Alien Registration- Julien, Rose A. (Jackman, Somerset County)

https://digitalmaine.com/alien_docs/6994/thumbnail.jp

Sympatric Dreissena species in the Meuse River : towards a dominance shift from zebra to quagga mussels

The rapid spread of the quagga mussel, Dreissena rostriformis, in Western Europe is of particular concern since the species is known to have serious ecological and economic impacts, similar to those of the well-established zebra mussel, Dreissena polymorpha. This study aimed (1) to provide an update on the quagga mussel distribution in several Belgian inland waterways, and (2) to check if a shift in dominance between Dreissena species is occurring. Using density measurements and artificial substrate samplers, we compared population dynamics for both species at different time-points based on size-frequency distribution. Our results show that quagga mussels are spreading rapidly throughout Belgium via a number of possible invasion fronts based around large rivers and canals. The quagga mussel became the dominant dreissenid species in both the Meuse River and a number of Belgian canals. In just three years, quagga mussel’s relative abundance increased from 2.9% (±2.9) to 52.6% (±43.1) of the total dreissenid population in the Meuse River. The most rapid increase in abundance has occurred in the Albert Canal, where quagga mussels achieved a mean relative abundance of 80% two years after the first observation. In the Meuse River, the quagga mussel displays a faster growth rate and/or earlier reproduction than the zebra mussel. We discuss different mechanisms that could explain the quagga mussel’s apparent competitive advantage over the zebra mussel

A Multi-HMM Approach to ECG Segmentation

ISSN: 1082-3409International audiencePharmaceutic studies require to analyze thousands of ECGs in order to evaluate the side effects of a new drug. In this paper we present a new approach to automatic ECG segmentation based on hierarchic continuous density hidden Markov models. We applied a wavelet transform to the signals in order to highlight the discontinuities in the modeled ECGs. A training base of standard 12-lead ECGs segmented by cardiologists was used to evaluate the performance of our method. We used a Bayesian HMM clustering algorithm to partition the training base, and we improved the method by using a multi-model approach. We present a statistical analysis of the results where we compare different automatic methods to the segmentation of the cardiologist

A Support System for ECG Segmentation Based on Hidden Markov Models

Scheduled for presentation during the Poster Session "Signal Pattern Classification in Biomedical Signals V" (FrP2A1)International audiencePharmaceutic studies require to analyze thousands of ECGs in order to evaluate the side effects of a new drug. In this paper we present a new support system based on the use of probabilistic models for automatic ECG segmentation. We used a bayesian HMM clustering algorithm to partition the training base, and we improved the method by using a multi-channel segmentation. We present a statistical analysis of the results where we compare different automatic methods to the segmentation of the cardiologist as a gold standard

Valeurs propres de solutions analytiques et de problèmes de transmission dans des milieux poroélastiques isotropes pour des domaines bornés, pour la diffraction d’obstacles et pour des intéractions fluide-solide en 2D

In this report, we construct analytical solutions and study numerically the well-posedness of several problems concerning the isotropic poroelastic equation in axisymmetry. Theproblems in consideration are cylindrical bounded domains, the scattering of plane wave in poroe-lastic by penetrable/impenetrable circular obstacles and lastly fluid-solid interaction problem withcircular solid obstacles for closed, open and intermediate pore boundary type. Since we have an-alytic expressions for the coefficients / transmission matrices, well-posedness is investigated byprobing for zeros of the determinant of these matrices. Our investigation includes the effect ofmaterial parameters and different degrees of viscosity. The first novelty of the work is the proposalof a definition of outgoing solutions for isotropic poroelasticity. The second novelty is the obser-vation that there are modes in fluid-poroelastic interaction problems without viscosity which arethe equivalent of Jones’ modes for fluid-elastic problem, and that these modes cease to exist in thepresence of viscosity. We found out that the presence of viscosity removes the eigenvalues, whichexist without viscosity and whose existence is expected for bounded domains.Dans ce rapport, nous étudions les équations poroélastiques isotropes axisymétriques dans différentes configurations pour lesquelles nous avons construit des solutions analytiques et étudié numériquement que le problème est bien posé. Nous nous sommes intéressés à des domaines cylindriques bornés, à la diffraction d’une onde plane dans un milieu poroélastique par des obstacles circulaires pénétrables et impénétrables,et enfin à l’interaction fluide-solide. Puisque nous avons obtenu les expressions analytiques des matrices de coefficients, nous pouvons étudier le déterminant de ces matrices pour déterminer le caractère bien-posé du problème. Notre étude inclut l’effet des paramètres du matériau et de la valeur de la viscosité. La première nouveauté de ce travail est la proposition d’une définition de solutions sortantes pour des problèmes poro-élastiques isotropes. Deuxièmement, nous avons observé des modes pour des problèmes d’interaction fluides-poroélastiques, équivalents aux modes de Jones, qui ne sont pas présents quand le milieu est visqueux. De même, nous avons noté que la présence de viscosité élimine les valeurs propres, qui existent pourtant sans viscosité et sont attendues pour des domaines bornés

Implementation of HDG method for 2D anisotropic poroelastic first-order harmonic equations

In this report, we develop a Hybridizable Discontinuous Galerkin (HDG) methodapplied to solving the two-dimensional anisotropic poroelastic equations written as a first-ordersystem in the frequency domain. We motivate the choice of the HDG method by the complexity ofthe considered equations and the high number of unknowns. The HDG method possesses indeedall the advantages of Discontinuous Galerkin method (hp-adaptivity, accuracy, ability to modelrugged domain,...) without its main drawback, the dramatic increase of the number of degrees offreedom. We illustrate the accuracy of the proposed solution methodology thanks to numericalexperiments and comparisons with analytical solutions that were developed in another work. Wealso offer numerical implementations on realistic geophysical media.Ce rapport présente le développement d’une méthode Galerkin Discontinue Hybride (HDG) appliquée aux équations poro élastiques anisotropes en deux dimensions écrites au premier ordre dans le domaine fréquentiel. Nous expliquons le choix de la méthode HDG par la complexité des équations considérées et le nombre élevé d’inconnues. Cette méthode possède en effet tous les avantages de la méthode Galerkin Discontinue (hp-adaptivité, précision, capacité modéliser des domaines complexes...) sans son principal inconvénient,l’augmentation du nombre de degrés de liberté. Nous illustrons la précision de la méthode proposée grâce à des tests numériques et des comparaisons avec des solutions analytiques qui ont été développées dans un autre travail, sur des milieux géophysiques raliste

Community-led digital literacy training : towards a conceptual framework

An exploratory study investigated the factors affecting digital literacy training offered by local community organizations, such as public libraries. Theory based on the educational assessment and information literacy instruction literatures, community informatics, and situated learning theory served as a lens of investigation. Case studies of two public libraries and five other local community organizations were carried out. Data collection comprised: one-on-one interviews with administrators, instructors, and community members who received training; analysis of training documents; observations of training sessions; and a survey administered to clients who participated in these training sessions. Data analysis yielded the generation of a holistic conceptual framework. The framework identifies salient factors of the learning environment and program components that affect learning outcomes arising from digital literacy training led by local community organizations. Theoretical propositions are made. Member checks confirmed the validity of the study's findings. Results are compared to prior theory. Recommendations for practice highlight the need to organize and train staff, acquire sustainable funding, reach marginalized populations, offer convenient training times to end-users, better market the training, share and adopt best practices, and better collect and analyze program performance measurement data. Implications for future research also are identified.Social Sciences and Humanities Research Council of Canada.http://wileyonlinelibrary.com/journal/asihj2023Information Scienc

Implementation of Hybridizable Discontinuous Galerkin method for time-harmonic anisotropic poroelasticity in two dimensions.

International audienceWe apply a Hybridizable Discontinuous Galerkin (HDG) method to numerically solve two-dimensional anisotropic poroelastic wave equations in the frequency domain given by Biot theory. The motivation for choosing HDG method comes from the complexity of the considered equations and the high number of unknowns. The HDG method possesses all the advantages of Discontinuous Galerkin method (hpadaptivity, accuracy, ability to model complex tectonics,...) without a drastic increase in the number of degrees of freedom. After a description of its implementation, we illustrate the accuracy of the proposed method by comparisons with analytical solutions. We then perform a sensitivity analysis of the method as a function of stabilization parameters and frequency, and show in particular that there exists optimal values of these parameters in order to obtain a very good level of accuracy. We also show the ability of the method to reproduce the different types of poroelastic waves including the slow Biot wave

Condition limite absorbante de bas ordre pour les équations poroélastiques isotropes en deux dimensions

In this report, we construct a low order absorbing boundary condition (ABC) for two-dimensional isotropic poroelasticity in frequency domain. The ABC is obtained for circular geometry by approximating the behavior of the analytical outgoing wave solution. The ABC is then extended to general non-circular domains and implemented with Hybridizable Discontinuous Galerkin (HDG) method. In circular symmetry, using the form of the exact solution, the robustness of the ABC is evaluated for the problem of scattering of planewave by a circular obstacle. We also compare the performance of this ABC with Perfectly Matched Layers, both coupled with HDG method. All of our numerical tests are performed on geophysical realistic media.Dans ce rapport, nous construisons une condition limite absorbante (CLA) de bas ordre pour la poroélasticité isotrope en deux dimensions et dans le domaine fréquentiel. La CLA est obtenue analytique-ment pour des géométries circulaires en approximant l’expression exacte de l’onde sortante pour les équations poroélastiques. Cette condition est étendue à des géométries quelconques et mise en oeuvre numériquement avec la méthode de Galerkin Discontinue Hybridizable (HDG). La robustesse de la CLA est évaluée en géométrie circulaire pour le problème de la diffraction des ondes planes par un obstacle. Nous comparons aussi la performance de cette CLA avec celle des couches parfaitement adaptées (PML), couplées à la méthode HDG. Tous les tests numériques sont effectués sur des matériaux géophysiques réalistes