Replicated INAR(1) processes

Replicated time series are a particular type of repeated measures, which consist of time-sequences of measurements taken from several subjects (experimental units). We consider independent replications of count time series that are modelled by first-order integer-valued autoregressive processes, INAR(1). In this work, we propose several estimation methods using the classical and the Bayesian approaches and both in time and frequency domains. Furthermore, we study the asymptotic properties of the estimators. The methods are illustrated and their performance is compared in a simulation study. Finally, the methods are applied to a set of observations concerning sunspot data.PRODEP II

Estimation and forecasting in SUINAR(1) model

This work considers a generalization of the INAR(1) model to the panel data first order Seemingly Unrelated INteger AutoRegressive Poisson model, SUINAR(1). It presents Bayesian and classical methodologies to estimate the parameters of Poisson SUINAR(1) model and to forecast future observations of the process. In particular, prediction intervals for forecasts - classical approach - and HPD prediction intervals - Bayesian approach - are derived. A simulation study is provided to give additional insight into the finite sample behaviour of the parameter estimates and forecasts

Breaking democracy with non renormalizable mass terms

The exact democratic structure for the quark mass matrix, resulting from the action of the family symmetry group $A_{3L}\times A_{3R}$, is broken by the vaccum expectation values of heavy singlet fields appearing in non renormalizable dimension 6 operators. Within this specific context of breaking of the family symmetry we formulate a very simple ansatz which leads to correct quark masses and mixings.Comment: 6 pages, RevTe

The present development of time service in Brazil, with the application of the TV line-10 method for coordination and synchronization of atomic clocks

Various methods presently used for the dissemination of time at several levels of precision are described along with future projects in the field. Different aspects of time coordination are reviewed and a list of future laboratories participating in a National Time Scale will be presented. A Brazilian Atomic Time Scale will be obtained from as many of these laboratories as possible. The problem of intercomparison between the Brazilian National Time Scale and the International one will be presented and probable solutions will be discussed. Needs related to the TV Line-10 method will be explained and comments will be made on the legal aspects of time dissemination throughout the country

A Framework for Trusted Services

An existing challenge when selecting services to be used in a service- based system is to be able to distinguish between good and bad services. In this paper we present a trust-based service selection framework. The framework uses a trust model that calculates the level of trust a user may have with a service based on past experience of the user with the service and feedback about the service received from other users. The model takes into account different levels of trust among users, different relationships between users, and different levels of importance that a user may have for certain quality aspects of a service. A prototype tool has been implemented to illustrate and evaluate the work. The trust model has been evaluated in terms of its capacity to adjust itself due to changes in user ratings and its robustness

Tree-level metastability bounds for the most general two Higgs doublet model

Within two Higgs doublet models, it is possible that the current vacuum is not the global minimum, in which case it could possibly decay at a later stage. We discuss the tree-level conditions which must be obeyed by the most general scalar potential in order to preclude that possibility. We propose a new procedure which is not only more general but also easier to implement than the previously published one, including CP conserving as well as CP violating scalar sectors. We illustrate these conditions within the context of the Z2 model, softly broken by a complex, CP violating parameter.Comment: RevTex, 13 pages, 3 figure

On Computing Minimum Unsatisfiable Cores

Certifying the correctness of a SAT solver is straightforward for satisfiable instances of SAT. Given