304 research outputs found
Non-Gaussian Resistance Noise near Electrical Breakdown in Granular Materials
The distribution of resistance fluctuations of conducting thin films with
granular structure near electrical breakdown is studied by numerical
simulations. The film is modeled as a resistor network in a steady state
determined by the competition between two biased processes, breaking and
recovery. Systems of different sizes and with different levels of internal
disorder are considered. Sharp deviations from a Gaussian distribution are
found near breakdown and the effect increases with the degree of internal
disorder. However, we show that in general this non-Gaussianity is related to
the finite size of the system and vanishes in the large size limit.
Nevertheless, near the critical point of the conductor-insulator transition,
deviations from Gaussianity persist when the size is increased and the
distribution of resistance fluctuations is well fitted by the universal
Bramwell-Holdsworth-Pinton distribution.Comment: 8 pages, 6 figures; accepted for publication on Physica
A Percolative Model of Soft Breakdown in Ultrathin Oxides
The degradation of ultrathin oxide layers in the presence of a stress voltage
is modeled in terms of two antagonist percolation processes taking place in a
random resistor network. The resistance and leakage current fluctuations are
studied by MonteCarlo simulations for voltages below the breakdown threshold.
An increase of excess noise together with a noticeable non-Gaussian behavior is
found in the pre-breakdown regime in agreement with experimental results.Comment: accepted for publication on Physica
The role of topology in electrical properties of bacteriorhodopsin and rat olfactory receptor I7
We report on electrical properties of the two sensing proteins:
bacteriorhodopsin and rat olfactory receptor OR-I7. As relevant transport
parameters we consider the small-signal impedance spectrum and the static
current-voltage characteristics. Calculations are compared with available
experimental results and the model predictability is tested for future
perspectives.Comment: 4 pages, 4 figure
Non-Gaussian Fluctuations in Biased Resistor Networks: Size Effects versus Universal Behavior
We study the distribution of the resistance fluctuations of biased resistor
networks in nonequilibrium steady states. The stationary conditions arise from
the competition between two stochastic and biased processes of breaking and
recovery of the elementary resistors. The fluctuations of the network
resistance are calculated by Monte Carlo simulations which are performed for
different values of the applied current, for networks of different size and
shape and by considering different levels of intrinsic disorder. The
distribution of the resistance fluctuations generally exhibits relevant
deviations from Gaussianity, in particular when the current approaches the
threshold of electrical breakdown. For two-dimensional systems we have shown
that this non-Gaussianity is in general related to finite size effects, thus it
vanishes in the thermodynamic limit, with the remarkable exception of highly
disordered networks. For these systems, close to the critical point of the
conductor-insulator transition, non-Gaussianity persists in the large size
limit and it is well described by the universal Bramwell-Holdsworth-Pinton
distribution. In particular, here we analyze the role of the shape of the
network on the distribution of the resistance fluctuations. Precisely, we
consider quasi-one-dimensional networks elongated along the direction of the
applied current or trasversal to it. A significant anisotropy is found for the
properties of the distribution. These results apply to conducting thin films or
wires with granular structure stressed by high current densities.Comment: 8 pages, 4 figures. Invited talk at the 18-th International
Conference on Noise and Fluctuations, 19-23 September 2005, Salamanc
Non-Gaussianity of resistance fluctuations near electrical breakdown
We study the resistance fluctuation distribution of a thin film near
electrical breakdown. The film is modeled as a stationary resistor networkunder
biased percolation. Depending on the value of the external current,on the
system sizes and on the level of internal disorder, the fluctuation
distribution can exhibit a non-Gaussian behavior. We analyze this
non-Gaussianity in terms of the generalized Gumbel distribution recently
introduced in the context of highly correlated systems near criticality. We
find that when the average fraction of defects approaches the random
percolation threshold, the resistance fluctuation distribution is well
described by the universal behavior of the Bramwell-Holdsworth-Pinton
distribution.Comment: 3 figures, accepted for publication on Semicond Sci Tec
Current voltage characteristics and excess noise at the trap filling transition in polyacenes
Experiments in organic semiconductors (polyacenes) evidence a strong super
quadratic increase of the current-voltage (I-V) characteristic at voltages in
the transition region between linear (Ohmic) and quadratic (trap free
space-charge-limited-current) behaviours. Similarly, excess noise measurements
at a given frequency and increasing voltages evidence a sharp peak of the
relative spectral density of the current noise in concomitance with the strong
super-quadratic I-V characteristics. Here we discuss the physical
interpretation of these experiments in terms of an essential contribution from
field assisted trapping-detrapping processes of injected carriers. To this
purpose, the fraction of filled traps determined by the I-V characteristics is
used to evaluate the excess noise in the trap filled transition (TFT) regime.
We have found an excellent agreement between the predictions of our model and
existing experimental results in tetracene and pentacene thin films of
different length in the range .Comment: 20 pg, 13 figures, in pres
Fluctuations of Complex Networks: Electrical Properties of Single Protein Nanodevices
We present for the first time a complex network approach to the study of the
electrical properties of single protein devices. In particular, we consider an
electronic nanobiosensor based on a G-protein coupled receptor. By adopting a
coarse grain description, the protein is modeled as a complex network of
elementary impedances. The positions of the alpha-carbon atoms of each amino
acid are taken as the nodes of the network. The amino acids are assumed to
interact electrically among them. Consequently, a link is drawn between any
pair of nodes neighboring in space within a given distance and an elementary
impedance is associated with each link. The value of this impedance can be
related to the physical and chemical properties of the amino acid pair and to
their relative distance. Accordingly, the conformational changes of the
receptor induced by the capture of the ligand, are translated into a variation
of its electrical properties. Stochastic fluctuations in the value of the
elementary impedances of the network, which mimic different physical effects,
have also been considered. Preliminary results concerning the impedance
spectrum of the network and its fluctuations are presented and discussed for
different values of the model parameters.Comment: 16 Pages and 10 Figures published in SPIE Proceedings of the II
International Symposium on Fluctuation and Noise, Maspalomas,Gran
Canaria,Spain, 25-28 May 200
Banks’ attitude to partnership as an antecedent of Open Banking platforms: structural determinants and effects on performance in the Italian context
The recent developments in regulation, in particular PSD2 and ICT technologies, are fostering the Open Banking phenomenon, a model of forced or voluntary collaboration based on the sharing of data and applications between subjects not necessarily affiliated, in order to develop, produce and distribute innovative and value-added financial products and services for the customer. Open Banking is still in its early stages, and the approach with which banks decide to interpret and adapt to the new PSD2 regulations is crucial to grasp the evolution of the structure and operativity of the financial system in the coming years, as well as the role that banks will play in it. Indeed, a positive banks’ attitude to partnership is a crucial factor for developing Open Banking ecosystems and platforms and deserves the attention of researchers.
In this paper, we investigate the attitude to partnership of a sample of 45 Italian banks, which allows us to better understand whether there exist conditions for creating Open Banking ecosystems. Furthermore, we explore the economic determinants of banks’ attitudes to partnership and its effect on performance. Results reveal a low current attitude to partnership of Italian banks, a factor that may hinder the formation of Open Banking ecosystems and platforms. The attitude to partnership tends to be low for larger and more capitalised banks, while the opposite occurs for smaller and less capitalised banks, which can be more inclined to participate in Open Banking platforms to compensate for possible constraints in size, resources and human capital. Overall, participation in Open Banking platforms can be justified by the positive effect of attitude to partnership on banks’ performance, as shown by our analysis
- …