14,973 research outputs found

    Four new species of Acoma Casey, with a key to species in the genus (Coleoptera: Scarabaeidae: Melolonthinae)

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    Acoma howdenorum, Acoma westcotti, Acoma quadrilaminata, and Acoma cimarron (Coleoptera: Scarabaeidae: Melolonthinae), all new species, are described from Yuma County, Arizona, USA, and Baja California Sur, Baja California (Norte), and Sonora, Mexico, respectively. Habitus of the four new species is illustrated, and an updated key to the described species in the genus is provided. Distribution and variation of Acoma glabrata Cazier are also discussed

    A revision of the genus Gymnetina Casey, 1915 (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini)

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    The genus Gymnetina Casey (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini) is redescribed and revised. Three new species and one new subspecies are described: G. borealis Warner and Ratcliffe, G. grossepunctata Ratcliffe and Warner, G. howdeni Warner and Ratcliffe, and G. cretacea sundbergi Warner and Ratcliffe. Gymnetina salicis (Bates), new status, is removed from synonymy with G. cretacea (LeConte), and G. alboscripta (Janson) is transferred from Gymnetis MacLeay to Gymnetina becoming Gymnetina alboscripta (Janson), new combination. Redescriptions of previously known species, a key for identification, and illustrations of the six species are provided. A brief biogeographical analysis suggests that ancestral taxa dispersed northwards from Guatemala and Mexico to the southwestern United States

    Four new Aphodius Illiger from pocket gopher burrows in Arizona, Utah, Kansas and Nebraska (Coleoptera: Scarabaeidae: Aphodiinae)

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    We describe four new species of winter-active Aphodius (sensu lato) from pocket gopher burrows in Arizona, Utah, Kansas, and Nebraska: A. cacabatus, A. paulseni, A. skillmani, and A. utopensis. Diagnostic characters of all four species are illustrated

    Aggregate Price Effects of Institutional Trading: A Study of Mutual Fund Flow and Market Returns

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    We study the relation between market returns and aggregate flow into U.S. equity funds, using daily flow data. The concurrent daily relation is positive. Our tests show that this concurrent relation reflects flow and institutional trading affecting returns. This daily relation is similar in magnitude to the price impact reported for an individual institution's trades in a stock. Aggregate flow also follows market returns with a one-day lag. The lagged response of flow suggests either a common response of both returns and flow to new information, or positive feedback trading.

    Eccentric discs in binaries with intermediate mass ratios: Superhumps in the VY Sculptoris stars

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    We investigate the role of the eccentric disc resonance in systems with mass ratios q greater than 1/4, and demonstrate the effects that changes in the mass flux from the secondary star have upon the disc radius and structure. The addition of material with low specific angular momentum to its outer edge restricts a disc radially. Should the mass flux from the secondary be reduced, it is possible for the disc in a system with mass ratio as large as 1/3 to expand to the 3:1 eccentric inner Lindblad resonance and for superhumps to be excited.Comment: 6 pages with 7 figures, accepted by MNRA

    Charles Darwin and John Herschel

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    The influence of John Herschel on the philosophical thoughts of Charles Darwin, both through the former's book, Natural Philosophy, and through their meeting in 1836 at the Cape of Good Hope, is discussed. With Herschel having himself speculated on evolution just a few months before he met Darwin, it is probable that he stimulated at least the beginnings of the latter's lifelong work on the subject

    Disclination-mediated thermo-optical response in nematic glass sheets

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    Nematic solids respond strongly to changes in ambient heat or light, significantly differently parallel and perpendicular to the director. This phenomenon is well characterized for uniform director fields, but not for defect textures. We analyze the elastic ground states of a nematic glass in the membrane approximation as a function of temperature for some disclination defects with an eye towards reversibly inducing three-dimensional shapes from flat sheets of material, at the nano-scale all the way to macroscopic objects, including non-developable surfaces. The latter offers a new paradigm to actuation via switchable stretch in thin systems.Comment: Specific results for spiral defects now added. References to Witten, Mahadevan and Ben Amar now added
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