Search results for "Lability"
showing 10 items of 802 documents
Controllability method for the Helmholtz equation with higher-order discretizations
2007
We consider a controllability technique for the numerical solution of the Helmholtz equation. The original time-harmonic equation is represented as an exact controllability problem for the time-dependent wave equation. This problem is then formulated as a least-squares optimization problem, which is solved by the conjugate gradient method. Such an approach was first suggested and developed in the 1990s by French researchers and we introduce some improvements to its practical realization. We use higher-order spectral elements for spatial discretization, which leads to high accuracy and lumped mass matrices. Higher-order approximation reduces the pollution effect associated with finite elemen…
Time-harmonic elasticity with controllability and higher-order discretization methods
2008
The time-harmonic solution of the linear elastic wave equation is needed for a variety of applications. The typical procedure for solving the time-harmonic elastic wave equation leads to difficulties solving large-scale indefinite linear systems. To avoid these difficulties, we consider the original time dependent equation with a method based on an exact controllability formulation. The main idea of this approach is to find initial conditions such that after one time-period, the solution and its time derivative coincide with the initial conditions.The wave equation is discretized in the space domain with spectral elements. The degrees of freedom associated with the basis functions are situa…
High-quality computational tools for linear-algebra problems in FEM electromagnetic simulation [EM Programmer's Notebook]
2004
A key ingredient of finite-element analysis programs is the linear-algebra solver, typically either a linear-system solver or an eigensolver. The first part of This work tries to justify why it is important to have recourse to publicly available software for addressing this part of the computation. A number of libraries are mentioned as successful examples that exhibit a series of desirable qualities. Although some of these libraries force the programmer to somewhat change the programming style and may be difficult to learn, the benefits usually pay off the extra effort. The second part of the paper describes one of these libraries in some detail, namely SLEPc, the Scalable Library for Eige…
Impact of HPP on the bioaccessibility/bioavailability of nutrients and bioactive compounds as a key factor in the development of food processing
2020
Abstract High-pressure processing (HPP) technology has great potential for manipulating the structure and functionality of the components present in food matrices, therefore considerably affecting their bioaccessibility and bioavailability. Without knowledge of the principles and mechanisms responsible for these modifications, this technology’s potential is still not fully understood and justified from a nutritional point of view. This chapter presents the results of some of the main studies carried out to date to assess the impact of HPP on the bioaccessibility and bioavailability of nutrients and bioactive compounds of different food matrices.
Bioavailability of zinc from infant foods byin vitro methods (solubility, dialyzability and uptake and transport by Caco-2 cells)
2006
The aim of this study was to evaluate the bioavailability of zinc from infant foods (adapted, follow-up and toddler milk-based formulas and fruit juices containing milk and cereals, FMC) using solubility, dialyzability and a model combining simulated gastrointestinal digestion and zinc uptake and transport by Caco-2 cells. The greater solubility of zinc from infant formulas compared with fruit juices (FMC) could be due to the greater casein phosphopeptide content resulting from casein hydrolysis. The highest zinc dialysis percentage corresponded to FMC, which on the other hand had the lowest zinc contents of the analyzed samples. The presence of organic acids in samples of this kind favors …
Bioavailability of plant sterol-enriched milk-based fruit beverages: In vivo and in vitro studies
2015
Abstract This study for the first time compares the in vivo (response in serum from individuals of an interventional study) and in vitro effects (bioaccessibility determined from simulated gastrointestinal digestion) of two plant sterol (PS)-enriched milk-based fruit beverages (with and without tangerine fruit juice rich in β-cryptoxanthin (β-Cx)) in order to assess their suitability as PS-enriched food matrixes, and the possible interactions between the two bioactive compounds (β-Cx and PS) that might affect their absorption. The randomized, double-blind, crossover study (performed in 36 postmenopausal women) showed the β-sitosterol and campesterol serum concentrations after four weeks of …
Effects of legume processing on calcium, iron and zinc contents and dialysabilities
2001
Legumes are a good source of calcium, iron and zinc, but are also a source of phytates and dietary fibre components that can negatively affect the bioavailability of these minerals. To estimate the latter, an in vitro dialysis method can be applied that gives the dialysability of a mineral as an estimate of its availability for absorption. Calcium, iron and zinc contents and dialysabilities in three legumes (beans, chickpeas and lentils) and the effects of cooking treatments and industrial processing on these parameters were studied. Beans had the highest calcium content (1.54 g kg -1 dry matter (DM)) and chickpeas the lowest iron content (46.9mg kg -1 DM), whilst the zinc contents were sim…
Population pharmacokinetic model of lithium and drug compliance assessment.
2016
Population pharmacokinetic analysis of lithium during therapeutic drug monitoring and drug compliance assessment was performed in 54 patients and 246 plasma concentrations levels were included in this study. Patients received several treatment cycles (1-9) and one plasma concentration measurement for each patient was obtained always before starting next cycle (pre-dose) at steady state. Data were analysed using the population approach with NONMEM version 7.2. Lithium measurements were described using a two-compartment model (CL/F=0.41Lh-1, V1/F=15.3L, Q/F=0.61Lh-1, and V2/F = 15.8L) and the most significant covariate on lithium CL was found to be creatinine clearance (reference model). Lith…
Impact of body weight, low energy diet and gastric bypass on drug bioavailability, cardiovascular risk factors and metabolic biomarkers: protocol for…
2018
IntroductionRoux-en-Y gastric bypass (GBP) is associated with changes in cardiometabolic risk factors and bioavailability of drugs, but whether these changes are induced by calorie restriction, the weight loss or surgery per se, remains uncertain. The COCKTAIL study was designed to disentangle the short-term (6 weeks) metabolic and pharmacokinetic effects of GBP and a very low energy diet (VLED) by inducing a similar weight loss in the two groups.Methods and analysisThis open, non-randomised, three-armed, single-centre study is performed at a tertiary care centre in Norway. It aims to compare the short-term (6 weeks) and long-term (2 years) effects of GBP and VLED on, first, bioavailability…
Clinical Applications, Pitfalls, and Uncertainties of Thrombin Generation in the Presence of Platelets
2019
Platelet-dependent thrombin generation is a helpful tool to assess ex vivo the interaction between platelets and plasma coagulation factors in the initiation, amplification, and inhibition of thrombin generation (TG). This review article discusses the most relevant available data on the clinical applications of fluorogenic TG, the most widely used TG assay, performed in the presence of platelets, i.e., in platelet-rich plasma. With respect to prothrombotic states, arterial hypertension and obesity were the most prominent cardiovascular conditions linked to increased platelet-dependent TG. In addition, platelet-associated hypercoagulability, assessed by the TG assay, has been shown in indivi…