Search results for "Extended model"

Strong-interaction Isospin-symmetry Breaking Within the Density Functional Theory

2015

The conventional Skyrme interaction is generalized by adding zero-range charge-symmetry-breaking and charge-independence-breaking terms, and the corresponding energy density functional is derived. It is shown that the extended model accounts for experimental values of mirror and triplet displacement energies (MDEs and TDEs) in sd-shell isospin triplets with, on average, about 100~keV precision using only two additional adjustable coupling constants. Moreover, the model is able to reproduce, for the first time, the A=4n versus A=4n+2 staggering of the TDEs.

An immune system model in discrete time based on the analogy with the central nervous system

1988

Jerne's model for the immune system formulated in terms of a neural network recently proposed by Weisbuch and Atlan is generalized to interactions with continuous coupling coefficients. It is shown that even the extended model can be solved analytically without the aid of computer simulations and exhibits one additional attractor, which corresponds to a configuration with high concentrations of active killer cells eventually causing death of the organism.

An approximation to maximum likelihood estimates in reduced models

1990

SUMMARY An approximation to the maximum likelihood estimates of the parameters in a model can be obtained from the corresponding estimates and information matrices in an extended model, i.e. a model with additional parameters. The approximation is close provided that the data are consistent with the first model. Applications are described to log linear models for discrete data, to models for multivariate normal distributions with special covariance matrices and to mixed discrete-continuous models.

2013

The motion energy sensor has been shown to account for a wide range of physiological and psychophysical results in motion detection and discrimination studies. It has become established as the standard computational model for retinal movement sensing in the human visual system. Adaptation effects have been extensively studied in the psychophysical literature on motion perception, and play a crucial role in theoretical debates, but the current implementation of the energy sensor does not provide directly for modelling adaptation-induced changes in output. We describe an extension of the model to incorporate changes in output due to adaptation. The extended model first computes a space-time r…

Ein Ansatz zur Erklärung der Kundenbindung auf Basis der Theorie des geplanten Verhaltens

2005

Traditional customer satisfaction and customer retention models are extended by integrating variables such as perceived action control or social norm. These constructs are suggested by the attitude theory as well as the theory of planned behaviour. The extended model is tested in an empirical study carried out in the movie theatre industry. The model provides an excellent explanation of customer retention, which is the target variable in the study. Implications are derived for satisfaction managers which focus on the social group when approaching a specific customer. Finally, an outline for further theoretical and empirical studies is given as well as some limitations of the proposed model.

Sensitivity to Initial Conditions in an Extended Activator--Inhibitor Model for the Formation of Patterns

2018

Despite simplicity, the synchronous cellular automaton [D.A. Young, Math. Biosci. 72, 51 (1984)] enables reconstructing basic features of patterns of skin. Our extended model allows studying the formatting of patterns and their temporal evolution also on the favourable and hostile environments. As a result, the impact of different types of an environment is accounted for the dynamics of patterns formation. The process is based on two diffusible morphogens, the short-range activator and the long-range inhibitor, produced by differentiated cells (DCs) represented as black pixels. For a neutral environment, the extended model reduces to the original one. However, even the reduced model is stat…

Assessing Frequency Domain Causality in Cardiovascular Time Series with Instantaneous Interactions

2009

Summary Background: The partial directed coherence (PDC) is commonly used to assess in the frequency domain the existence of causal relations between two time series measured in conjunction with a set of other time series. Although the multivariate autoregressive (MVAR) model traditionally used for PDC computation accounts only for lagged effects, instantaneous effects cannot be neglected in the analysis of cardiovascular time series. Objectives: We propose the utilization of an extended MVAR model for PDC computation, in order to improve the evaluation of frequency domain causality in the presence of zero-lag correlations among multivariate time series. Methods: A procedure for the identif…

Coherence functions of the electrical and the optical noises in monomodal packaged vertical cavity surface emitting lasers

2006

Calculations of the frequency noise spectra and of the coherence functions between the electrical and the optical noises for a single-mode packaged vertical surface emitting laser (VCSEL) are reported.A rate-equation model for an index guided VCSEL is used, implemented with the electrical noise model including the intrinsic device, the package and external bias network.The extended model works up to the laser relaxation frequency. The amplitude optical noise and its correlation with the frequency and electrical noises are also analysed. The influence on the calculated quantities of some electrical and laser parameters is evaluated. The results show that generally the frequency noise is corr…

The two-fluid extended model of superfluid helium

2019

In this paper we perform the first numerical comparison between the two main existing models of superfluid helium: the two-fluid model proposed by Landau and the one-fluid extended model proposed from the extended thermodynamics. The numerical experiments in this paper regard the profiles of the so-called normal and superfluid components in 2D counterflow turbulence.

Brand love and positive word of mouth : the moderating effects of experience and price

2016

Purpose This study aims to test and extend Carroll and Ahuvia’s (2006) model on the antecedents and outcomes of brand love by examining the moderating effects of experience and price on the relationship between brand love and offline word of mouth (WOM) and between brand love and electronic WOM (eWOM). Design/methodology/approach An online survey was conducted on Facebook, which generated 342 valid responses. The data were analyzed using partial least squares-structural equation modeling. Findings The results mainly support the model by confirming that the self-expressiveness of the brand and trust are positively associated with brand love. No association between hedonic product type and b…