We show analytically that the square of the drift in encoded position due to noise is proportional to time and inversely proportional to the number of oscillators. We also show there is a relatively fixed breakdown point, independent of many parameters of the model, Alisertib solubility dmso past which noise overwhelms the spatial signal. Based on this result, we show that a pair of oscillators are expected to maintain a stable grid for approximately t = 5 mu(3)/(4 pi sigma)(2) seconds where
mu is the mean period of an oscillator in seconds and sigma(2) its variance in seconds(2). We apply this criterion to recordings of individual persistent spiking neurons in postsubiculum (dorsal presubiculum) and layers III and V of entorhinal cortex, to subthreshold membrane potential oscillation recordings in layer II stellate cells of medial entorhinal cortex and to values from the literature regarding medial selleck inhibitor septum theta bursting cells. All oscillators examined have expected stability times far below those seen in experimental recordings of grid cells, suggesting the examined biological oscillators are unfit as a substrate for current implementations of oscillatory interference models. However, oscillatory interference models can tolerate small amounts of noise, suggesting the utility of circuit level effects which might reduce oscillator variability.
Further implications for grid cell models are LBH589 concentration discussed.”
“We have investigated the electrical characteristics of a “”model”" small-angle grain boundary (GB) in n-type direct silicon bonded wafers with intentional Au contamination. It is found that the Au aggregated at the GB can cause new acceptorlike states, developing a potential barrier. The density of Au-related GB states is about 1-2 X 10(12) cm(-2) eV(-1) in the energy range of E(c)-0.65-E(c)-0.33 eV. With the energy
level becoming deeper, the corresponding electron capture cross-section becomes larger, in the order of magnitude 10(-16)-10(-15) cm(2). It is believed that Au contamination has strong influence on the electrical properties of GB. These results are interesting for the GB engineering of n-type multicrystalline silicon solar cells for terrestrial application. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3471817]“
“For field emission from wide-band-gap semiconductor nanostructures, nonlinear plots on Fowler-Nordheim (FN) coordinates and unacceptably large field enhancement factors (beta(FN)) are often obtained by fitting based on FN equation. In the present work, the field-induced hot-electron emission model is developed and is found to give theoretical findings consistent with the experimental observation. The hot electrons are produced by heating effect of penetration field into the emitting tip of the nanostructure. This energy is expressed by effective electron temperature T(e), which is much higher than the temperature of bulk structure.