15,892 research outputs found

    Notes on \u3ci\u3eChrysomelobia Labidomerae\u3c/i\u3e (Acari: Heterostigmata: Podapolipidae), Parasites of \u3ci\u3eLabidomera Clivicollis\u3c/i\u3e (Coleoptera: Chrysomelidae) in Michigan and Wisconsin

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    Chrysomelobia labidomerae Eickwort, ectoparasitic mite of chrysomelid beetles, is reported from 11 Wisconsin counties, from 16 of 82 adult Labidomera clivicollis (Kirby) beetles wild-caught in Wisconsin, and from 27 of 141 presumably wild-caught L. clivicollis beetles from 13 Michigan counties. Wisconsin beetles harboring C. labidomerae were found in dry to wet-mesic, open habitats. A distribution map and comments are presented

    Inversion of Parahermitian matrices

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    Parahermitian matrices arise in broadband multiple-input multiple-output (MIMO) systems or array processing, and require inversion in some instances. In this paper, we apply a polynomial eigenvalue decomposition obtained by the sequential best rotation algorithm to decompose a parahermitian matrix into a product of two paraunitary, i.e.lossless and easily invertible matrices, and a diagonal polynomial matrix. The inversion of the overall parahermitian matrix therefore reduces to the inversion of auto-correlation sequences in this diagonal matrix. We investigate a number of different approaches to obtain this inversion, and and assessment of the numerical stability and complexity of the inversion process

    A comprehensive test of order choice theory: recent evidence from the NYSE

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    We perform a comprehensive test of order choice theory from a sample period when the NYSE trades in decimals and allows automatic executions. We analyze the decision to submit or cancel an order or to take no action. For submitted orders we distinguish order type (market vs. limit), order side (buy vs. sell), execution method (floor vs. automatic), and order pricing aggressiveness. We use a multinomial logit specification and a new statistical test. We find a negative autocorrelation in changes in order flow exists over five-minute intervals supporting dynamic limit order book theory, despite a positive first-order autocorrelation in order type. Orders routed to the NYSE’s floor are sensitive to market conditions (e.g., spread, depth, volume, volatility, market and individual-stock returns, and private information), but those using the automatic execution system (Direct+) are insensitive to market conditions. When the quoted depth is large, traders are more likely to “jump the queue” by submitting limit orders with limit prices bettering existing quotes. Aggressively-priced limit orders are more likely late in the trading day providing evidence in support of prior experimental results

    Systemic Risk and the Refinancing Ratchet Effect

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    The confluence of three trends in the U.S. residential housing market-rising home prices, declining interest rates, and near-frictionless refinancing opportunities-led to vastly increased systemic risk in the financial system. Individually, each of these trends is benign, but when they occur simultaneously, as they did over the past decade, they impose an unintentional synchronization of homeowner leverage. This synchronization, coupled with the indivisibility of residential real estate that prevents homeowners from deleveraging when property values decline and homeowner equity deteriorates, conspire to create a "ratchet" effect in which homeowner leverage is maintained during good times without the ability to decrease leverage during bad times. If refinancing-facilitated homeowner-equity extraction is sufficiently widespread-as it was during the years leading up to the peak of the U.S. residential real-estate market-the inadvertent coordination of leverage during a market rise implies higher correlation of defaults during a market drop. To measure the systemic impact of this ratchet effect, we simulate the U.S. housing market with and without equity extractions, and estimate the losses absorbed by mortgage lenders by valuing the embedded put-option in non-recourse mortgages. Our simulations generate loss estimates of 1.5trillionfromJune2006toDecember2008underhistoricalmarketconditions,comparedtosimulatedlossesof1.5 trillion from June 2006 to December 2008 under historical market conditions, compared to simulated losses of 280 billion in the absence of equity extractions.Risk; Financial Crisis; Household Finance; Real Estate; Subprime

    Terminal ruthenium carbido complexes as σ-donor ligands

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    The terminal carbido ligand of (Pcy_3)_2(Cl)_2RuC coordinates to other metal centers in a σ-donor fashion, as in (Pcy_3)_2(Cl)_2Ru≡C–Pd(Cl)_2(Sme_2) and (Pcy_3)_2(Cl)_2Ru≡C–Mo(CO)_5

    Spatial Models to Account for Variation in Observer Effort in Bird Atlases

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    To assess the importance of variation in observer effort between and within bird atlas projects and demonstrate the use of relatively simple conditional autoregressive (CAR) models for analyzing grid-based atlas data with varying effort. Pennsylvania and West Virginia, United States of America. We used varying proportions of randomly selected training data to assess whether variations in observer effort can be accounted for using CAR models and whether such models would still be useful for atlases with incomplete data. We then evaluated whether the application of these models influenced our assessment of distribution change between two atlas projects separated by twenty years (Pennsylvania), and tested our modeling methodology on a state bird atlas with incomplete coverage (West Virginia). Conditional Autoregressive models which included observer effort and landscape covariates were able to make robust predictions of species distributions in cases of sparse data coverage. Further, we found that CAR models without landscape covariates performed favorably. These models also account for variation in observer effort between atlas projects and can have a profound effect on the overall assessment of distribution change. Accounting for variation in observer effort in atlas projects is critically important. CAR models provide a useful modeling framework for accounting for variation in observer effort in bird atlas data because they are relatively simple to apply, and quick to run

    PRACTICES USED BY DAIRY FARMERS TO REDUCE SEASONAL PRODUCTION VARIABILITY

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    Results of this study further support the effectiveness of the seasonal pricing plan in reducing seasonal production variability. Florida Dairy farmers were able to change factors that affect production in order to take advantage of the seasonal pricing plan and that farmers that chose not to participate were able to affect factors to increase production seasonality.seasonality, Demand and Price Analysis, Livestock Production/Industries,
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