Search results for "quantitative"
showing 10 items of 2409 documents
Uncertainty quantification on a spatial Markov-chain model for the progression of skin cancer
2019
AbstractA spatial Markov-chain model is formulated for the progression of skin cancer. The model is based on the division of the computational domain into nodal points, that can be in a binary state: either in ‘cancer state’ or in ‘non-cancer state’. The model assigns probabilities for the non-reversible transition from ‘non-cancer’ state to the ‘cancer state’ that depend on the states of the neighbouring nodes. The likelihood of transition further depends on the life burden intensity of the UV-rays that the skin is exposed to. The probabilistic nature of the process and the uncertainty in the input data is assessed by the use of Monte Carlo simulations. A good fit between experiments on mi…
From Feynman–Kac formulae to numerical stochastic homogenization in electrical impedance tomography
2016
In this paper, we use the theory of symmetric Dirichlet forms to derive Feynman–Kac formulae for the forward problem of electrical impedance tomography with possibly anisotropic, merely measurable conductivities corresponding to different electrode models on bounded Lipschitz domains. Subsequently, we employ these Feynman–Kac formulae to rigorously justify stochastic homogenization in the case of a stochastic boundary value problem arising from an inverse anomaly detection problem. Motivated by this theoretical result, we prove an estimate for the speed of convergence of the projected mean-square displacement of the underlying process which may serve as the theoretical foundation for the de…
Formulations and exact algorithms for the distance-constrained generalized directed rural postman problem
2017
[EN] The generalized directed rural postman problem is an arc routing problem with many interesting real-life applications, such as routing for meter reading. In this application, a vehicle with a receiver travels through a series of neighborhoods. If the vehicle gets closer than a certain distance to a meter, the receiver is able to record the gas, water, or electricity consumption. Therefore, the vehicle does not need to traverse every street, but only a few, to get close enough to each meter. We study an extension of this problem in which a fleet of vehicles is available. Given the characteristics of the mentioned application, the vehicles have no capacities but there is a maximum distan…
Fremmede arter i Norge: resultater fra kvantitative økologiske risikovurderinger
2020
1. Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2. We risk-assessed all alien plants, animals, fungi and algae, within certain delimitations, that are known to reproduce in Norway. Mainland Norway and the Arctic archipelago of Svalbard plus Jan Mayen were treated as separate assessment areas. Assessments followed the Generic Ecological Impact Assessment of Alien Species (GEIAA) protocol, which uses a fully quantitative set of criteria.…
Development and application of Bayesian dynamic compartment modelling to study labour (in)stability in Spain
2022
Esta es una tesis metodológica en la que nos centramos en el mercado laboral. Sin embargo, los métodos aquí desarrollados también podrían aplicarse a otras áreas de las Ciencias Sociales permitiendo a los/las investigadores/investigadoras ampliar el conocimiento al abordar las preguntas de investigación desde un punto de vista diferente. En este contexto, la (in)estabilidad laboral podría entenderse como la velocidad de transición del empleo al no empleo y viceversa. Si la velocidad es alta, la inestabilidad también es alta; por el contrario, si la velocidad de transición es baja, habrá una baja inestabilidad. El objetivo principal de esta tesis es desarrollar un nuevo marco metodológico pa…
Polyoxypregnanes as safe, potent, and specific ABCB1-inhibitory pro-drugs to overcome multidrug resistance in cancer chemotherapy in vitro and in vivo
2021
Multidrug resistance (MDR) mediated by ATP binding cassette subfamily B member 1 (ABCB1) is significantly hindering effective cancer chemotherapy. However, currently, no ABCB1-inhibitory drugs have been approved to treat MDR cancer clinically, mainly due to the inhibitor specificity, toxicity, and drug interactions. Here, we reported that three polyoxypregnanes (POPs) as the most abundant constituents of Marsdenia tenacissima (M. tenacissima) were novel ABCB1-modulatory pro-drugs, which underwent intestinal microbiota-mediated biotransformation in vivo to generate active metabolites. The metabolites at non-toxic concentrations restored chemosensitivity in ABCB1-overexpressing cancer cells v…
Creatinine determination in urine samples by batchwise kinetic procedure and flow injection analysis using the Jaffé reaction: chemometric study
2001
The classical Jaffé reaction for the determination of creatinine in urine samples is tested. A comparative study of the main analytical characteristics focussed to minimize the bias error and improve the precision, for the batchwise and flow injection (FI) methods is realized. Also, the effect of the albumin concentration in the determination of creatinine has been studied. Different analytical signals were studied. Absorbance increments at different times permit to estimate the creatinine concentration free from bias error in urine by the batchwise method using the calibration graph obtained with creatinine standards and no measurement of the blank solution is needed. The lineal interval w…
PLS-UV spectrophotometric method for the simultaneous determination of paracetamol, acetylsalicylic acid and caffeine in pharmaceutical formulations
1997
A simple and fast analytical procedure is proposed for the simultaneous determination of paracetamol, acetylsalicylic acid and caffeine in pharmaceuticals by means the partial least square treatment of the spectrophotometric absorbance data between 216 and 300 nm, taken at 5 nm intervals. The method involves the use of 8 standard mixtures of the three compounds assayed, considered at two concentration levels, and the measurement of the absorbance of samples in a 20% (v/v) ethanol in water solution previously filtered. In the analysis of real and synthetic samples precise and accurate values were obtained by the aforementioned procedure, providing in all cases variation coefficients and accu…
Quantitative analysis of the effect of controlled-release formulation on nonlinear gastrointestinal absorption of P-glycoprotein substrate talinolol …
2020
Abstract Oral absorption of talinolol, a substrate of P-glycoprotein (P-gp), from a sustained-release (SR) formulation was reportedly decreased compared to that from an immediate-release (IR) formulation. The aim of this study was to predict and understand the effect of controlled-release formulation on the oral absorption of P-gp substrates by developing a physiologically based pharmacokinetic (PBPK) absorption model incorporating multiple kinetic parameters obtained from in vitro studies, using talinolol as a model substrate. Simulation analysis using the developed PBPK absorption model indicated that the clinically observed marked decrease in the plasma concentration of talinolol adminis…
Estimation of ADME Properties in Drug Discovery: Predicting Caco-2 Cell Permeability Using Atom-Based Stochastic and Non-stochastic Linear Indices
2007
The in vitro determination of the permeability through cultured Caco-2 cells is the most often-used in vitro model for drug absorption. In this report, we use the largest data set of measured P(Caco-2), consisting of 157 structurally diverse compounds. Linear discriminant analysis (LDA) was used to obtain quantitative models that discriminate higher absorption compounds from those with moderate-poorer absorption. The best LDA model has an accuracy of 90.58% and 84.21% for training and test set. The percentage of good correlation, in the virtual screening of 241 drugs with the reported values of the percentage of human intestinal absorption (HIA), was greater than 81%. In addition, multiple …