267 research outputs found

    Description of GADEL

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    This article describes the first implementation of the GADEL system : a Genetic Algorithm for Default Logic. The goal of GADEL is to compute extensions in Reiter's default logic. It accepts every kind of finite propositional default theories and is based on evolutionary principles of Genetic Algorithms. Its first experimental results on certain instances of the problem show that this new approach of the problem can be successful.Comment: System Descriptions and Demonstrations at Nonmonotonic Reasoning Workshop, 2000 6 pages, 2 figures, 5 table

    Caractères biogéochimiques de la matière organique dans la colonne d'eau et les sédiments d'un écosystème saumâtre: l'étang de Thau - Variations saisonnières

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    Le long de la côte méditerranéenne française du Golfe du Lion, l'étang de Thau présente des caractères assez particuliers. Il est parfois soumis à des conditions anoxiques appelées "malaigues" qui résultent de l'accumulation de matières organiques durant la période chaude liée au développement des macrophytes. Ces dépôts organiques associés aux biomasses résultant des activités conchylicoles et aux apports extérieurs contribuent en cours d'année aux échanges biogéochimiques entre la colonne d'eau et les dépôts.Dans ce même milieu, l'analyse de la distribution et de la nature de la matière organique par des méthodes fines comme la chromatographie liquide haute performance ou la pyrolyse a permis de préciser son origine et son évolution dans la colonne d'eau et les dépôts. Durant les quatre saisons, les particularités de la matière organique ont donc été analysées en terme d'accumulation, de dégradation et de conservation. L'été constitue une période de production et de dégradation. L'automne est principalement caractérisé par des processus dégradatifs et des apports terrigènes (composés phénoliques). L'hiver correspond à une période de relative stabilité de la matière organique consécutive aux conditions froides. Le printemps enfin représente une période de reprise de l'activité biologique produisant une matière organique fraîche riche en sucres.Sous les tables conchylicoles on observe un accroissement de la matière organique dans la colonne d'eau et les dépôts. Mais les processus actifs de dégradation réduisent considérablement la quantité de matière organique déposée. Les résultats de ces mécanismes varient selon les stations sous table et hors table.Dans les dépôts les résultats de la dégradation dans la colonne d'eau amènent à une décroissance des composés biodégradables et à un accroissemenet des composés résistants comme les phénols et les hydrocarbures aromatiques. Ces processus de minéralisation s'accroissent vers la profondeur dans les dépôts au profit du pôle aromatique.Les relations entre les nutriments et la matière organique qui constitue à la fois leur source et leur puits se marquent bien sous les tables conchylicoles où les sels nutritifs s'accumulent en surface.The Thau lagoon along the French Mediterranean coast of the Gulf of Lions has unusual characteristics. It is sometimes subjected to anoxic conditions, known as "malaigues", which result from the accumulation of organic matter during the warmer period. Throughout the year this organic deposition, associated oyster farming and terrigenous inputs, contributes to biogeochemical exchanges between the water column and the underlying deposits. In this same environment, high-resolution analytical techniques (HPLC ; PY-GC-MS) were used to analyze the distribution and nature of the organic matter and to determine its origin and behaviour in the water column and sediments.Total suspended matter (TSM) was determined by filtration of water samples pumped up from different levels of the water column and filtered onto glass fiber filters (GF/F grade) previously heated at 450 °C for 4 hours. Particulate organic carbon (POC) was determined on the same samples with a Leco CS 125 analyzer after removal of inorganic carbonates by treatment with a H2 SO4 (2N) solution. Dissolved organic carbon (DOC) was determined on the filtrates using a Shimadzu TOC 5000 analyzer. The determination of polysaccharides in the TSM was achieved by a colorimetric method involving a H2 SO4 (3N) solution and anthrone reagent (Gallali 1972).Phenolic compounds were determined by high performance liquid chromatography (HPLC) after cupric oxide alkaline oxidation of TSM samples. The oxidized samples were acidified (HCl, 2N) and subjected to liquid-liquid extraction with ethyl acetate (Hartley & Buchan 1973; Hedges & Ertel 1982). The limit of detection is 10-4 g and the precision of the method is about 2% for each compound. Separation and quantification of phenolic monomers was carried out by HPLC (Hartley & Buchan, 1973 ; Serve et al., 1983). Of a total of 28 identified products, eleven represent the monomers constituting lignin and are taken into account according to Hedges & Parker (1976), Hedges & Mann (1979) and Hedges & Ertel (1982). The products of oxidative hydrolysis of lignin belong to the following three series : 4-hydroxybenzyl "H" (p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxyacetophenone), 3-methoxy-4-hydroxybenzylic "V" (Vanillyl) and 3,5-methoxy-4-hydroxybenzylic "S" (Syringyl). Each of these three series presents an alkyl side chain with 1, 2 or 3 carbon atoms. The compounds in C6-C1 can be acids or aldehydes, those in C6-C2 are ketones and those in C6-C3 are acids. The latter, having a phenylpropenic structure, belong to the Cinnamyl "C" series (ferulic acid, p-coumaric acid). Separation of phenols was carried out on a Merck analytical column (250 mm long x 4 mm in diameter) with a Lichrosorb reversed phase C18 stationary phase of 5 µm granulometry, equipped with a precolumn (40 mm long) containing the same phase. Elution was achieved with ternary eluents (water, acetonitrile, acetic acid), in a high pressure binary gradient (Charrière 1991). The eluted products were determined qualitatively, by comparison of their retention times with those of commercial products (detection in UV at 275 nm), after a co-injection if necessary, and quantitatively by an internal standard method (phloroglucinol : 1,3,5-benzenetriol and p-anisic acid : p-methoxybenzoic acid).Analysis of the major classes of organic compounds was carried out by coupled pyrolysis - gas chromatography - mass spectrometry. A CDS 1000 pyrolysis probe was directly fitted with a Perkin-Elmer 8700 gas chromatograph (GC) equipped with a TR-WAX capillary column (length: 30 m, diameter: 0.32 mm, phase thickness: 0.50 µm). Pyrolysis temperature was 700 °C for 10 s and the column temperature was programmed from 60°C to 240 °C at a rate of 6 °C/min according to Puigbo et al. (1989). Pyrolysis fragments were identified by coupling the GC to a HP 5989 mass spectrometer. Twenty three major peaks were selected on the pyrochromatograms and each selected compound was expressed as a percentage of the sum of the surface of these 23 peaks Pyrolysis products were grouped into five main families, each of them including similar molecules or closely related chemical structures: aromatic hydrocarbons, nitrogenous compounds, sugars, phenols and amino sugars.The survey of all these parameters showed some characteristic differences over the four seasons. Summer appears as a period when the biological production reaches maximum levels in the water column. At that time, organic matter is stratified with high levels of accumulation in the deeper layers. DOC is also abundant throughout the water column and organic compounds belonging to the class of sugars decrease according to depth. Autumn corresponds to Mediterranean storms and typical rainfalls. Terrestrial inputs increase in this season and degradative processes affect the organic matter that was produced in large quantities in the summer by the autotrophic organisms of the lagoon. DOC is recycled and reflects the degradation of autochthonous organic material. Winter, with reduced TSM levels related to low terrestrial inputs, is characterized by a homogenization of the water column and a weak biological activity. Lignin-derived phenols are abundant and correspond to a period of low biological activity. In contrast, in the spring the biological activity recovers, as indicated by the high sugar content of the DOC and by a homogenization of the water column.Under the oyster beds, an increase of organic matter is observed in the water column as well as in the sediments. However, the active degradation processes in summer and autumn reduce considerably the amount of the settling organic matter. The results of these processes are variable according to whether the stations are under or outside of the oyster beds. Degradation in the water column leads to a decrease of biodegradable compounds in the sediments and an increase in resistant compounds like phenols and aromatic hydrocarbons. These mineralization processes increase with depth in deposits, as reflected by higher proportions of aromatic compounds. The relationship between nutrients and organic matter, the latter constituting both their source and their sink, appears in sediments under oyster beds, where the inorganic nutrients accumulate at the surface

    Seminário de conclusão do projeto FRPLongDur

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    The FRPLongDur research project (reference no. POCI-01-0145-FEDER-016900) was financed by national funds through FCT and co-financed by the European Regional Development Fund (FEDER) through the Competitiveness and Internationalization Operational Program (POCI), and Lisbon Regional Operational Program. This project had as participating institutions at the University of Minho and the National Civil Engineering Laboratory. It also had the participation of Empa - Swiss Federal Laboratories for Materials Science and Technology. FRPLongDur aimed at contributing to the knowledge on the long-term behavior and durability of reinforced concrete elements strengthened with CFRP (Carbon Fiber Reinforced Polymers) laminates according to the EBR (Externally Bonded Reinforcement) and NSM (Near Surface Mounted) reinforcement techniques, under the effect of aging in real environments. The work involved: (i) an extended experimental program, with the creation of five experimental stations distributed throughout Portugal country, involving different environments (Elvas, Guimarães, Lisbon, Serra da Estrela and Viana do Castelo), where test specimens at three scales (material, connection and structure) were installed to evaluate its performance during the time; (ii) the development of numerical simulations, based on the results obtained in the monitoring carried out; and, (iii) making recommendations for the project. On the last 30th of October 2020, the seminar to conclude the FRPLongDur project took place in a Webinar mode, in which the main results were presented. The present eBook summarizes the presentations carried out

    A palaeoecological approach to neotectonics : the geomorphic evolution of the Ntem River in and below its interior delta, SW Cameroon

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    The Late Tertiary to Quaternary evolution of the Ntem interior delta in SW Cameroon shall be modelled. A step fault was formed along neotectonically remobilized Precambrian structures. Uncalibrated 14C-datations in this ‘sediment trap’ show Pleistocene to Holocene ages. Both within and below the interior delta pebbles and clasts which are cemented in an iron and manganese matrix were found. These ‘fanglomerates’ are used to discuss different processes of the younger evolution also concerning climatic fluctuations in the study area

    Ecological zonation of the hyperhaline estuary of the Casamance river (Senegal) : Foraminifera, zooplanktoon and abiotic variables

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    Due to a long-lasting drought afflicting the Sahel, the Casamance River has been transformed into a hyperhaline estuary, with salinities up to 170 °/°° at a distance of 210 km from the sea. Foraminifera and zooplankton populations both show a marked decrease in the number of species in increasingly confined water, the distribution of species being closely related to the evolution ofabiotic variables. Our three-prong study allowed us to identify six zones, upwards from the sea. The uppermost ones are characterized by drastic conditions which considerably reduce the number of species. Therefore, the populations of Foraminifera, zooplankton and even fish become oligo or mono specific. The Casamance river appears to fit quite well into the general rules concerning hyperhaline environments. However, it shows some peculiar features which are : the large dimensions of the hyperhaline estuary (over 230 km long and over 5 km wide in the lower course); peak salinities among the highest known for a permanently open estuary (up to 170°/°°); and water remaining trapped inside the river for several years. (Résumé d'auteur

    Parnassus 2017

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    The 2017 edition of the student literary journal, Parnassus, published by Taylor University in Upland, Indiana

    The Fate of the Consonantal Root and the Binyan in Optimality Theory

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    Cet article propose une analyse de la morphologie non-concaténative en hébreu moderne dans le cadre de la Théorie de l'Optimalité. Il est soutenu que le mot est la base de la dérivation, modifiée par des contraintes assignant une structure prosodique, une mélodie vocalique et des affixes, le cas échéant. La notion de gabarit est vue comme une configuration des structures assignées par ces contraintes. La racine consonantique est entièrement éliminée de la grammaire. Ce dernier point est défendu sur la base d'arguments provenant du changement diachronique et de l'apprentissage.The paper provides an Optimality Theoretic account to Modern Hebrew non-concatenative morphology. It argues that the base of derivation is the word/stem, modified by constraints assigning the prosodic structure, the vocalic pattern, and the affixes (if any). The notion of the binyan is viewed as a configuration of the structures assigned by these constraints. The consonantal root is entirely eliminated from the grammar, a result supported by arguments from historical change and learnability
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