2,572 research outputs found

    Twisted cubics on cubic fourfolds

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    Phenomena and properties of geologic materials affecting microwaves - A review

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    Interaction of natural terrain properties with remote microwave sensin

    Strengthening the Cohomological Crepant Resolution Conjecture for Hilbert-Chow morphisms

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    Given any smooth toric surface S, we prove a SYM-HILB correspondence which relates the 3-point, degree zero, extended Gromov-Witten invariants of the n-fold symmetric product stack [Sym^n(S)] of S to the 3-point extremal Gromov-Witten invariants of the Hilbert scheme Hilb^n(S) of n points on S. As we do not specialize the values of the quantum parameters involved, this result proves a strengthening of Ruan's Cohomological Crepant Resolution Conjecture for the Hilbert-Chow morphism from Hilb^n(S) to Sym^n(S) and yields a method of reconstructing the cup product for Hilb^n(S) from the orbifold invariants of [Sym^n(S)].Comment: Revised versio

    Making space for art: a spatial perspective of disruptive and defensive institutional work in Venezuela’s art world

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    The physical and material aspects of space, such as geographical distance or boundaries, have social and symbolic consequences that impact how people influence and are influenced by institutions. Social actors can however contest how space is conceived, perceived and lived, thus making space a crucial lever in the disruption and defense of institutions. However, we lack understanding of the spatial aspects of such institutional struggles. In exploring how space is leveraged in institutional work, our study foregrounds the socio-political nature of space, building on and expanding the theorization of Lefebvre. We draw on an in depth longitudinal analysis of the material, social and symbolic aspects of the spatial dimensions of disruptive and defensive institutional work over the past twenty years in Venezuela’s art world. Following the Bolivarian Revolution in the late 1990s, the incoming government transformed the organization of the national cultural landscape, resulting in a prolonged period of institutional disruption and defense. We demonstrate that actors use the material, social, and symbolic dimensions of space to challenge and maintain their key values and practices, and that those three dimensions are intertwined

    Une synthèse des modèles de représentation des connaissances à base de Graphes Conceptuels et OWL

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    Nous présentons et comparons deux approches de modélisation, formelles et concrètes, pour représenter et manipuler des connaissances d’un domaine. Le modèle des graphes conceptuels permet de modéliser des connaissances en terme de graphes, basés sur un support. Cette approche de modélisation est intensionnelle, est munie d’une sémantique en logique du premier ordre, et fait l’hypothèse d’un monde fermé pour ses raisonnements. Le langage OWL permet de décrire des ontologies et des faits sur le Web, suivant une approche de modélisation extensionnelle. Il possède une sémantique issue des logiques de descriptions, et fait l’hypothèse d’un monde ouvert pour ses raisonnements

    Changes in the structure due to strong winds in forest areas in the Pantanal, Brazil.

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    The Pantanal climate presents marked seasonality and eventually strong winds occur, especially in the beginning of the rainy season, which may last from September or October until April. A phytosociological study was conducted to evaluate the effects of a strong wind on the composition and structure of two forest formations in Pantanal wetland, a semideciduous forest (19º 15’ 32’’S and 55º 45’ 23.7’’W) and a forested savanna - “cerradão” (19° 17’ 21’’S and 55º 45’ 8.9’’W), with trees with diameter at breast height (DBH) ? 5 cm. After the strong wind, a reduction of 6% of the basal area and volume in the semideciduous forest was observed, mainly due to the uprooting of Xylopia aromatica trees. In the forested savanna, the basal area and volume reduction was even higher; an estimated 10%, representing 69 uprooted trees per hectare, mainly of Copaifera martii trees. In both areas it was observed that the uprooted trees presented an average height and diameter bigger than the trees that remained intact. Usually, the trees that were uprooted presented higher wood density and the species that had broken branches had a lower density
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