References of "Dauby, Pierre"
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See detailEffect of including a gas layer on the gel formation process during the drying of a polymer solution
Rabani, Ramin ULiege; Machrafi, Hatim ULiege; Dauby, Pierre ULiege

in The European Physical Journal E (2017), 40(89), 11579-3

In this paper, we study the influence of the upper gas layer on the drying and gelation of a polymer solution. The gel is formed due to the evaporation of the binary solution into (inert) air. A one ... [more ▼]

In this paper, we study the influence of the upper gas layer on the drying and gelation of a polymer solution. The gel is formed due to the evaporation of the binary solution into (inert) air. A one dimensional model is proposed, where the evaporation flux is more realistically described than in previous studies. The approach is based on general thermodynamic principles. A composition-dependent diffusion coefficient is used in the liquid phase and the local equilibrium hypothesis is introduced at the interface to describe the evaporation process. The results show that the high thickness of the gas layer reduces evaporation, thus leading to longer drying times. Our model is also compared with more phenomenological descriptions of evaporation, for which the mass flux through the interface is described by the introduction of a Peclet number. A global agreement is found for appropriate values of the Peclet numbers and our model can thus be considered as a tool allowing to link the value of the empirical Peclet number to the physics of the gas phase. Finally, in contrast with other models, our approach emphasizes the possibility of very fast gelation at the interface, which could prevent all Marangoni convection during the drying process. [less ▲]

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See detailA mathematical model of respiration under protective ventilation and extracorporeal CO2 removal therapy
Habran, Simon ULiege; Desaive, Thomas ULiege; MORIMONT, Philippe ULiege et al

Conference (2017, September 27)

The aim of the present study is to build a mathematical model of the respiratory system connected to an extracorporeal CO2 removal device (ECCO2RD) to optimize the gas exchanges efficiency. The model must ... [more ▼]

The aim of the present study is to build a mathematical model of the respiratory system connected to an extracorporeal CO2 removal device (ECCO2RD) to optimize the gas exchanges efficiency. The model must be simple enough to provide rapid solutions and to estimate specific parameters from available clinical data. But it also must be complex enough to be able to simulate the respiratory system when protective ventilation is used and when this system is assisted by an ECCO2RD. [less ▲]

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See detailA multiscale model of the human cardiovascular system can account for the Frank-Starling effect on vascular filling therapy
Kosta, Sarah ULiege; Pironet, Antoine; Negroni, Jorge et al

Poster (2017, February 01)

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See detailMultiscale model of the human cardiovascular system: Description of heart failure and comparison of contractility indices
Kosta, Sarah ULiege; Negroni, Jorge; Lascano, Elena et al

in Mathematical Biosciences (2017), 284

A multiscale model of the cardiovascular system is presented. Hemodynamics is described by a lumped parameter model, while heart contraction is described at the cellular scale. An electrophysiological ... [more ▼]

A multiscale model of the cardiovascular system is presented. Hemodynamics is described by a lumped parameter model, while heart contraction is described at the cellular scale. An electrophysiological model and a mechanical model were coupled and adjusted so that the pressure and volume of both ventricles are linked to the force and length of a half-sarcomere. Particular attention was paid to the extreme values of the sarcomere length, which must keep physiological values. This model is able to reproduce healthy behavior, preload variations experiments, and ventricular failure. It also allows to compare the relevance of standard cardiac contractility indices. This study shows that the theoretical gold standard for assessing cardiac contractility, namely the end-systolic elastance, is actually load-dependent and therefore not a reliable index of cardiac contractility. [less ▲]

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See detailSelf-assembly by multi-drop evaporation of carbon-nanotube droplets on a polycarbonate substrate
Machrafi, Hatim ULiege; Minetti, C.; Dauby, Pierre ULiege et al

in Physica E: Low-Dimensional Systems and Nanostructures (2017), 85

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See detailTemperature, geometry, and bifurcations in the numerical modeling of the cardiac mechano-electric feedback.
Collet, A.; Bragard, J.; Dauby, Pierre ULiege

in Chaos (Woodbury, N.Y.) (2017), 27(9), 093924

This article characterizes the cardiac autonomous electrical activity induced by the mechanical deformations in the cardiac tissue through the mechano-electric feedback. A simplified and qualitative model ... [more ▼]

This article characterizes the cardiac autonomous electrical activity induced by the mechanical deformations in the cardiac tissue through the mechano-electric feedback. A simplified and qualitative model is used to describe the system and we also account for temperature effects. The analysis emphasizes a very rich dynamics for the system, with periodic solutions, alternans, chaotic behaviors, etc. The possibility of self-sustained oscillations is analyzed in detail, particularly in terms of the values of important parameters such as the dimension of the system and the importance of the stretch-activated currents. It is also shown that high temperatures notably increase the parameter ranges for which self-sustained oscillations are observed and that several attractors can appear, depending on the location of the initial excitation of the system. Finally, the instability mechanisms by which the periodic solutions are destabilized have been studied by a Floquet analysis, which has revealed period-doubling phenomena and transient intermittencies. [less ▲]

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See detailPractical identifiability analysis of a minimal cardiovascular system model.
Pironet, Antoine; Docherty, Paul D.; Dauby, Pierre ULiege et al

in Computer Methods & Programs in Biomedicine (2017)

BACKGROUND AND OBJECTIVE: Parameters of mathematical models of the cardiovascular system can be used to monitor cardiovascular state, such as total stressed blood volume status, vessel elastance and ... [more ▼]

BACKGROUND AND OBJECTIVE: Parameters of mathematical models of the cardiovascular system can be used to monitor cardiovascular state, such as total stressed blood volume status, vessel elastance and resistance. To do so, the model parameters have to be estimated from data collected at the patient's bedside. This work considers a seven-parameter model of the cardiovascular system and investigates whether these parameters can be uniquely determined using indices derived from measurements of arterial and venous pressures, and stroke volume. METHODS: An error vector defined the residuals between the simulated and reference values of the seven clinically available haemodynamic indices. The sensitivity of this error vector to each model parameter was analysed, as well as the collinearity between parameters. To assess practical identifiability of the model parameters, profile-likelihood curves were constructed for each parameter. RESULTS: Four of the seven model parameters were found to be practically identifiable from the selected data. The remaining three parameters were practically non-identifiable. Among these non-identifiable parameters, one could be decreased as much as possible. The other two non-identifiable parameters were inversely correlated, which prevented their precise estimation. CONCLUSIONS: This work presented the practical identifiability analysis of a seven-parameter cardiovascular system model, from limited clinical data. The analysis showed that three of the seven parameters were practically non-identifiable, thus limiting the use of the model as a monitoring tool. Slight changes in the time-varying function modeling cardiac contraction and use of larger values for the reference range of venous pressure made the model fully practically identifiable. [less ▲]

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See detailEffect of citrate anticoagulation on CO2 extraction during low flow extracorporeal veno-venous CO2 removal therapy
MORIMONT, Philippe ULiege; Habran, Simon ULiege; Hubert, Romain et al

in Intensive Care Medicine Experimental (2016), 4

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See detailA Comparison between four Techniques to Measure Cardiac Output
Pironet, Antoine ULiege; Dauby, Pierre ULiege; Chase, J. Geoffrey et al

in Proceedings of the 38th International Conference of the IEEE Engineering in Medicine and Biology Society (2016, August 17)

Cardiac output is an important variable when monitoring hemodynamic status. In particular, changes in cardiac output represent the goal of several circulatory management therapies. Unfortunately, cardiac ... [more ▼]

Cardiac output is an important variable when monitoring hemodynamic status. In particular, changes in cardiac output represent the goal of several circulatory management therapies. Unfortunately, cardiac output is very difficult to estimate, either in experimental or clinical settings. The goal of this work is to compare four techniques to measure cardiac output: pressure-volume catheter, aortic flow probe, thermodilution, and the PiCCO monitor. These four techniques were simultaneously used during experiments of fluid and endotoxin administration on 7 pigs. Findings show that, first, each individual technique is precise, with a relative coefficient of repeatability lower than 7 %. Second, 1 cardiac output estimate provided by any technique relates poorly to the estimates from the other 3, even if there is only small bias between the techniques. Third, changes in cardiac output detected by one technique are only detected by the others in 62 to 100 % of cases. This study confirms the difficulty of obtaining a reliable clinical cardiac output measurement. Therefore, several measurements using different techniques should be performed, if possible, and all such should be treated with caution. [less ▲]

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See detailA Comparison between four Techniques to Measure Cardiac Output
Pironet, Antoine ULiege; Dauby, Pierre ULiege; Chase, J. Geoffrey et al

Poster (2016, August 17)

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See detailModel-Based Decision Support Algorithm to Guide Fluid Resuscitation
Pironet, Antoine ULiege; Dauby, Pierre ULiege; MORIMONT, Philippe ULiege et al

in IFAC-PapersOnLine (2016, July 26), 49(5), 224-229

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See detailModel-Based Decision Support Algorithm to Guide Fluid Resuscitation
Pironet, Antoine ULiege; Dauby, Pierre ULiege; MORIMONT, Philippe ULiege et al

Conference (2016, June 02)

Fluid resuscitation is the first choice therapy for sepctic shock. However, fluid infusion only increases cardiac output in approximately 50 % of cases, while an excess of fluid can have harmful effects ... [more ▼]

Fluid resuscitation is the first choice therapy for sepctic shock. However, fluid infusion only increases cardiac output in approximately 50 % of cases, while an excess of fluid can have harmful effects. Therefore, clinicians are looking for indices to predict the effect of fluid infusion on cardiac output, before giving fluid. In this work, a minimal mathematical model of the cardiovascular system is used, representing the heart, an artery and a vein. The nine model parameters, including total stressed blood volume, are identified from experimental data. The experimental data was recorded during three 500 ml fluid infusions on two pigs infected with endotoxin, to simulate septic shock. The total stressed blood volume parameter is negatively associated with the change in cardiac output after fluid infusion, as observed in previous studies. Subsequently, an algorithm is proposed to guide fluid resuscitation, based on the value of this parameter. The use of the algorithm results in 60 % less fluid being given with virtually no effect on cardiac output. The decision algorithm has the potential to be used in human clinical trials since the data required for parameter identification can be obtained in an intensive care unit. [less ▲]

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See detailHeart failure assessment with a multiscale model
Negroni, Jorge; Cabrera-Fischer, Edmundo; Kosta, Sarah ULiege et al

Poster (2016, April 21)

Many cardiac diseases lead to heart failure (HF) causing increasing morbidity and mortality worldwide. Several alterations at the myocyte level have been identified, but their specific influence on ... [more ▼]

Many cardiac diseases lead to heart failure (HF) causing increasing morbidity and mortality worldwide. Several alterations at the myocyte level have been identified, but their specific influence on contractile and hemodynamic impairment is not yet clear. Mathematical modeling is a tool to address this issue enabling the analysis of individual myocyte changes on the overall circulatory response. Some myocyte models have been able to reproduce the impact of HF on experimentally detected myocyte components (1), but their integration into a ventricular model forming part of a multiscale circulatory approach has not been fully undertaken. Thus, the aim of this study is to compare the experimental hemodynamic and regional contractile response to acute HF versus a multiscale model based on a human myocyte representation. The experimentally-validated multiscale model shows adequate coupling between myocyte-derived left ventricular chamber and circulatory properties , and would be useful to predict the contractile and hemodynamic response to HF changes in myocyte variables. [less ▲]

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See detailParameter Correlation Analysis in Four Mathematical Models of Left Ventricular Relaxation
Pironet, Antoine ULiege; MORIMONT, Philippe ULiege; Dauby, Pierre ULiege et al

in 14th Belgian Day on Biomedical Engineering (2016, March 04)

Detailed reference viewed: 19 (3 ULiège)