Search results for "Statistical"

Overview and prerequisites of well-functioning Latvian national innovation system

2013

Analysis and understanding of the national innovation system can help policy-makers to identify strategies for improving innovative performance and overall competitiveness of the national economy. Nowadays we know too little about how to identify and measure specific problems in the system (if at all possible), despite several attempts to define them. Until now, little analysis on the Latvian innovation system was made. The paper aims to analyse the Latvian national innovation system and to provide a factors of well-functioning Latvian national innovation system. This research gives a possibility to researchers and policy-makers to investigate the mismatch between policies and problems and …

Statistical validation of investment decisions and transactions in financial markets

Inferring directionality of coupled dynamical systems using Gaussian process priors: Application on neurovascular systems

2022

Dynamical system theory has recently shown promise for uncovering causality and directionality in complex systems, particularly using the method of convergent cross mapping (CCM). In spite of its success in the literature, the presence of process noise raises concern about CCM's ability to uncover coupling direction. Furthermore, CCM's capacity to detect indirect causal links may be challenged in simulated unidrectionally coupled Rossler-Lorenz systems. To overcome these limitations, we propose a method that places a Gaussian process prior on a cross mapping function (named GP-CCM) to impose constraints on local state space neighborhood comparisons. Bayesian posterior likelihood and…

Tooth replacement rates in early chondrichthyans: a qualitative approach

2009

The continuous replacement of teeth throughout their lifetime is a common characteristic of most chondrichthyans. This process was already present in the earliest representatives of the group. It has been well established that different species of extant sharks show rapid tooth replacement rates; however, some authors have suggested that in early chondrichthyans this rate might have been much slower. Here we present a qualitative approach to analyse tooth replacement rates in the Early Devonian shark Leonodus carlsi, the earliest tooth-bearing shark known to date. For this, we have examined 1,103 isolated teeth from Celtiberia, Spain. Our study provides strong evidences of an extremely slow…

The effect of defect location on coating fragmentation patterns under biaxial tension

2005

Fragmentation of a coating possessing orthogonal preferential crack propagation directions is modeled for equibiaxial tensile loading. Two plausible cracking scenarios are compared, caused by flaws randomly distributed over the area of the coating or along the coating fragment edges. The two fragmentation scenarios considered are shown to yield qualitatively different fragment patterns.

Assessing Transfer Entropy in cardiovascular and respiratory time series: A VARFI approach

2021

In the study of complex biomedical systems represented by multivariate stochastic processes, such as the cardiovascular and respiratory systems, an issue of great relevance is the description of the system dynamics spanning multiple temporal scales. Recently, the quantification of multiscale complexity based on linear parametric models, incorporating autoregressive coefficients and fractional integration, encompassing short term dynamics and long-range correlations, was extended to multivariate time series. Within this Vector AutoRegressive Fractionally Integrated (VARFI) framework formalized for Gaussian processes, in this work we propose to estimate the Transfer Entropy, or equivalently G…

The Poisson Point Process

2020

Poisson point processes can be used as a cornerstone in the construction of very different stochastic objects such as, for example, infinitely divisible distributions, Markov processes with complex dynamics, objects of stochastic geometry and so forth.

Thermodynamics: Classical Framework

2016

This chapter starts with a summary of the thermodynamic potentials and the relationships between them which are obtained from Legendre transformation. This is followed by an excursion to some important global properties of materials such as specific heat, expansion coefficients and others. The thermodynamic relations provide the basis for a discussion of continuous changes of state which are illustrated by the Joule-Thomson effect and the Van der Waals gas. These are models which are more realistic than the ideal gas. The discussion of Carnot cycles leads to and illustrates the second and third laws of thermodynamics. The chapter closes with a discussion of entropy as a concave function of …

On the autocorrelation function of Rice processes for unsymmetrical doppler power spectral densities

2010

In this paper, we derive an analytical expression for the ACF of Rice processes in the general case of unsymmetrical Doppler power spectral densities. This expression, which is obtained based on the multidimensional Gaussian distribution approach, is shown to cover the ACF of Rayleigh processes as a special case. Various numerical examples are presented to illustrate the impact of the channel parameters on the ACF. Computer simulations, considering the von Mises distribution for the angle of arrivals, are also performed to check the validity of the analytical result. Finally, the analysis of the covariance spectrum is addressed.

A New Family of Deformations of Darboux-Pöschl-Teller Potentials

2004

The aim of this Letter is to present a new family of integrable functional-difference deformations of the Schrodinger equation with Darboux–Poschl–Teller potentials. The related potentials are labeled by two integers m and n, and also depend on a deformation parameter h. When h→ 0 the classical Darboux–Poschl–Teller model is recovered.