concomitant coronary artery bypass surgery (cabg) in patients undergoing mitral valve replacement (mvr) has been shown to be an important risk factor for hospital mortality. we evaluated preoperative characteristics, postoperative complications, in-hospital mortality rate, and length of stay in hospital for patients undergoing concurrent cabg with mvr. preoperative and postoperative clinical da...

MOTIVATION The observed correlations between pairs of homologous protein sequences are typically explained in terms of a Markovian dynamic of amino acid substitution. This model assumes that every location on the protein sequence has the same background distribution of amino acids, an assumption that is incompatible with the observed heterogeneity of protein amino acid profiles and with the suc...

This paper formulates a stochastic optimal stopping model for the replacement of mainframe computer systems in the telecommunications industry. It describes the replacement behavior by focusing on unique features of computer systems, which are associated with technological development. The optimal stopping rule is the solution of a stochastic dynamic programming model that specifies the system ...

In this research, a model for optimal PM planning based on reliability is developed and solved for multi-component systems. In the proposed model, the type of PM actions for each inspection period is determined in such manner that the total weighted related costs are minimized while a minimum required system reliability is maintained. The planning horizon is divided into some inspections interv...

We examine a replacement system with discrete-time Markovian deterioration and finite state space {0, ..., N}. State 0 stands for a new system, and the higher the state the worse the system; a system in state N is considered to be in a bad state. We impose the condition that the fraction of replacements in state N should not be larger than some fixed number. We prove that a generalized control ...

Surfactant replacement therapy (SRT) involves instillation of a liquid-surfactant mixture directly into the lung airway tree. It is widely successful for treating surfactant deficiency in premature neonates who develop neonatal respiratory distress syndrome (NRDS). However, when applied to adults with acute respiratory distress syndrome (ARDS), early successes were followed by failures. This un...

prosthetic joint infection (pji) is a calamitous complication with high morbidity and substantial cost. the reported incidence is low but it is probably underestimated due to the difficulty in diagnosis. pji has challenged the orthopaedic community for several years and despite all the advances in this field, it is still a real concern with immense impact on patients, and the healthcare system....

Understanding the nature of the diffusion process is crucial for sustainable development of a new technology and product. This study introduces a replacement diffusion model that leads to a better understanding of the growth dynamics of a technology. The model operates in an environment with multiple competitors and overcomes the limitations of existing models. The model (1) consists of a diffu...

The block replacement policy with no replacement at failure means that a unit is always replaced at fixed time, but not replaced at failure. In this paper, the lifetime of the unit is assumed to be an uncertain variable, the model of expected cost per unit time following no replacement at failure policy is proposed, and the existence condition of the optimal replacement time is given. Furthermo...