14,899 research outputs found
Four new species of Acoma Casey, with a key to species in the genus (Coleoptera: Scarabaeidae: Melolonthinae)
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)
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)
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
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
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
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X-rays from cataclysmic variables
Cataclysmic Variables are a distinct class of interacting binaries, transferring mass from a donor star to a degenerate accretor, a white dwarf. We here review X-ray observations of these systems, with some emphasis on what has been achieved in the last decade
Disclination-mediated thermo-optical response in nematic glass sheets
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
Charles Darwin and John Herschel
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
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