9,802 research outputs found

    New Lepidoptera-Parasitoid Associations in Weedy Corn Plantings: A Potential Alternate Host for \u3ci\u3eOstrinia Nubilalis\u3c/i\u3e (Lepidoptera: Pyralidae) Parasitoids

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    Larvae of the common sooty wing, Pholisora catullus, and pupae of the yellow-collared scape moth, Cisseps Fulvicollis, were collected in corn plantings containing different manipulated, indigenous weed communities to determine if these Lepidoptera had parasitoid species in common with the European corn borer, Ostrinia nubilalis. Pholisora catullus larvae were collected from lambsquarter, Chenopodium album, and redroot pigweed, Amaranthus retroflexus, whereas pupae of C. Julvicollis were obtained from corn. Four parasitoid species were reared from P. catulIus: Cotesia pholisorae, Oncophanes americanu (Hymenoptera: Braconidae), Gambrus ultimus, and Sinophorus albipalpus (Hymenoptera: Ichneumonidae). Of these, O. americanus and S. albipalpus represent new host records. Gambrus ultimus, however, was probably parasitizing a primary parasitoid of P. catullus. Itoplectis conquisitor and Vulgichneumon brevicinctor (Hymenoptera: Ichneumonidae) were reared from C. fulvicollis; V. brevicinctor had not previously been associated with this host. Both species reared from C. fulvicollis and Gambrus ultimus have been reported from O. nubilalis

    The role of banks in the Brazilian Interbank Market: Does bank type matter?

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    This paper presents an empirical analysis of the Brazilian interbank network structure. The Brazilian interbank market clearly presents a topology that is compatible to the free-scale networks. This market is characterized by money centers, which have exposures to many banks and are the most important source of large amounts of lending. Therefore, they have important positions in the network taken into account by the minimal spanning tree and the power domination measures of the network. We also develop a methodology to compare di®erent banks and their relative importance in the network.

    Fluctuation Dynamics in US Interest Rates and the Role of Monetary Policy

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    This paper presents empirical evidence suggesting that the degree of long-range dependence in interest rates depends on the conduct of monetary policy. We study the term structure of interest rates for the US and find evidence that global Hurst exponents change dramatically according to Chairman Tenure in the Federal Reserve Board and also with changes in the conduct of monetary policy. In the period from 1960's until the monetarist experiment in the beginning of the 1980's interest rates had a significant long-range dependence behavior. However, in the recent period, in the second part of the Volcker tenure and in the Greenspan tenure, interest rates do not present long-range dependence behavior. These empirical findings cast some light on the origins of long-range dependence behavior in financial assets.

    Thin-Slice Forecasts of Gubernatorial Elections

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    We showed 10-second, silent video clips of unfamiliar gubernatorial debates to a group of experimental participants and asked them to predict the election outcomes. The participants' predictions explain more than 20 percent of the variation in the actual two-party vote share across the 58 elections in our study, and their importance survives a range of controls, including state fixed effects. In a horse race of alternative forecasting models, participants' visual forecasts significantly outperform economic variables in predicting vote shares, and are comparable in predictive power to a measure of incumbency status. Adding policy information to the video clips by turning on the sound tends, if anything, to worsen participants' accuracy, suggesting that naïveté may be an asset in some forecasting tasks.
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