49 documents found, page 1 of 5
An analytic method to determine the optimal time for the induction phase of ane...
Zaitri, Mohamed A.; Silva, Cristiana J.; Torres, Delfim F. M.We obtain an analytical solution for the time-optimal control problem in the induction phase of anesthesia. Our solution is shown to align numerically with the results obtained from the conventional shooting method. The induction phase of anesthesia relies on a pharmacokinetic/pharmacodynamic (PK/PD) model proposed by Bailey and Haddad in 2005 to regulate the infusion of propofol. In order to evaluate our appro...
Evaluating COVID-19 in Portugal: Bootstrap confidence interval
Tedim, Sofia; Afreixo, Vera; Felgueiras, Miguel; Leitão, Rui Pedro; Pinheiro, Sofia J.; Silva, Cristiana J.In this paper, we consider a compartmental model to fit the real data of confirmed active cases with COVID-19 in Portugal, from March 2, 2020 until September 10, 2021 in the Primary Care Cluster in Aveiro region, ACES BV, reported to the Public Health Unit. The model includes a deterministic component based on ordinary differential equations and a stochastic component based on bootstrap methods in regression. T...
Mathematical models and optimal control in mosquito transmitted diseases
Ghaffari, Peyman; Silva, Cristiana J.; Torres, Delfim F. M.Malaria is a life threatening disease, entirely preventable and treatable, provided the currently recommended interventions are properly implemented. These interventions include vector control through the use of insecticide-treated nets (ITNs). However, ITN possession does not necessarily translate into use. Human behavior change interventions, including information, education, communication (IEC) campaigns and...
A multiobjective optimization approach to pulmonary rehabilitation effectivenes...
Cabral, Jorge; Afreixo, Vera; Silva, Cristiana J.; Tavares, Ana Helena; Marques, AldaChronic obstructive pulmonary disease (COPD) is a common disease that accounts for a significant individualand societal burden. Pulmonary rehabilitation (PR) is a key management strategy but it is highly inaccessible, makingprioritisation highly needed. This study aimed to determine and optimize predictive models of PR outcomes and builda tool to help healthcare professionals in their clinical decision-making a...
Editorial for the special issue of axioms “Calculus of variations, optimal cont...
Martins, Natália; Almeida, Ricardo; Silva, Cristiana J.; Ammi, Moulay Rchid SidiNo abstract available.
Model-free based control of a HIV/AIDS prevention model
Michel, Loïc; Silva, Cristiana J.; Torres, Delfim F. M.Controlling an epidemiological model is often performed using optimal control theory techniques for which the solution depends on the equations of the controlled system, objective functional and possible state and/or control constraints. In this paper, we propose a model-free control approach based on an algorithm that operates in 'real-time' and drives the state solution according to a direct feedback on the s...
Stability and optimal control of a delayed HIV/AIDS-PrEP model
Silva, Cristiana J.In this paper, we propose a time-delayed HIV/AIDS-PrEP model which takes into account the delay on pre-exposure prophylaxis (PrEP) distribution and adherence by uninfected persons that are in high risk of HIV infection, and analyze the impact of this delay on the number of individuals with HIV infection. We prove the existence and stability of two equilibrium points, for any positive time delay. After, an optim...
Mathematical analysis of a hybrid model: impacts of individual behaviors on the...
Cantin, Guillaume; Silva, Cristiana J.; Banos, ArnaudIn this paper, we investigate the well-posedness and dynamics of a class of hybrid models, obtained by coupling a system of ordinary differential equations and an agent-based model. These hybrid models intend to integrate the microscopic dynamics of individual behaviors into the macroscopic evolution of various population dynamics models, and can be applied to a great number of complex problems arising in econo...
Complex network model for COVID-19: human behavior, pseudo-periodic solutions a...
Silva, Cristiana J.; Cantin, Guillaume; Cruz, Carla; Fonseca-Pinto, Rui; Passadouro, Rui; Santos, Estevão Soares dos; Torres, Delfim F. M.We propose a mathematical model for the transmission dynamics of SARS-CoV-2 in a homogeneously mixing non constant population, and generalize it to a model where the parameters are given by piecewise constant functions. This allows us to model the human behavior and the impact of public health policies on the dynamics of the curve of active infected individuals during a COVID-19 epidemic outbreak. After proving...
A SIQRB delayed model for cholera and optimal control treatment
Lemos-Paião, Ana P.; Maurer, Helmut; Silva, Cristiana J.; Torres, Delfim F. M.We improve a recent mathematical model for cholera by adding a time delay that represents the time between the instant at which an individual becomes infected and the instant at which he begins to have symptoms of cholera disease. We prove that the delayed cholera model is biologically meaningful and analyze the local asymptotic stability of the equilibrium points for positive time delays. An optimal control pr...