32,440 research outputs found

    Spruce Budworm Egg Mass Density on Balsam Fir and White Spruce: Low Population Levels (Lepidoptera: Tortricidae)

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    As part of a study to develop improved foliage sampling methods for spruce budworm, Choristoneura fumiferana (Clemens), egg masses, two balsam fir (four in one stand), Abies balsamea, and two white spruce, Picea glauca, trees were chosen from each of five spruce- fir stands in Michigan\u27s Upper Peninsula in 1980. All stands had very low to low population densities. Each tree was completely enumerated so that the number of new egg masses, foliage surface area, and egg mass density could be determined for the entire tree, three crown classes, four quadrants, and the tree top. Results indicated (1) considerable tree-to- tree and stand-to-stand variation; (2) no meaningful or consistent differences among quad- rants within or between species; (3) the average density in white spruce trees was 3.2 times larger than that in balsam fir trees; (4) the tree-la-tree variation of density in white spruce trees was 8.4 times larger than that in balsam fir trees; (5) densities in the mid-crown, upper-crown, and tree top are considerably higher than that in the lower-crown for both species; the relative differences for balsam fir are about twice that of white spruce; and (6) on the average, density at mid-crown was close to that of the entire tree for balsam fir, but density at mid-crown was 17.9% lower than that of the entire tree for white spruce. These results have important implications to the development of sampling plans for estimating egg mass density in spruce-fir stands

    The Dynamic Impact of Periodic Review on Women’s Rights

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    Human rights treaty bodies have been frequently criticized as useless and the regime’s self-reporting procedure widely viewed as a whitewash. Yet very little research explores what, if any, influence this periodic review process has on governments’ implementation of and compliance with treaty obligations. We argue oversight committees may play an important role in improving rights on the ground by providing information for international and primarily domestic audiences. This paper examines the cumulative effects on women’s rights of self-reporting and oversight review, using original data on the history of state reporting to and review by the Committee on the Elimination of Discrimination against Women (CmEDAW). Using a dynamic approach to study the effects of the periodic review process, we find that self-reporting has a significant positive effect on women’s rights. We explore three clusters of evidence for the domestic mobilization mechanism: information provision through domestic civil society organizations; publicity and critique through the domestic media; and parliamentary attention, debate, and implementation of recommendations. This is the first study to present positive evidence on the effects of self-reporting on rights and to describe the mechanisms that link Geneva bodies with local politics. Our findings challenge the received wisdom that the process of reporting to these treaty bodies is basically useless

    Can Liars Ever Prosper.

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    The paper compares the optimal financial contracts of a firm which has private information over its expost revenues when the finance can be provided by either a single or two groups of investors. When they are the only investors we use a financial contract with non-contractible monitoring, in which the probabilities of cheating by the entrepreneur/firm and monitoring by investors are mutual best responses. The contract is written by the entrepreneur knowing that this equilibrium will subsequently occur. With a second group of investors who have no monitoring rights, we analyse a truth telling contract and a misrepresentation contract in which cheating and monitoring probabilities are chosen in a similar way to those of the single investor contract. The non monitoring investors learn the results of any monitoring for free. Our main results are that: the two investor group truth-telling contract achieves the second best despite the lack of commitment; this contract is only feasible under limited liability of investors if low state revenues are high enough. When low state revenues are too low for this then the two investor misrepresentation contract is optimal. This contract has a negative correlation between repayments to the two investor groups: the contract uses the non-monitoring group to smooth out the repayments of the entrepreneur optimally. This reduces his incentive to make false reports and mitigates the investor's incentive to monitor. A second result is that the two investor scenario is Pareto superior to the single investor model. We show that with unlimited liability on investor groups, the two investor misrepresentation contract is as good as the second best. Generally in this misrepresentation contract investors may have to make repayments to the firm rather than receive them. A further result is that the three party contract is always renegotiation-proof, as well as collusion-proof so long as the low state revenues are below the expected repayments of the monitor. Last we show that under limited liability the share of finance provided by the two is strictly positive and uniquely determined.financial contracts; multiple investors; no commitment.

    An error analysis of probabilistic fibre tracking methods: average curves optimization

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    Fibre tractography using diffusion tensor imaging is a promising method for estimating the pathways of white matter tracts in the human brain. The success of fibre tracking methods ultimately depends upon the accuracy of the fibre tracking algorithms and the quality of the data. Uncertainty and its representation have an important role to play in fibre tractography methods to infer useful information from real world noisy diffusion weighted data. Probabilistic fibre tracking approaches have received considerable interest recently for resolving orientational uncertainties. In this study, an average curves approach was used to investigate the impact of SNR and tensor field geometry on the accuracy of three different types of probabilistic tracking algorithms. The accuracy was assessed using simulated data and a range of tract geometries. The average curves representations were employed to represent the optimal fibre path of probabilistic tracking curves. The results are compared with streamline tracking on both simulated and in vivo data

    Regression Equations and Table for Estimating Numbers of Eggs in Jack Pine Budworm (Lepidoptera: Tortricidae) Egg Masses in Michigan

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    Three simple linear regression equations were developed to estimate the numbers of eggs in jack pine budworm, Choristoneura pinus pinus, egg masses in Michigan. One equation was developed for each of 2-row, 2-row +, and 3-row egg masses. A table of estimated numbers of eggs per egg mass is given for each of the three row types for egg mass lengths from 1 to 25 nun

    Considerations When Sampling Spruce Budworm Egg Masses on Balsam Fir and White Spruce in the Lake States: Low Population Levels

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    One cluster each of balsam fir, Abies balsamea, and white spruce, Picea glauca, trees was chosen from each of five stands of spruce-fir in Michigan\u27s Upper Peninsula. The foliage surface area and the number of new egg masses of the spruce budworm, Choristoneura fumiferana, were determined for each branch and the top of each tree. The effects, in terms of the bias and the variance of the estimator, of sampling in different parts of the tree and with various size branches were determined. Factors that the sampler should consider in developing sampling plans to estimate spruce bud worm egg mass densities in mixed spruce-fir stands were identified. Egg mass density and its per branch variance may be considerably higher in white spruce than in balsam fir. Sampling whole feasible branches at mid-crown yielded, in general, the most precise and accurate estimates of tree egg mass density
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