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Peer Reviewed
See detailA computational solid and fluid mechanical analysis of CAD-versus micro-CT-based models of regular Ti6Al4V scaffolds for bone tissue engineering
Truscello, Silvia; Kerckhofs, Greet ULg; Moesen, Maarten et al

in Histology and Histopathology (2011)

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See detailComputational Study Of Colipase Interaction With Lipid Droplets And Bile Salt Micelles
Kerfelec, Brigitte; Allouche, Maya; Colin, Damien et al

in Proteins-Structure Function and Bioinformatics (2008), 73(4), 828-38

Colipase is a key element in the lipase-catalyzed hydrolysis of dietary lipids. Although devoid of enzymatic activity, colipase promotes the pancreatic lipase activity in physiological intestinal ... [more ▼]

Colipase is a key element in the lipase-catalyzed hydrolysis of dietary lipids. Although devoid of enzymatic activity, colipase promotes the pancreatic lipase activity in physiological intestinal conditions by anchoring the enzyme at the surface of lipid droplets. Analysis of structures of NMR colipase models and simulations of their interactions with various lipid aggregates, lipid droplet, and bile salt micelle, were carried out to determine and to map the lipid binding sites on colipase. We show that the micelle and the oil droplet bind to the same side of colipase 3D structure, mainly the hydrophobic fingers. Moreover, it appears that, although colipase has a single direction of interaction with a lipid interface, it does not bind in a specific way but rather oscillates between different positions. Indeed, different NMR models of colipase insert different fragments of sequence in the interface, either simultaneously or independently. This supports the idea that colipase finger plasticity may be crucial to adapt the lipase activity to different lipid aggregates. [less ▲]

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See detailComputational Study Of Lipid-Destabilizing Protein Fragments: Towards A Comprehensive View Of Tilted Peptides
Lins, Laurence ULg; Charloteaux, Benoît ULg; Thomas, Annick ULg et al

in Proteins-Structure Function and Genetics (2001), 44(4), 435-47

Tilted peptides are short sequence fragments (10-20 residues long) that possess an asymmetric hydrophobicity gradient along their sequence when they are helical. Due to this gradient, they adopt a tilted ... [more ▼]

Tilted peptides are short sequence fragments (10-20 residues long) that possess an asymmetric hydrophobicity gradient along their sequence when they are helical. Due to this gradient, they adopt a tilted orientation towards a single lipid/water interface and destabilize the lipids. We have detected those peptides in many different proteins with various functions. While being all tilted-oriented at a single lipid/water interface, no consensus sequence can be evidenced. In order to better understand the relationships between their lipid-destabilizing activity and their properties, we used IMPALA to classify the tilted peptides. This method allows the study of interactions between a peptide and a modeled lipid bilayer using simple restraint functions designed to mimic some of the membrane properties. We predict that tilted peptides have access to a wide conformational space in membranes, in contrast to transmembrane and amphipathic helices. In agreement with previous studies, we suggest that those metastable configurations could lead to the perturbation of the acyl chains organization and could be a general mechanism for lipid destabilization. Our results further suggest that tilted peptides fall into two classes: those from proteins acting on membrane behave differently than destabilizing fragments from interfacial proteins. While the former have equal access to the two layers of the membrane, the latter are confined within a single lipid layer. This could be in relation with the organization of lipid substrate on which the peptides physiologically act. [less ▲]

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See detailComputational Study Of Nisin Interaction With Model Membrane
Lins, Laurence ULg; Ducarme, P.; Breukink, E. et al

in Biochimica et Biophysica Acta-Biomembranes (1999), 1420(1-2), 111-20

Nisin is a 34-residue lantibiotic widely used as food preservative. Its mode of action on the bacterial cytoplasmic membrane is unclear. It should form ion channels but a molecular description of the ... [more ▼]

Nisin is a 34-residue lantibiotic widely used as food preservative. Its mode of action on the bacterial cytoplasmic membrane is unclear. It should form ion channels but a molecular description of the interaction between nisin and phospholipids is lacking. The interactions between nisin and a membrane and the influence of phospholipids are here analysed by molecular modelling. The NMR structures of nisin in a micellar environment were previously determined (Van den Hooven et al., Eur. J. Biochem. 235 (1996) 382-393) Those structures were used to start with. They were refined by running a Monte Carlo procedure at a model lipid/water interface. It was shown that nisin is adsorbing onto the interface, with its N-terminal moiety more deeply inserted in lipids than the C-end, indicating distinct hydrophobic properties of the N- and C-domains. Therefore, we suggest that the N-terminal part is implied in the insertion of nisin in lipids, while the C-terminal moiety could be involved in the initial interaction with the membrane surface. Modelling the interaction of nisin with different neutral or anionic phospholipids shows that it disturbs the lipid organisation. The disturbance is maximal with phosphatidylglycerol. In this system, nisin curves the surface of phosphatidylglycerol layer round suggesting it could induce micelle formation. This could be a preliminary step to pore formation. It suggests that phosphatidylglycerol could have a direct action on nisin insertion and on ion channel formation. Appearance of a curvature also agrees with the 'wedge model' proposed in the literature for the nisin pore formation. [less ▲]

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See detailComputational study of the error distribution in right-censored and selection-biased regression models
Laurent, Géraldine ULg; Heuchenne, Cédric ULg

Conference (2010, May 18)

Consider the regression model Y = m(X) + σ(X) Ɛ where m(X) =E [Y|X] and σ²(X) = Var [Y|X] are unknown smooth functions and the error Ɛ, with unknown distribution, is independent of X. The pair (X,Y) is ... [more ▼]

Consider the regression model Y = m(X) + σ(X) Ɛ where m(X) =E [Y|X] and σ²(X) = Var [Y|X] are unknown smooth functions and the error Ɛ, with unknown distribution, is independent of X. The pair (X,Y) is subject to generalized selection bias and the response to right censoring. We construct a new estimator for the cumulative distribution function of the error Ɛ, and develop a bootstrap technique to select the smoothing parameter involved in the procedure. The estimator is studied via extended simulations and applied to real unemployment data. [less ▲]

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See detailComputational toxicology: Physiologically based pharmacokinetic models (PBPK) for lifetime exposure and bioaccumulation of polybrominated dephenyl ethers (PBDEs) in marine mammals
Weijs, Liesbeth; Covaci, Adrian; Yang, Raymond S H et al

in Environmental Pollution (2012)

Due to migration of harbour porpoises towards more polluted areas like the North Sea and their sensitivity towards pollution, there is a need for proper conservation measures for this species. As a ... [more ▼]

Due to migration of harbour porpoises towards more polluted areas like the North Sea and their sensitivity towards pollution, there is a need for proper conservation measures for this species. As a consequence, knowledge about the pollutant’s kinetics is required. The present study is the first to investigate the kinetics of PBDEs in marine mammals using PBPK modeling as a non-destructive tool for describing the chemical’s kinetics in a protected animal species. The models were developed and parameterized using data from the literature and Black Sea harbour porpoises through computer opti- mization. The predictability of these models in time was assessed by reverse dosimetry modeling using data from North Sea porpoises (1990e2008). From these predictions, PBDE 99 levels were found to decrease the fastest, followed by PBDE 153, 47 and 100. Results show that the PBPK models can be applied for harbour porpoises from different regions and also simulate time trends. [less ▲]

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See detailComputational treatment of the error distribution in nonparametric regression with right-censored and selection-biased data
Laurent, Géraldine ULg; Heuchenne, Cédric ULg

Conference (2010, August 24)

Consider the regression model Y = m(X) + σ(X) Ɛ , where m(X) = E[Y|X] and σ²(X) = Var[Y|X] are unknown smooth functions and the error Ɛ (with unknown distribution) is independent of X. The pair (X;Y) is ... [more ▼]

Consider the regression model Y = m(X) + σ(X) Ɛ , where m(X) = E[Y|X] and σ²(X) = Var[Y|X] are unknown smooth functions and the error Ɛ (with unknown distribution) is independent of X. The pair (X;Y) is subject to generalized selection bias and the response to right censoring. We construct a new estimator for the cumulative distribution function of the error Ɛ , and develop a bootstrap technique to select the smoothing parameter involved in the procedure. The estimator is studied via extended simulations and applied to real unemployment data. [less ▲]

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See detailComputational treatment of the error distribution in nonparametric regression with right-censored and selection-biased data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

in Proceedings of the 19th International Conference on Computational Statistics (2010)

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See detailComputational, Structural, and Mechanistic Analysis of the Electrochemically Driven Pirouetting Motion of a Copper Rotaxane
Periyasamy, Ganga ULg; Sour, A.; Collin, Jacques ULg et al

in Journal of Physical Chemistry B (2009), 113(18), 6219-6229

A mechanism for the electrochemically driven reorganization of a model copper [2]pseudorotaxane is proposed on the basis of density functional theory computations and validated by comparing to ... [more ▼]

A mechanism for the electrochemically driven reorganization of a model copper [2]pseudorotaxane is proposed on the basis of density functional theory computations and validated by comparing to experimental results. We investigate in detail the ligand reorganization around the Cu ion from a 4 to 5 coordination number that follows the conversion of the oxidation state from +1 to +2. It is found that for both the oxidation and the reduction processes the rearrangement proceeds in a concerted fashion via a single transition state. Energy paths involving stable decoordinated-coordinated intermediates are computed to be higher in energy. The cyclic voltammogram simulated using the computed transition theory state rate constants in solvent medium is in good agreement with the experimental voltammogram. Further, we report on the computed concentration change of stable (Cu-4(+), Cu-5(2+)) and metastable species (Cu-4(2+), Cu-5(+)) during single cyclic voltammetry (CV) cycle as a function of the applied voltage or time (the subscripts 4 and 5 refer to the coordination number of the copper center). [less ▲]

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See detailA computationally efficient algorithm for the provision of a day-ahead modulation service by a load aggregator
Mathieu, Sébastien ULg; Karangelos, Efthymios ULg; Louveaux, Quentin ULg et al

Poster (2012, October 08)

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service ... [more ▼]

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service consisting of a load modulation option, which can be called by the TSO once per day. The option specifies the maximum amplitude of a potential modification on the demand of the loads within a certain time interval. We consider the specific case where the loads can be modeled by a generic tank model whose inflow depends on the power consumed by the load and outflow is assumed to be known the day before for every market period. The level of the reservoir at the beginning of the market day is also assumed to be known. We show that, under these assumptions, the problem of maximizing the amplitude of the load modulation service can be formulated as a mixed integer linear programming problem (MILP). In order to solve this problem in a computationally efficient manner we introduce a novel heuristic-method. We test this method on a set of problems and demonstrate that our approach is orders of magnitude faster than CPLEX - a state-of-the-art software for solving MILP problems - without considerably compromising the solution accuracy. [less ▲]

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See detailA computationally efficient hybrid leakage model for positive displacement compressors and expanders
Bell, Ian ULg; Groll, Eckhard; Braun, James E. et al

in International Journal of Refrigeration (2013), 36

An empirical frictional correction factor to the isentropic nozzle model has been developed for application to refrigerant leakage modeling in scroll, rotary and other similar compressors. This correction ... [more ▼]

An empirical frictional correction factor to the isentropic nozzle model has been developed for application to refrigerant leakage modeling in scroll, rotary and other similar compressors. This correction factor is derived by calculating the leakage mass flow rate with a compressible, variable area, real gas properties model and referencing the results to an isentropic nozzle model. The ratio of flows is correlated to the Reynolds number, a characteristic length and the leakage gap width. A representative selection of fluids and geometries are employed. For all the correlations, at least 93% of the points are predicted within an absolute error band of 20%. [less ▲]

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See detailComputationally-efficient Range-dependence Compensation Method for Bistatic Radar STAP
Lapierre, Fabian D.; Ries, Philippe; Verly, Jacques ULg

Conference (2005)

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See detailComputed subsidence of the central area of Shanghai
Dassargues, Alain ULg; Radu, Jean-Pol ULg; Charlier, Robert ULg et al

in Bulletin of Engineering Geology & the Environment (1993), 47

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See detailComputed Tomographic Features of Choanal Atresia in a Friesian Foal
Van Galen, Gaby ULg; Bolen, Géraldine ULg; Verwilghen, Denis ULg et al

in Journal of Equine Veterinary Science (2010), 30(8), 436-440

A 3 week old Friesian foal colt was presented with a history of respiratory distress since birth. Endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography (CT) was ... [more ▼]

A 3 week old Friesian foal colt was presented with a history of respiratory distress since birth. Endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography (CT) was performed to further characterize this unilateral blockage: images showed demonstrated a complete membranous obstruction of the ventral meatus, together with a deviation of the vomer bone to the left. The diagnosis of unilateral choanal atresia was confirmed. This is the first report describing CT features of choanal atresia in a foal. [less ▲]

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See detailComputed tomographic findings in 35 dogs with nasal aspergillosis
Saunders, J. H.; Zonderland, J. L.; Clercx, Cécile ULg et al

in Veterinary Radiology & Ultrasound (2002), 43(1, JAN-FEB), 5-9

The purpose of this study was to describe the computed tomographic (CT) features of nasal aspergillosis in dogs. Initial (n = 35) and follow-up (n = 12) CT images were available from 35 dogs. The most ... [more ▼]

The purpose of this study was to describe the computed tomographic (CT) features of nasal aspergillosis in dogs. Initial (n = 35) and follow-up (n = 12) CT images were available from 35 dogs. The most commonly encountered CT findings were (1) moderate to severe cavitary destruction of the turbinates with presence of a variable amount of abnormal soft tissue in the nasal passages, (2) non-specific thickening of the mucosa adjacent to the inner surface of bones of the frontal sinus, maxillary recess and nasal cavity and, (3) thickened reactive bone. The findings were consistent with a disease initially affecting one nasal cavity then progressing into the ipsilateral frontal sinus, the contralateral nasal cavity and the contralateral frontal sinus. Two dogs with associated nasal foreign body had a more localized invasion of the nasal cavity. Attenuation values and contrast enhancement were not specific. With follow-up examinations, a reduction in the amount of abnormal soft tissue was observed in all dogs except one, but this reduction could not be quantified. [less ▲]

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See detailComputed tomographic pulmonary angiography and prognostic significance in patients with acute pulmonary embolism
Ghuysen, Alexandre ULg; Ghaye, Benoît ULg; Willems, V. et al

in Thorax (2005), 60(11), 956-961

Background: Patients with acute pulmonary embolism (APE) present with a broad spectrum of prognoses. Computed tomographic pulmonary angiography (CTPA) has progressively been established as a first line ... [more ▼]

Background: Patients with acute pulmonary embolism (APE) present with a broad spectrum of prognoses. Computed tomographic pulmonary angiography (CTPA) has progressively been established as a first line test in the APE diagnostic algorithm, but estimation of short term prognosis by this method remains to be explored. Methods: Eighty two patients admitted with APE were divided into three groups according to their clinical presentation: pulmonary infarction (n=21), prominent dyspnoea (n=29), and circulatory failure (n=32). CTPA studies included assessment of both pulmonary obstruction index and right heart overload. Haemodynamic evaluation was based on systolic aortic blood pressure, heart rate, and systolic pulmonary arterial pressure obtained non-invasively by echocardiography at the time of diagnosis of pulmonary embolism. Results: The mortality rate was 0%, 13.8% and 25% in the three groups, respectively. Neither the pulmonary obstruction index nor the pulmonary artery pressure could predict patient outcome. In contrast, a significant correlation with mortality was found using the systolic blood pressure (p<0.001) and heart rate (p<0.05), as well as from imaging parameters including right to left ventricle minor axis ratio (p<0.005), proximal superior vena cava diameter (p<0.001), azygos vein diameter (p<0.001), and presence of contrast regurgitation into the inferior vena cava (p=0.001). Analysis from logistic regression aimed at testing for mortality prediction revealed true reclassification of 89% using radiological variables. Conclusion: These results suggest that CTPA quantification of right ventricular strain is an accurate predictor of in-hospital death related to pulmonary embolism. [less ▲]

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See detailComputed tomography anatomy of the equine metacarpo-phalangeal joint
Vanderperren; Ghaye, Benoit ULg; Hoegaerts, Michel et al

Poster (2007)

Detailed reference viewed: 7 (1 ULg)