55,187 research outputs found

    Attraction of Acorn-Infesting \u3ci\u3eCydia Latiferreana\u3c/i\u3e (Lepidoptera: Tortricidae) to Pheromone-Baited Traps

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    Males of acorn-infesting Cydia latiferreana are attracted to an equilibrium mixture of the four isomers of 8, 10-dodecadien-l-ol acetate, the virgin female-produced pheromone. Trap height relative to the height of trees in which traps are placed seems to be a significant factor influencing moth catches at attractant-baited traps. In an oak woodlot and in an oak nursery, catches of male moths were greater in traps placed near the upper periphery of the canopy than at traps deployed at lower levels in the tree. Practical application of pheromone-baited traps in a forest situation will require further study on lure formulation and on trap deployment under forest conditions

    Do countries default in “bad times”?

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    This paper uses a new dataset to study the relationship between economic output and sovereign default for the period 1820-2004. We find a negative but surprisingly weak relationship between output and default. Throughout history, countries have indeed defaulted during bad times (when output was relatively low), but they have also maintained debt service in the face of severe adverse shocks, and they have defaulted when domestic economic conditions were favorable. We show that this constitutes a puzzle for standard theories, which predict a much tighter negative relationship as default provides partial insurance against declines in output.Default (Finance) ; Debt

    Large-Alphabet Time-Frequency Entangled Quantum Key Distribution by means of Time-to-Frequency Conversion

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    We introduce a novel time-frequency quantum key distribution (TFQKD) scheme based on photon pairs entangled in these two conjugate degrees of freedom. The scheme uses spectral detection and phase modulation to enable measurements in the temporal basis by means of time-to-frequency conversion. This allows large-alphabet encoding to be implemented with realistic components. A general security analysis for TFQKD with binned measurements reveals a close connection with finite-dimensional QKD protocols and enables analysis of the effects of dark counts on the secure key size.Comment: 14 pages, 3 figures, submitte

    Urban structure and growth

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    Most economic activity occurs in cities. This creates a tension between local increasing returns, implied by the existence of cities, and aggregate constant returns, implied by balanced growth. To address this tension, we develop a theory of economic growth in an urban environment. We show how the urban structure is the margin that eliminates local increasing returns to yield constant returns to scale in the aggregate, thereby implying a city size distribution that is well described by a power distribution with coefficient one: Zipf's Law. Under strong assumptions our theory produces Zipf's Law exactly. More generally, it produces the systematic deviations from Zipf's Law observed in the data, namely, the underrepresentation of small cities and the absence of very large ones. In these cases, the model identifies the standard deviation of industry productivity shocks as the key element determining dispersion in the city size distribution. We present evidence that the dispersion of city sizes is consistent with the dispersion of productivity shocks in the data.

    The communications technology satellite and the associated ground terminals for experiments

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    General spacecraft operational characteristics of the Communications Technology Satellite are discussed with particular emphasis on communication system parameters. Associated used ground terminals are reviewed. Wideband communications are also discussed

    Higher Order Modulation Equations for a Boussinesq Equation

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    In order to investigate corrections to the common KdV approximation to long waves, we derive modulation equations for the evolution of long wavelength initial data for a Boussinesq equation. The equations governing the corrections to the KdV approximation are explicitly solvable and we prove estimates showing that they do indeed give a significantly better approximation than the KdV equation alone. We also present the results of numerical experiments which show that the error estimates we derive are essentially optimal
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