16,377 research outputs found
Memristive operation mode of a site-controlled quantum dot floating gate transistor
The authors gratefully acknowledge financial support from the European Union (FPVII (2007-2013) under Grant Agreement No. 318287 Landauer) as well as the state of Bavaria.We have realized a floating gate transistor based on a GaAs/AlGaAs heterostructure with site-controlled InAs quantum dots. By short-circuiting the source contact with the lateral gates and performing closed voltage sweep cycles, we observe a memristive operation mode with pinched hysteresis loops and two clearly distinguishable conductive states. The conductance depends on the quantum dot charge which can be altered in a controllable manner by the voltage value and time interval spent in the charging region. The quantum dot memristor has the potential to realize artificial synapses in a state-of-the-art opto-electronic semiconductor platform by charge localization and Coulomb coupling.Publisher PDFPeer reviewe
Inheritance and identification of SCAR marker linked to bacterial wilt-resistance in eggplant
In the present work, the combinations (F1) were crossed between highly resistant and susceptible to bacterial wilt eggplant parents and its F2, BC1 segregation population plants were inoculated with race1 of Ralstonia solanacearum in greenhouse. In this paper, we reported that the inheritance of bacterial wilt resistance in eggplant was controlled by a single dominant gene showing Mendelian inheritance model. In addition, a 762 bp molecular marker linked to a bacterial wilt-resistant gene of eggplant was screenedby the bulked segregant analysis (BSA) method and sequence characterized amplified region (SCAR) marker linked to bacterial wilt-resistance gene was also obtained. The genetic distance between this marker and the resistance gene is 3.33 c
Neuronal synchrony: peculiarity and generality
Synchronization in neuronal systems is a new and intriguing application of dynamical systems theory. Why are neuronal systems different as a subject for synchronization? (1) Neurons in themselves are multidimensional nonlinear systems that are able to exhibit a wide variety of different activity patterns. Their âdynamical repertoireâ includes regular or chaotic spiking, regular or chaotic bursting, multistability, and complex transient regimes. (2) Usually, neuronal oscillations are the result of the cooperative activity of many synaptically connected neurons (a neuronal circuit). Thus, it is necessary to consider synchronization between different neuronal circuits as well. (3) The synapses that implement the coupling between neurons are also dynamical elements and their intrinsic dynamics influences the process of synchronization or entrainment significantly. In this review we will focus on four new problems: (i) the synchronization in minimal neuronal networks with plastic synapses (synchronization with activity dependent coupling), (ii) synchronization of bursts that are generated by a group of nonsymmetrically coupled inhibitory neurons (heteroclinic synchronization), (iii) the coordination of activities of two coupled neuronal networks (partial synchronization of small composite structures), and (iv) coarse grained synchronization in larger systems (synchronization on a mesoscopic scale
Robustness and Enhancement of Neural Synchronization by Activity-Dependent Coupling
We study the synchronization of two model neurons coupled through a synapse
having an activity-dependent strength. Our synapse follows the rules of
Spike-Timing Dependent Plasticity (STDP). We show that this plasticity of the
coupling between neurons produces enlarged frequency locking zones and results
in synchronization that is more rapid and much more robust against noise than
classical synchronization arising from connections with constant strength. We
also present a simple discrete map model that demonstrates the generality of
the phenomenon.Comment: 4 pages, accepted for publication in PR
Cosmological Evolution of Interacting Dark Energy Models with Mass Varying Neutrinos
In this paper we consider the cosmological implications of dark energy models
with a coupled system of a dynamical scalar field (the quintessence) and the
neutrinos. By detailed numerical calculations we study the various
possibilities on the evolution and the fates of the universe in this class of
models. Our results show that due to the interaction with quintessence,
neutrinos could be dominant over the quintessence in the future universe,
however would eventually decay away.Comment: One typographical error corrected, references updated and
presentation improve
Temperature dependence of interlayer coupling in perpendicular magnetic tunnel junctions with GdOx barriers
Perpendicular magnetic tunnel junctions with GdOX tunneling barriers have
shown a unique voltage controllable interlayer magnetic coupling effect. Here
we investigate the quality of the GdOX barrier and the coupling mechanism in
these junctions by examining the temperature dependence of the tunneling
magnetoresistance and the interlayer coupling from room temperature down to 11
K. The barrier is shown to be of good quality with the spin independent
conductance only contributing a small portion, 14%, to the total room
temperature conductance, similar to AlOX and MgO barriers. The interlayer
coupling, however, shows an anomalously strong temperature dependence including
sign changes below 80 K. This non-trivial temperature dependence is not
described by previous models of interlayer coupling and may be due to the large
induced magnetic moment of the Gd ions in the barrier.Comment: 14 pages, 4 figure
Equilibrium Properties of Temporally Asymmetric Hebbian Plasticity
A theory of temporally asymmetric Hebb (TAH) rules which depress or
potentiate synapses depending upon whether the postsynaptic cell fires before
or after the presynaptic one is presented. Using the Fokker-Planck formalism,
we show that the equilibrium synaptic distribution induced by such rules is
highly sensitive to the manner in which bounds on the allowed range of synaptic
values are imposed. In a biologically plausible multiplicative model, we find
that the synapses in asynchronous networks reach a distribution that is
invariant to the firing rates of either the pre- or post-synaptic cells. When
these cells are temporally correlated, the synaptic strength varies smoothly
with the degree and phase of synchrony between the cells.Comment: 3 figures, minor corrections of equations and tex
Pillared two-dimensional metal-organic frameworks based on a lower-rim acid appended calix[4]arene
Solvothermal reactions of the lower-rim functionalized diacid calix[4]arene 25,27-bis(methoxycarboxylic acid)-26,28-dihydroxy-4-tert-butylcalix[4]arene (LHâ) with Zn(NOâ)ââą6HâO and the dipyridyl ligands 4,4/-bipyridyl (4,4/-bipy), 1,2-di(4-pyridyl)ethylene (DPE) or 4,4/-azopyridyl (4,4/-azopy) afforded a series of 2-D structures of the formulae {[Zn(4,4/-bipy)(L)]âą2ÂŒDEF}n (1), {[Znâ(L)(DPE)]âąDEF}n (2) and {[Zn(OHâ)â(L)(4,4/-azopy)]âąDEF}n (3) (DEF = diethylformamide)
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