Search results for "Quantitative"
showing 10 items of 2409 documents
Non-linear neuro-inspired circuits and systems: Processing and learning issues
2018
In this chapter the main elements useful for the design and realization of the neural architectures reported in the following chapters will be presented. Considering spiking and non-spiking neurons, the models used for implementing each of them, the synaptic models, the basic learning and plasticity algorithms and the network architectures will be introduced and analysed. The key elements that led to their selection and application in the developed neuro-inspired systems will be discussed briefly.
A window amplitude discriminator with adjustable upper and lower thresholds
1976
An amplitude window discriminator is described which permits selection of spikes from a multi-unit recording, provided the signal-to-noise ratio is high enough. The device can be built at relatively low cost and time. The circuitry permits analysis of the positive or the negative deflections of the recorded signals. In Part One of the circuitry, the signals are pre-amplified and may be inverted in polarity. In Part Two, the pulses are compared to a variable lower threshold voltage, and low amplitude noise is eliminated. Part Three depicts a logic circuit for elimination of disturbing high-amplitude signals, whose output delivers digital pulses, each corresponding to an original signal (e.g.…
Nuovo realismo e metodi di ricerca misti
2014
Il nuovo realismo ha evidenziato i limiti del costruttivismo sociale e del cosiddetto «pensiero debole», che rischia di sfociare nel nichilismo. Sono stati recentemente rimossi dei pregiudizi che impedivano di cogliere la realtà dei fatti educativi nella sua concreta evidenza. Tuttavia un’apertura alla prospettiva metafisica offrirebbe al nuovo realismo ulteriori spazi epistemologici. In tale senso il contributo del realismo critico potrebbe aiutare a superare l’artificiosa antinomia tra il ruolo attivo del soggetto conoscente e la rilevazione oggettiva dei fatti educativi. Se si realizzasse questa apertura la conoscenza scientifica e la conoscenza corrente non sarebbero più viste come anti…
Role of noise in a market model with stochastic volatility
2006
We study a generalization of the Heston model, which consists of two coupled stochastic differential equations, one for the stock price and the other one for the volatility. We consider a cubic nonlinearity in the first equation and a correlation between the two Wiener processes, which model the two white noise sources. This model can be useful to describe the market dynamics characterized by different regimes corresponding to normal and extreme days. We analyze the effect of the noise on the statistical properties of the escape time with reference to the noise enhanced stability (NES) phenomenon, that is the noise induced enhancement of the lifetime of a metastable state. We observe NES ef…
Spiking patterns emerging from wave instabilities in a one-dimensional neural lattice.
2003
The dynamics of a one-dimensional lattice (chain) of electrically coupled neurons modeled by the FitzHugh-Nagumo excitable system with modified nonlinearity is investigated. We have found that for certain conditions the lattice exhibits a countable set of pulselike wave solutions. The analysis of homoclinic and heteroclinic bifurcations is given. Corresponding bifurcation sets have the shapes of spirals twisting to the same center. The appearance of chaotic spiking patterns emerging from wave instabilities is discussed.
A note on finite-time Lyapunov dimension of the Rossler attractor
2018
For the R\"ossler system we verify Eden's conjecture on the maximum of local Lyapunov dimension. We compute numerically finite-time local Lyapunov dimensions on the R\"ossler attractor and embedded unstable periodic orbits. The UPO computation is done by Pyragas time-delay feedback control technique.
Data-independent acquisition strategies for quantitative proteomics
2013
In shotgun proteomics, data-dependent precursor acquisition (DDA) is widely used to profile protein components in complex samples. Although very popular, there are some inherent limitations to the DDA approach, such as irreproducible precursor ion selection, under-sampling and long instrument cycle times. Unbiased ‘data-independent acquisition’ (DIA) strategies try to overcome those limitations. In MSE, which is supported by Waters Q-TOF instrument platforms, such as the Synapt G2-S, a wide band pass filter is used for precursor selection. During acquisition, alternating MS scans are collected at low and high collision energy (CE), providing precursor and fragment ion information, respectiv…
Biproportional methods of structural change analysis: A typological survey
2004
International audience; Analysts often are interested in learning how much an exchange system has changed over time or how two different exchange systems differ. Identifying structural difference in exchange matrices can be performed using either 'directed' or 'undirected' methods. Directed methods are based on the computation and comparison of column- or row-normalizations of the matrices. The choice of row or column for the normalization implies a specific direction of the exchanges, so that the column-wise normalized results should not be compared to the row-wise normalized results. In this category fall the simple comparison of coefficient matrices and the causative method. Undirected m…
Visual information flow in Wilson-Cowan networks.
2020
In this paper, we study the communication efficiency of a psychophysically tuned cascade of Wilson-Cowan and divisive normalization layers that simulate the retina-V1 pathway. This is the first analysis of Wilson-Cowan networks in terms of multivariate total correlation. The parameters of the cortical model have been derived through the relation between the steady state of the Wilson-Cowan model and the divisive normalization model. The communication efficiency has been analyzed in two ways: First, we provide an analytical expression for the reduction of the total correlation among the responses of a V1-like population after the application of the Wilson-Cowan interaction. Second, we empiri…
A quantitative analysis of Educational Data through the Comparison between Hierarchical and Not-Hierarchical Clustering
2017
Many research papers have studied the problem of taking a set of data and separating it into subgroups through the methods of Cluster Analysis. However, the variables and parameters involved in Cluster Analysis have not always been outlined and criticized, especially in the field of Science Education. Moreover, in the field of Science Education, a comparison between two different Clustering methods is not discussed in the literature. Conceptions of students about modeling in physic are investigated by using an open-ended questionnaire. The questionnaire is analyzed through Clustering methods. The clustering results obtained by using the two methods are compared and show a good coherence bet…