488 research outputs found

    Topic Map Generation Using Text Mining

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    Starting from text corpus analysis with linguistic and statistical analysis algorithms, an infrastructure for text mining is described which uses collocation analysis as a central tool. This text mining method may be applied to different domains as well as languages. Some examples taken form large reference databases motivate the applicability to knowledge management using declarative standards of information structuring and description. The ISO/IEC Topic Map standard is introduced as a candidate for rich metadata description of information resources and it is shown how text mining can be used for automatic topic map generation

    Cell lineage analysis of the mandibular segment of the amphipod Orchestia cavimana reveals that the crustacean paragnaths are sternal outgrowths and not limbs

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    The question of arthropod head segmentation has become one of the central issues in Evolutionary Developmental Biology. The number of theories pertaining to head segments progressively enlarges, old concepts have been revitalized, and nearly every conceivable composition of the arthropod head has at some point received discussion. One contentious issue involves a characteristic mouthpart in crustaceans – the lower lips or the so-called paragnaths. The paragnaths build the posterior border of the mouth region antagonistic to the upper lip – the labrum. We show here the development of the appendage-like structures in the mandibular region of the amphipod crustacean Orchestia cavimana at a high level of cellular resolution. The embryos are examined during development of the mouthparts using in vivo labeling. An invariant cell division pattern of the mandibular segment was detected by 4D-microscopy and a preliminary model for pattern of the first cleavages in the mandibular region created. With this indispensable precondition single ectodermal cells of the grid-like pattern were labeled with DiI – a lipophilic fluorescent dye – to trace cell lineages and determine the clonal composition of the developing mouthparts, especially the mandibular segment. From our data it is evident that the paragnaths are sternal outgrowths of the mandible segment. The assumption of the limb nature of paragnaths and the presence of an additional head segment between the mandibular and the second antennal segments are clearly refuted by our data. Our results show the power of cell lineage and clonal analyses for inferences on the nature, origin and thus homology of morphological structures. With this kind of investigation morphological and gene expression data can be complemented. We discuss notable similarities of paragnath anlagen to those of the hypopharynx complex in myriapods and hexapods. The fact that both structures grow out as two lateral buds in the same region of the mandibular sternite during development, and their important role in the formation of the feeding apparatus as a highly specialized chewing chamber in adults of crustaceans, myriapods, and hexapods argue for the paragnaths/hypopharynx anlagen being an additional potential apomorphy of Mandibulata

    The Traveling Salesman Problem Under Squared Euclidean Distances

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    Let PP be a set of points in Rd\mathbb{R}^d, and let α1\alpha \ge 1 be a real number. We define the distance between two points p,qPp,q\in P as pqα|pq|^{\alpha}, where pq|pq| denotes the standard Euclidean distance between pp and qq. We denote the traveling salesman problem under this distance function by TSP(d,αd,\alpha). We design a 5-approximation algorithm for TSP(2,2) and generalize this result to obtain an approximation factor of 3α1+6α/33^{\alpha-1}+\sqrt{6}^{\alpha}/3 for d=2d=2 and all α2\alpha\ge2. We also study the variant Rev-TSP of the problem where the traveling salesman is allowed to revisit points. We present a polynomial-time approximation scheme for Rev-TSP(2,α)(2,\alpha) with α2\alpha\ge2, and we show that Rev-TSP(d,α)(d, \alpha) is APX-hard if d3d\ge3 and α>1\alpha>1. The APX-hardness proof carries over to TSP(d,α)(d, \alpha) for the same parameter ranges.Comment: 12 pages, 4 figures. (v2) Minor linguistic change

    Psychologische Aspekte genetischer Beratung: Themenschwerpunkt: Beratung - wissenschaftlich und professionell eigenständig? Beratungsdialog I: Genetische Beratung

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    Psychologische Aspekte der genetischen Beratung werden erörtert. Einleitend wird darauf hingewiesen, dass genetische Beratung ein Kommunikationsprozess zwischen Berater und Klient bzw. Patient ist, in dem Probleme behandelt werden, die mit dem Auftreten oder der Befürchtung einer angeborenen und/oder genetisch bedingten Erkrankung oder Behinderung zusammenhängen. Dieser Prozess beinhaltet das Bemühen einer oder mehrerer entsprechend qualifizierter Personen, einem einzelnen oder einer Familie zum Verständnis medizinisch-genetischer Fakten zu verhelfen, Entscheidungsalternativen zu bedenken und individuell angemessene Verhaltensweisen zu wählen. Genetische Beratung erfolgt auf der Grundlage umfassender Anamneseerhebung und Befundbewertung, die deshalb als untrennbarer Bestandteil genetischer Beratung angesehen werden. Ein erstes Beratungsgespräch dauert in der Regel etwa eine Stunde, bei Bedarf werden wiederholt Gespräche angeboten. Bestandteil der genetischen Beratung ist in jedem Fall eine schriftliche Zusammenfassung für die Klienten bzw. Patienten, in der alle für die jeweilige Situation wichtigen Informationen allgemein verständnlich zusammengefasst sind. - Dem Beitrag folgen kritische Anmerkungen von R. Kollek zu Wolffs am klientenzentrierten Konzept orientierten Beratungsmodell

    Wissensextraktion durch linguistisches Postprocessing bei der Corpusanalyse

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    Der vorliegende Beitrag befaßt sich mit einem mehrstufigen Ansatz zur Analyse großer Textcorpora. Dabei liegt der Schwerpunkt auf der Untersuchung sekundärer, insbesondere linguistischer Filter für die Optimierung statistischer Analyseverfahren. Neben Beispielen für solche Filterverfahren werden auch praktische Anwendungen aufgezeigt

    Lectin prospecting in Colombian Labiatae. A systematic-ecological approach. - II

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    This is the second study of lectin and mucilage detection in Labiatae nutlets from Colombia. It was carried out on 31 taxa belonging to 7 genera in which no previous studies have been carried out in this field. A differential response was observed in the group of genera and species studied in terms of mucilage presence as well as lectin activity which consistently increased following extract treatment with Pectinex. Lectin activity was detected in 28 species, being important (greater than 60% activity) in at least 75% of them. Genera such as Hyptis, Scutellaria, Aegiphila and Lepechinia, whilst not presenting mucilage, did present lectin activity, having high activity in most cases. By contrast, Salvia (in all sections studied) presented mucilage and important lectin activity.Este es el segundo estudio sobre la presencia de mucílagos y lectinas en núculas de Labiadas colombianas. Se llevó a cabo en 31 taxones, pertenecientes a siete géneros, sobre los cuales no se disponía de información en este campo. Se observó una respuesta diferencial en los géneros y especies en lo relativo a la presencia de mucílago y a la actividad de lectina que se incrementó de manera consistente después de tratar los extractos con Pectinex. Se detectó actividad de lectina en 28 especies, siendo muy importante (mayor del 60%) en al menos 75% de ellas. Aunque los géneros Hyptis, Scutellaria, Aegiphila y Lepechinia no presentaron mucílago, su actividad de la lectina fue alta. Por el contrario Salvia (en todas las secciones estudiadas) presentó mucílago y una actividad importante de lectina.Peer reviewe
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