125,050 research outputs found

    Nonparametric Regression using the Concept of Minimum Energy

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    It has recently been shown that an unbinned distance-based statistic, the energy, can be used to construct an extremely powerful nonparametric multivariate two sample goodness-of-fit test. An extension to this method that makes it possible to perform nonparametric regression using multiple multivariate data sets is presented in this paper. The technique, which is based on the concept of minimizing the energy of the system, permits determination of parameters of interest without the need for parametric expressions of the parent distributions of the data sets. The application and performance of this new method is discussed in the context of some simple example analyses.Comment: 10 pages, 4 figure

    Direct observation of voids in the vacancy excess region of ion bombarded silicon

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    The results reported in this letter indicate that the spatial separation of the vacancy and interstitial excesses which result from ion bombardment gives rise to stable voids upon annealing at 850 °C even for implants where the projected ion range is only of the order of a few thousand Ångstrom. Such voids have been observed directly by transmission electron microscopy. Furthermore, in cases where both voids and interstitial-based defects are present at different depths, it is found that Au has a strong preference for decorating void surfaces and hence Au can, indeed, be used as a selective detector of open volume defects in Si.One of the authors ~J.W.-L.! acknowledges the Australian Research Council for financial support

    ASSESSING THE ECONOMIC IMPACTS OF INTEGRATED PEST MANAGEMENT: LESSONS FROM THE PAST, DIRECTIONS FOR THE FUTURE

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    This paper reviews the literature assessing the economic impacts of integrated pest management (IPM). Definitions of IPM are categorized as input- or outcome-oriented, and an outcome- oriented definition is recommended for public program assessment. The literature on economic impact assessment of IPM is divided according to focus on expected profit, profitability risk, environment, and health. Measuring diverse impacts on the environment and health poses a challenge, as does placing a value on those impacts. Evaluation of environment and health variables has been accomplished either by comparing individual attributes (multiple criteria approach) or else by constructing a weighted index (index approach), which may be measured in monetary or non- monetary terms. While partial budgeting represents an accepted measure of short-term expected profitability effects of IPM practices, the three other focal areas are much more costly and complicated to measure. For routine IPM project assessments, simple indicators of health and environmental impacts are needed that can be used to extrapolate upon valuation measures from prior, published studies.Crop Production/Industries,

    Correlation functions of the One-Dimensional Random Field Ising Model at Zero Temperature

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    We consider the one-dimensional random field Ising model, where the spin-spin coupling, JJ, is ferromagnetic and the external field is chosen to be +h+h with probability pp and −h-h with probability 1−p1-p. At zero temperature, we calculate an exact expression for the correlation length of the quenched average of the correlation function ⟨s0sn⟩−⟨s0⟩⟨sn⟩\langle s_0 s_n \rangle - \langle s_0 \rangle \langle s_n \rangle in the case that 2J/h2J/h is not an integer. The result is a discontinuous function of 2J/h2J/h. When p=12p = {1 \over 2}, we also place a bound on the correlation length of the quenched average of the correlation function ⟨s0sn⟩\langle s_0 s_n \rangle.Comment: 12 pages (Plain TeX with one PostScript figure appended at end), MIT CTP #220

    Low noise tunnel diode receivers for satellite application

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    Low noise tunnel diode receivers for satellite application

    New results in rho^0 meson physics

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    We compare the predictions of a range of existing models based on the Vector Meson Dominance hypothesis with data on e^+ e^- -> pi^+ pi^$ and e^+ e^- -> mu^+ mu^- cross-sections and the phase and near-threshold behavior of the timelike pion form factor, with the aim of determining which (if any) of these models is capable of providing an accurate representation of the full range of experimental data. We find that, of the models considered, only that proposed by Bando et al. is able to consistently account for all information, provided one allows its parameter "a" to vary from the usual value of 2 to 2.4. Our fit with this model gives a point-like coupling (gamma pi^+ \pi^-) of magnitude ~ -e/6, while the common formulation of VMD excludes such a term. The resulting values for the rho mass and pi^+ pi^- and e^+e^- partial widths as well as the branching ratio for the decay omega -> pi^+ pi^- obtained within the context of this model are consistent with previous results.Comment: 34 pages with 7 figures. Published version also available at http://link.springer.de/link/service/journals/10052/tocs/t8002002.ht
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