12,616 research outputs found

    Crop Identification Technology Assessment for Remote Sensing (CITARS)

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    The results of classifications and experiments performed for the Crop Identification Technology Assessment for Remote Sensing (CITARS) project are summarized. Fifteen data sets were classified using two analysis procedures. One procedure used class weights while the other assumed equal probabilities of occurrence for all classes. In addition, 20 data sets were classified using training statistics from another segment or date. The results of both the local and non-local classifications in terms of classification and proportion estimation are presented. Several additional experiments are described which were performed to provide additional understanding of the CITARS results. These experiments investigated alternative analysis procedures, training set selection and size, effects of multitemporal registration, the spectral discriminability of corn, soybeans, and other, and analysis of aircraft multispectral data

    Crop identification technology assessment for remote sensing (CITARS). Volume 6: Data processing at the laboratory for applications of remote sensing

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    The results of classifications and experiments for the crop identification technology assessment for remote sensing are summarized. Using two analysis procedures, 15 data sets were classified. One procedure used class weights while the other assumed equal probabilities of occurrence for all classes. Additionally, 20 data sets were classified using training statistics from another segment or date. The classification and proportion estimation results of the local and nonlocal classifications are reported. Data also describe several other experiments to provide additional understanding of the results of the crop identification technology assessment for remote sensing. These experiments investigated alternative analysis procedures, training set selection and size, effects of multitemporal registration, spectral discriminability of corn, soybeans, and other, and analyses of aircraft multispectral data

    A new composite electrode architecture for energy storage devices

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    The research objective is to determine how the electrode microstructure (architecture) affect the performance of the nickel hydroxide electrochemical system. It was found that microstructure and additional surface area makes a difference. The best architectures are the FIBREX/nickel and nickel fiber composite electrodes. The conditioning time for full utilization was greatly reduced. The accelerated increase in capacity vs. cycling appears to be a good indicator of the condition of the electrode/active material microstructure and morphology. Conformal deposition of the active material may be indicated and important. Also higher utilizations were obtained; greater than 80 pct. after less than 5 cycles and greater than 300 pct. after more than 5 cycles using nickel fiber composite electrode assuming a 1 electron transfer per equivalent

    Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments across the Laurentian Great Lakes Region

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    Data from 104 sediment cores from the Great Lakes and “inland lakes” in the region were compiled to assess historical and recent changes in mercury (Hg) deposition. The lower Great Lakes showed sharp increases in Hg loading c. 1850-1950 from point-source water dischargers, with marked decreases during the past half century associated with effluent controls and decreases in the industrial use of Hg. In contrast, Lake Superior and inland lakes exhibited a pattern of Hg loading consistent with an atmospheric source - gradual increases followed by recent (post-1980) decreases. Variation in sedimentary Hg flux among inland lakes was primarily attributed to the ratio of watershed area: lake area, and secondarily to a lake’s proximity to emission sources. A consistent region-wide decrease (~20%) of sediment Hg flux suggests that controls on local and regional atmospheric Hg emissions have been effective in decreasing the supply of Hg to Lake Superior and inland lakes

    Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics

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    When ground state atoms are accelerated through a high Q microwave cavity, radiation is produced with an intensity which can exceed the intensity of Unruh acceleration radiation in free space by many orders of magnitude. The cavity field at steady state is described by a thermal density matrix under most conditions. However, under some conditions gain is possible, and when the atoms are injected in a regular fashion, the radiation can be produced in a squeezed state

    Resonant Kelvin-Helmholtz modes in sheared relativistic flows

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    Qualitatively new aspects of the (linear and non-linear) stability of sheared relativistic (slab) jets are analyzed. The linear problem has been solved for a wide range of jet models well inside the ultrarelativistic domain (flow Lorentz factors up to 20; specific internal energies 60c2\approx 60c^2). As a distinct feature of our work, we have combined the analytical linear approach with high-resolution relativistic hydrodynamical simulations, which has allowed us i) to identify, in the linear regime, resonant modes specific to the relativistic shear layer ii) to confirm the result of the linear analysis with numerical simulations and, iii) more interestingly, to follow the instability development through the non-linear regime. We find that very high-order reflection modes with dominant growth rates can modify the global, long-term stability of the relativistic flow. We discuss the dependence of these resonant modes on the jet flow Lorentz factor and specific internal energy, and on the shear layer thickness. The results could have potential applications in the field of extragalactic relativistic jets.Comment: Accepted for publication in Physical Review E. For better quality images, please check http://www.mpifr-bonn.mpg.de/staff/mperucho/Research.htm

    Quantum Mechanical Aspects of Cell Microtubules: Science Fiction or Realistic Possibility?

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    Recent experimental research with marine algae points towards quantum entanglement at ambient temperature, with correlations between essential biological units separated by distances as long as 20 Angstr\"oms. The associated decoherence times, due to environmental influences, are found to be of order 400 fs. This prompted some authors to connect such findings with the possibility of some kind of quantum computation taking place in these biological entities: within the decoherence time scales, the cell "quantum calculates" the optimal "path" along which energy and signal would be transported more efficiently. Prompted by these experimental results, in this talk I remind the audience of a related topic proposed several years ago in connection with the possible r\^ole of quantum mechanics and/or field theory on dissipation-free energy transfer in microtubules (MT), which constitute fundamental cell substructures. Quantum entanglement between tubulin dimers was argued to be possible, provided there exists sufficient isolation from other environmental cell effects. The model was based on certain ferroelectric aspects of MT. In the talk I review the model and the associated experimental tests so far and discuss future directions, especially in view of the algae photo-experiments.Comment: 31 pages latex, 11 pdf figures, uses special macros, Invited Plenary Talk at DICE2010, Castello Pasquini, Castiglioncello (Italy), September 13-18 201

    Asymptotic Infrared Fractal Structure of the Propagator for a Charged Fermion

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    It is well known that the long-range nature of the Coulomb interaction makes the definition of asymptotic ``in'' and ``out'' states of charged particles problematic in quantum field theory. In particular, the notion of a simple particle pole in the vacuum charged particle propagator is untenable and should be replaced by a more complicated branch cut structure describing an electron interacting with a possibly infinite number of soft photons. Previous work suggests a Dirac propagator raised to a fractional power dependent upon the fine structure constant, however the exponent has not been calculated in a unique gauge invariant manner. It has even been suggested that the fractal ``anomalous dimension'' can be removed by a gauge transformation. Here, a gauge invariant non-perturbative calculation will be discussed yielding an unambiguous fractional exponent. The closely analogous case of soft graviton exponents is also briefly explored.Comment: Updated with a corrected sign error, longer discussion of fractal dimension, and more reference
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