange, Hans L Nemeschkal, Gerd B Müller
We present a cellular automaton-based model for threshold behaviors in vertebrate digit patterning and polydactyly formation. The rules of the model follow classical reactor-diffusion algorithms. Yet it is not physical diffusion that is taken as the required natural agent but the propagation of cellular states, which can be represented by the same differential equations. The bistable cellular states in the model correspond to mesenchymal limb bud cells that can be either "on" or "off" for the cartilage differentiation pathway...
April 25, 2018: Progress in Biophysics and Molecular Biology
Hai-Peng Chen, Ping-Ping Shi, Zhong-Xia Wang, Ji-Xing Gao, Wan-Ying Zhang, Cheng Chen, Yuan-Yuan Tang, Da-Wei Fu
Molecular bistable dielectric switches represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weights, and mechanical flexibility. However, most of these switches can only work at a very low temperature, extremely limiting their potential applications. Herein, three layered organic-inorganic hybrid perovskite-type compounds of the general formula A2BX4, [NH3(CH2)2Cl]2[CdCl3Br] (1), [NH3(CH2)2Cl]2[CdCl4] (2) and [NH3(CH2)2Cl]2[CdBr4] (3), which display sensitive dielectric switching reversibility and remarkable switching anti-fatigue, have been successfully designed...
May 8, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Olivier Maillet, Xin Zhou, Rasul R Gazizulin, Rob Ilic, Jeevak M Parpia, Olivier Bourgeois, Andrew D Fefferman, Eddy Collin
Advances in nanomechanics within recent years have demonstrated an always expanding range of devices, from top-down structures to appealing bottom-up MoS2 and graphene membranes, used for both sensing and component-oriented applications. One of the main concerns in all of these devices is frequency noise, which ultimately limits their applicability. This issue has attracted a lot of attention recently, and the origin of this noise remains elusive up to date [SansaNatNat2016]. In this Letter we present a new and very simple technique to measure frequency noise in nonlinear mechanical devices, based on the presence of bistability...
May 7, 2018: ACS Nano
Tommy Khoo, Feng Fu, Scott Pauls
In recent years, there has been growing interest in studying games on multiplex networks that account for interactions across linked social contexts. However, little is known about how potential cross-context interference, or spillover, of individual behavioural strategy impact overall cooperation. We consider three plausible spillover modes, quantifying and comparing their effects on the evolution of cooperation. In our model, social interactions take place on two network layers: repeated interactions with close neighbours in a lattice, and one-shot interactions with random individuals...
May 2, 2018: Scientific Reports
Imke Spöring, Sebastian Felgner, Matthias Preuße, Denitsa Eckweiler, Manfred Rohde, Susanne Häussler, Siegfried Weiss, Marc Erhardt
Flagellum-driven motility of Salmonella enterica serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of Salmonella , resulting in flagellated and nonflagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhD4 C2 with respect to proteolytic degradation...
May 1, 2018: MBio
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