Search results for "Modelling"

The effect of physical education students' beliefs and values on their physical activity: A growth mixture modelling approach

2013

This study examined the change in adolescents' expectancy-related beliefs and task values towards physical education (PE). In addition, the physical activity (PA) growth trajectories of the identified adolescent subpopulations were examined. This study comprised 812 students (age M = 12.31, range: 11–13), who answered questionnaires four times during Grades 6–9. This study found that expectancy-related beliefs declined, while task values increased across the middle school transition. Adolescents who valued PE highly and experienced an increase in their expectancy-related beliefs became physically more active across time, while adolescents with the lowest levels and the most negative change …

Trajectories of depressive symptoms during emerging adulthood: Antecedents and consequences

2008

In order to examine what kinds of trajectories of depressive symptoms young adults show during emerging adulthood, and their antecedents and consequences, 297 university students completed the revised Beck's depression inventory seven times over a 10-year period, and other measures at the beginning and the end of the study. The growth mixture modelling for depressive symptoms ended up in a 3-group solution: 23% of the participants were typified by a low level of symptoms, 61% showed a moderate level, and 16% fell into the third group with high and increasing levels of depressive symptoms during emerging adulthood. Those on the high-depressive trajectory had a poorer quality of relationships…

Using random networks to study the dynamics of respiratory syncytial virus (RSV) in the Spanish region of Valencia

2011

[EN] Seasonal fluctuations in the incidence of several respiratory infections are a feature of epidemiological surveys all around the world. This phenomenon is characteristic of influenza and respiratory syncytial virus pandemics. However, the explanation of the seasonal outbreaks of these diseases remains poorly understood. Many statistical studies have been carried out in order to provide a correlation of the outbreaks with climatic or social factors without achieving a definitive conclusion. Here we show that, in a random social network, self-sustained seasonal epidemics emerge as a process modulated by the infection probability and the immunity period after recovering from the infection…

Mechanisms for Translocation of Heavy Metals from Soil to Epigeal Mosses

2011

The mechanisms for translocation of heavy metals from soil to epigeal mosses were investigated. The first mechanism was demonstrated for (137)Cs and involved the uplifting of the pollutant-containing dust from the soil, followed by the local secondary deposition on surfaces of epigeal mosses and epiphytic lichens. The second mechanism involved the diffusion of metal cations from the soil through water wetting the moss into the gametophyte. The mechanism was demonstrated by measuring the electric conductance of wetted gametophytes with single ends immersed in solutions of Cu and Na salts. In addition, the concentrations of Cu and Cd were compared in moss samples exposed to the natural soil a…

Advances in Laboratory Testing and Modelling of Soils and Shales (ATMSS).

2017

This volume contains the invited keynote and feature lectures, as well as the papers that have been presented at the workshop. The topics of the lectures and papers cover a wide range of theoretical and experimental research, including unsaturated behaviour of soils and shales, multiphysical testing of geomaterials, hydromechanical behaviour of shales and stiff clays, the geomechanical behaviour of the Opalinus Clay shale, advanced laboratory testing for site characterization and in situ applications, and soil–structure interactions.

4D paleoenvironmental evolution of the Early Triassic Sonoma Foreland Basin (western USA)

2017

In the wake of the Mesozoic, the Early Triassic (~251.95 Ma) corresponds to the aftermath of the most severe mass extinction of the Phanerozoic: the end-Permian crisis, when life was nearly obliterated (e.g., 90% of marine species disappeared). Consequences of this mass extinction are thought to have prevailed for several millions of years, implying a delayed recovery lasting the whole Early Triassic, if not more. Several paradigms have been established and associated to a delayed biotic recovery scenario expected to have resulted from harsh and deleterious paleoenvironments. These paradigms include a global anoxia in the marine realm, a “Lilliput” effect, and the presence of “disaster” tax…

Modelling of Pulsed Electro Acoustic Method for Space Charge Detection on Single and Multilayer Dielectrics

Probabilité d'apparition d'un phénomène parasitaire et choix de modèles de régression logistique

2007

Epidemiological processes are now using spatial statistics and modelling tools. The main objective of most health risks studies consists in identifying potential contamination sources and factors capable of explaining their localization. Health data often prove binary (typically presence/absence) and specific methods such as binary logistic regression have to be used. This method's output consists in a probability for the pathogen of interest. A posterior classification of each sample is then conducted using a probability threshold. The method used to maximize this threshold is called the ROC curve which consists in giving a representation of the behaviour of the model and then to choose th…

Residential satisfaction and spatial configurations in a periurban area

2011

Since the 1960s, French cities are concerned with an urban sprawl process. This urban sprawl leads to the emergence of a particular space located at the interface between the city and the countryside: the periurban. The social, morphological or the spatial practices of its inhabitants give the suburban a particular singularity and specificity. It is a space of contradiction that attracts both because of the "natural" living environment that it provides to households, but also because of its proximity to the city and the opportunities related to accessibility to various urban amenities.To understand more precisely this enthusiasm for periurban areas, this thesis proposes to explore the indiv…

Linear stability analysis of gas-fluidized beds for the prediction of incipient bubbling conditions

2010

Abstract This work focuses on the development of a novel linear stability criterion for the state of homogeneous fluidization regime, based on a new mathematical model for gas-fluidized beds. The model is developed starting from the well-known particle bed model. A mono-dimensional momentum balance is derived leading to a set of equations which explicitly include voidage-gradient dependent terms (elastic force) for both solid and fluid phases. A fully predictive criterion for the stability of homogeneous fluidization state is here proposed, based on the well-known Wallis’ linear stability analysis. The criterion requires the choice of an appropriate averaging distance, which in the present …