Search results for " element"
showing 10 items of 2679 documents
Comparative Study of the a Posteriori Error Estimators for the Stokes Problem
2007
The research presented is focused on a comparative study of a posteriori error estimation methods to various approximations of the Stokes problem. Mainly, we are interested in the performance of functional type a posterior error estimates and their comparison with other methods. We show that functional type a posteriori error estimators are applicable to various types of approximations (including non-Galerkin ones) and robust with respect to the mesh structure, type of the finite element and computational procedure used. This allows the construction of effective mesh adaptation procedures in all cases considered. Numerical tests justify the approach suggested.
Toxicological Impact of Rare Earth Elements (REEs) on the Reproduction and Development of Aquatic Organisms Using Sea Urchins as Biological Models
2022
The growing presence of lanthanides in the environment has drawn the attention of the scientific community on their safety and toxicity. The sources of lanthanides in the environment include diagnostic medicine, electronic devices, permanent magnets, etc. Their exponential use and the poor management of waste disposal raise serious concerns about the quality and safety of the ecosystems at a global level. This review focused on the impact of lanthanides in marine organisms on reproductive fitness, fertilization and embryonic development, using the sea urchin as a biological model system. Scientific evidence shows that exposure to lanthanides triggers a wide variety of toxic insults, includi…
Identification des compétences à l'école élémentaire :une approche empirique à partir des évaluations institutionnelles
2007
Cet article propose une analyse des résultats des élèves aux évaluations nationales, l’objectif étant de mieux comprendre comment les acquisitions se structurent à l’école primaire. L’intérêt de cette démarche réside principalement dans l’identification de compétences dont la maîtrise est essentielle à la réussite scolaire. L’approche choisie pour traiter la question est résolument empirique et se base sur l’examen des relations statistiques entre les items. Elle permet de répondre à plusieurs questions susceptibles d’intéresser les chercheurs en éducation, mais aussi les acteurs engagés, à différents degrés, dans le pilotage et la gestion pédagogique de l’enseignement primaire. Les évaluat…
Arbitrarily shaped plates analysis via Line Element-Less Method (LEM)
2018
Abstract An innovative procedure is introduced for the analysis of arbitrarily shaped thin plates with various boundary conditions and under generic transverse loading conditions. Framed into Line Element-less Method, a truly meshfree method, this novel approach yields the solution in terms of the deflection function in a straightforward manner, without resorting to any discretization, neither in the domain nor on the boundary. Specifically, expressing the deflection function through a series expansion in terms of harmonic polynomials, it is shown that the proposed method requires only the evaluation of line integrals along the boundary parametric equation. Further, minimization of appropri…
Continuous images of arcs: Extensions of Cornette's Theorem
2015
In [J.L. Cornette “Image of a Hausdorff arc” is cyclically extensible and reducible Trans. Am. Math. Soc., 199 (1974), pp. 253–267], Cornette proved that a locally connected Hausdorff continuum X is the continuous image of an arc if and only if each of its cyclic elements is the continuous image of an arc. Cyclic elements form a closed null cover of X by retracts of X. We generalize Cornette's result to closed null covers of X with a dendritic structure. We give examples to show that some of our conditions are necessary and we pose some open questions.
Holocene climate variability in Central Germany and a potential link to the polar North Atlantic: A replicated record from three coeval speleothems
2016
Here, we present high-resolution trace element and stable isotope records from three coeval Holocene stalagmites from the Herbstlabyrinth cave system, Central Germany. All stalagmites were precisely dated using MC-ICPMS 230Th/U-dating. One stalagmite started to grow at 13.62 ± 0.13 ka BP, covering the late Glacial; the other two speleothems started to grow at 11.13 ± 0.08 and 10.26 ± 0.08 ka BP, respectively. The combined record covers the entire Holocene. The interpretation of the different climate proxies is supported by data from a detailed cave monitoring programme. Cold conditions during the Younger Dryas are reflected by intermittent stalagmite growth at the Herbstlabyrinth. The δ18O…
The Studio: Reflections and Issues Arising
1999
An advanced Telematic Studio was built at the University of Jyvaskyla to combine the latest technologies for local and distributed work and/or meetings. The objectives were to combine leading edge technologies with ethnographic design principles derived from CSCW and HCI to support a broad range of activities. We informed the design by studies of similar facilities on other sites. The Studio is popular, and it is easy to give glowing accounts of its use. Nevertheless, over three years a significant number of problems have arisen with both technologies and uses. Some of these are local. Others may be generalisable to any ‘cooperative building’. For example: problems with videoconferencing; i…
Cardinal invariants of cellular Lindelof spaces
2018
A space X is said to be cellular-Lindelof if for every cellular family $$\mathcal {U}$$ there is a Lindelof subspace L of X which meets every element of $$\mathcal {U}$$ . Cellular-Lindelof spaces generalize both Lindelof spaces and spaces with the countable chain condition. Solving questions of Xuan and Song, we prove that every cellular-Lindelof monotonically normal space is Lindelof and that every cellular-Lindelof space with a regular $$G_\delta $$ -diagonal has cardinality at most $$2^\mathfrak {c}$$ . We also prove that every normal cellular-Lindelof first-countable space has cardinality at most continuum under $$2^{<\mathfrak {c}}=\mathfrak {c}$$ and that every normal cellular-Lindel…
L’intelligenza divina come forma di vita in Aristotele
2018
On the grounds of Met. xii, 7 this contribution construes the Aristotelian god as a form of biological life and intelligence, its essential connotation, as a form of life. Life (zoè), a term that strictly means biological life, thought or rather the reflexivity of thought, whose “act is also a pleasure” belongs to the Aristotelian god. The latter characteristic is the main reason to argue that the Aristotelian god is, like the “heart”, “a living being in a living being”, in that living organism which amounts to the universe. Accordingly the skies and the cosmos itself are self-propelled and intelligent to Aristotle, who in De Philosophia wonders whether they are also endowed with sensations…
Enhancer trap infidelity in Drosophila optomotor-blind
2013
Reporter gene activity in enhancer trap lines is often implicitly assumed to mirror quite faithfully the endogenous expression of the "trapped" gene, even though there are numerous examples of enhancer trap infidelity. optomotor-blind (omb) is a 160 kb gene in which 16 independent P-element enhancer trap insertions of three different types have been mapped in a range of more than 60 kb. We have determined the expression pattern of these elements in wing, eye-antennal and leg imaginal discs as well as in the pupal tergites. We noted that one pGawB insertion (omb (P4) ) selectively failed to report parts of the omb pattern even though the missing pattern elements were apparent in all other 15…