488 research outputs found
Topic Map Generation Using Text Mining
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
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
Let be a set of points in , and let be a
real number. We define the distance between two points as
, where denotes the standard Euclidean distance between
and . We denote the traveling salesman problem under this distance
function by TSP(). We design a 5-approximation algorithm for TSP(2,2)
and generalize this result to obtain an approximation factor of
for and all .
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 with , and we show that Rev-TSP is APX-hard if and . The APX-hardness proof carries
over to TSP 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
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
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
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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