Search results for " Modeling"
showing 10 items of 2411 documents
Vertical distribution of AhR-activating compounds in sediments contaminated by modernized pulp and paper industry
2013
Increased ethoxyresorufin-O-deethylase (EROD) activity is a sensitive biomarker of exposure to the chemicals which activate the aryl hydrocarbon receptor (AhR) and induce the cytochrome P450 system, such as many polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). Pulp bleaching was one of the main sources of PCDDs and PCDFs until elemental chlorine free (ECF) and total chlorine free bleaching processes since 1990s have remarkably decreased but not completely eliminate discharges of these chemicals. In addition, historically contaminated sediments may act as a source of these persistent contaminants. In this study, the contam…
IDEA: interface dynamics and energetics algorithm.
2007
IDEA, interface dynamics and energetics algorithm, was implemented, in FORTRAN, under different operating systems to mimic dynamics and energetics of elementary events involved in interfacial processes. The code included a parallel elaboration scheme in which both the stochastic and the deterministic components, involved in the developed physical model, worked simultaneously. IDEA also embodied an optionally running VISUAL subroutine, showing the dynamic energy changes caused by the surface events, e.g., occurring at the gas-solid interface. Monte Carlo and ordinary differential equation system subroutines were employed in a synergistic way to drive the occurrence of the elementary events a…
Design and Digital Fabrication of a Parametric Joint for Bamboo Sustainable Structures
2019
The study deepens the design of a joining system for bamboo spatial structure by proposing new and advanced solutions that guarantee maximum freedom of composition to the designer. The joint allows to determine and control parametrically the adaptability to any spatial grid configuration of culms with heterogeneous dimensions. Despite the bamboo being one of the main natural building materials in the field of sustainable architecture, currently, it is not used enough due to the lack of adequate connection systems. Bamboo is a rapidly growing renewable resource, naturally available, which is quite strong and lends itself to structural applications. The paper proposes an innovative approach t…
Fitting particle size distribution models to data from Burundian soils for the BEST procedure and other purposes
2009
Testing the Beerkan Estimation of Soil Transfer (BEST) soil particle size distribution (PSD) model is necessary to evaluate the applicability of the BEST procedure for characterising soil hydraulics. In this investigation, the fitting performance of the BEST PSD model was tested using a database of 114 Burundian soils with 14 measured particle size fractions for each soil sample, and also by considering a reduced number of measured particle size fractions for a sample. The fitting performance of the model developed by Fredlund et al. (2000) (FR model) was also considered for comparative purposes. On average, the BEST model yielded satisfactory results (i.e., mean relative error, E r ¯ = 3.9…
Acquired IFNγ resistance impairs anti-tumor immunity and gives rise to T-cell-resistant melanoma lesions
2016
Melanoma treatment has been revolutionized by antibody-based immunotherapies. IFNγ secretion by CD8+ T cells is critical for therapy efficacy having anti-proliferative and pro-apoptotic effects on tumour cells. Our study demonstrates a genetic evolution of IFNγ resistance in different melanoma patient models. Chromosomal alterations and subsequent inactivating mutations in genes of the IFNγ signalling cascade, most often JAK1 or JAK2, protect melanoma cells from anti-tumour IFNγ activity. JAK1/2 mutants further evolve into T-cell-resistant HLA class I-negative lesions with genes involved in antigen presentation silenced and no longer inducible by IFNγ. Allelic JAK1/2 losses predisposing to …
Patient-specific simulation of the intrastromal ring segment implantation in corneas with keratoconus
2015
Purpose The purpose of this study was the simulation of the implantation of intrastromal corneal-ring segments for patients with keratoconus. The aim of the study was the prediction of the corneal curvature recovery after this intervention. Methods Seven patients with keratoconus diagnosed and treated by implantation of intrastromal corneal-ring segments were enrolled in the study. The 3D geometry of the cornea of each patient was obtained from its specific topography and a hyperelastic model was assumed to characterize its mechanical behavior. To simulate the intervention, the intrastromal corneal-ring segments were modeled and placed at the same location at which they were placed in the s…
Victimization at school: relationship of parenting and functional-dysfunctional developmental variables
2015
El presente estudio tiene como principal objetivo analizar elpapel diferencial de la crianza (apoyo y comunicación versus control), devariables funcionales del desarrollo (empatía y mecanismos de afrontamientofuncionales) y las variables disfuncionales (inestabilidad emocional yafrontamiento improductivo) en la victimización ocurrida en el entorno escolar,o por el contrario, con el apego entre pares. Participaron en el estudio418 alumnos, 224 chicas y 194 chicos adolescentes, entre 13 y 14 años,escolarizados en los niveles de 3º y 4º curso de Educación SecundariaObligatoria. Para analizar estas relaciones se llevó a cabo un modelo deecuaciones estructurales EQS. Los resultados obtenidos mue…
Adaptation and Psychometric Properties of the Scale of Positive and Negative Experience (SPANE) in the General Colombian Population
2021
(1) Background: Diener’s Scale of Positive and Negative Experiences (SPANE) assesses the presence and intensity of positive and negative affects, since these are considered basic aspects of the study of well-being. This article studies its psychometric properties in the general Colombian population. (2) We conducted a cross-sectional study of a sample of 1255 Colombians and we used structural equation modeling to confirm the bifactor structure. Additionally, we studied invariance by gender, and convergent and concurrent validity. (3) We found acceptable fit indicators for the bifactor model (CFI = 0.889, RMSEA = 0.046, SRMR = 0.059) as well as for the convergent (CFI = 0.909, RMSEA = 0.050,…
Performance status and depressive symptoms as predictors of quality of life in cancer patients. A structural equation modeling analysis
2015
Objective: This study aimed to examine whether depressive symptoms and performance status are independent predictors of both the physical and psychological domains of health-related quality of life (HRQoL) in cancer patients. Methods: A sample of 4020 cancer patients (mean age 58 years, 51% women) was evaluated. Depressive symptoms were measured with the patient health questionnaire and HRQoL with the European Organisation for Research and Treatment of Cancer quality of life questionnaire core 30. The impact of the illness on everyday activities was assessed with physician ratings of both the Karnofsky performance status and the Eastern Cooperative Oncology Group performance status. The sim…
Modelling anaerobic biomass growth kinetics with a substrate threshold concentration.
2004
Abstract Many bacteria have been observed to stop growing below a certain substrate threshold concentration. In this study, a modification of the Monod kinetics expression has been proposed to take into account this substrate threshold concentration observed in bacterial growth. Besides the threshold concentration no additional parameters have been added to the kinetic expression and so, only the substrate threshold concentration and the half-saturation constant have to be estimated for model calibration purposes. Furthermore, for parameter estimation purposes, practical identifiability of this new function has been studied and the results have been satisfactory. The new model has been appl…