Giuseppe Di Biase

A Stochastic Model for the HIV/AIDS Dynamic Evolution

This paper analyses the HIV/AIDS dynamic evolution as defined by CD4 levels, from a macroscopic point of view, by means of homogeneous semi-Markov stochastic processes. A large number of results have been obtained including the following conditional probabilities: an infected patient will be in state j after a time t given that she/he entered at time 0 (starting time) in state i; that she/he will survive up to a time t, given the starting state; that she/he will continue to remain in the starting state up to time t; that she/he reach stage j of the disease in the next transition, if the previous state was i and no state change occurred up to time t. The immunological states considered are based on CD4 counts and our data refer to patients selected from a series of 766 HIV-positive intravenous drug users.

Markov and semi-Markov option pricing models with arbitrage possibility

The aim of this paper is the presentation of new models for option pricing that are discrete in time and in the framework of Markov and semi-Markov processes as an alternative to the classical Cox-Rubinstein model, and that also allow the possibility of arbitrage. Both cases of European and American options are considered and possible extensions are given.

RNAIII Inhibiting Peptide (RIP) and Derivatives as Potential Tools for the Treatment of S. aureus Biofilm Infections.

S. aureus under the biofilm mode of growth is often related to several nosocomial infections, more frequently associated with indwelling medical devices (catheters, prostheses, portacaths or heart valves). As a biofilm, the biopolymer matrix provides an excellent growth medium, increasing the tolerance to antibiotics and host immune system. To date, the antimicrobial therapy alone is not effective. A novel strategy to prevent biofilm formation is based on the interference with the bacterial cell-cell communication, a process known as quorum sensing (QS) and mediated by the RNA-III-activating peptide (RAP) and its target protein TRAP (Target of RAP). The RNAIII inhibiting peptide (RIP) is able to inhibit S. aureus pathogenesis by disrupting QS mechanism competing with RAP, thus inhibiting the phosphorylation of TRAP. This alteration leads to a reduced adhesion and to the inhibition of RNAIII synthesis, with the subsequent suppression of toxins synthesis. The present paper will provide an overview on the activity and potential applications of RIP as biofilm inhibiting compound, useful in the management of S. aureus biofilm infections. Moreover, medicinal chemistry strategies have been examined to better understand which modifications and/or structure alterations were able to produce new derivatives of this QS inhibitor with an improved antibiofilm activity.

Semi-Markov Migration Models for Credit Risk

Credit risk is one of the most important contemporary problems for banks and insurance companies. Indeed, for banks, more than forty percent of the equities are necessary to cover this risk. Though this problem is studied by large rating agencies with substantial economic, social and financial tools, building stochastic models is nevertheless necessary to complete this descriptive orientation. This book presents a complete presentation of such a category of models using homogeneous and non-homogeneous semi-Markov processes developed by the authors in several recent papers. This approach provides a good method of evaluating the default risk and the classical VaR indicators used for Solvency II and Basel III governance rules. This book is the first to present a complete semi-Markov treatment of credit risk while also insisting on the practical use of the models presented here, including numerical aspects, so that this book is not only useful for scientific research but also to managers working in this field for banks, insurance companies, pension funds and other financial institutions.

The Input Evaluation of Generalized Bernoulli Processes for Salary Lines Construction by Means of Continuous Time Generalized Non-Homogeneous Semi-Markov Processes

Salary line forecasting assumes a relevant role in manpower and in pension funds Previously, the authors presented a generalized Bernoulli process, useful for forecasting the evolution of salary lines, taking into account the salary costs, the number of workers at each rank and the probability transitions between the ranks. The problem with applying this model is constructing the probability of transition between the grades. In this article, we will present a model that allows obtaining these probabilities by means of the solution of the evolution equation of a generalization of continuous time non-homogeneous semi-Markov processes.

Erratum: Future pricing through homogeneous semi-Markov processes: Errata

The original article to which this Erratum refers was published in Applied Stochastic Models in Business and Industry 2005;21 (3):241–249