14,925 research outputs found

    Honeylocust Twig-gall Midge (Diptera: Cecidomyiidae) in Michigan

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    Emergence and oviposition data were gathered for Neolasioptera brevis, a recently described pest of honeylocust. In 1984 the insects first emerged on 21 May and first oviposited on 4 June; in 1985 they first emerged on 28 April and first oviposited between 5-20 May. Average raceme length at emergence and at oviposition were 2.7 and 4.4 cm in 1984 and 2.6 and 4.8 cm in 1985. Approximate duration of the emergence period was one week. In 1985 observed oviposition wounds averaged 0.5/cm

    Helium energy levels including mα6m \alpha^6 corrections

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    The mα6m \alpha^6 correction to energy is expressed in terms of an effective Hamiltonian H(6)H^{(6)} for an arbitrary state of helium. Numerical calculations are performed for n=2n=2 levels, and the previous result for the 23P2^3P centroid is corrected. While the resulting theoretical predictions for the ionization energy are in moderate agreement with experimental values for 23S12^3S_1, 23P2^3P, and 21S02^1S_0 states, they are in significant disagreement for the singlet state 21P12^1P_1.Comment: 11 pages, with erratum submitted to Phys. Rev. A (2007

    Abelian link invariants and homology

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    We consider the link invariants defined by the quantum Chern-Simons field theory with compact gauge group U(1) in a closed oriented 3-manifold M. The relation of the abelian link invariants with the homology group of the complement of the links is discussed. We prove that, when M is a homology sphere or when a link -in a generic manifold M- is homologically trivial, the associated observables coincide with the observables of the sphere S^3. Finally we show that the U(1) Reshetikhin-Turaev surgery invariant of the manifold M is not a function of the homology group only, nor a function of the homotopy type of M alone.Comment: 18 pages, 3 figures; to be published in Journal of Mathematical Physic

    Evidence of Double Phonon Excitations in ^{16}O + ^{208}Pb Reaction

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    The fusion cross-sections for ^{16}O + ^{208}Pb, measured to high precision, enable the extraction of the distribution of fusion barriers. This shows a structure markedly different from the single-barrier which might be expected for fusion of two doubly-closed shell nuclei. The results of exact coupled channel calculations performed to understand the observations are presented. These calculations indicate that coupling to a double octupole phonon excited state in ^{208}Pb is necessary to explain the experimental barrier distributions.Comment: 6 pages, 2 figures, To be published in the Proceedings of the FUSION 97 Conference, South Durras, Australia, March 1997 (J. Phys. G

    Global Optical Control of a Quantum Spin Chain

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    Quantum processors which combine the long decoherence times of spin qubits together with fast optical manipulation of excitons have recently been the subject of several proposals. I show here that arbitrary single- and entangling two-qubit gates can be performed in a chain of perpetually coupled spin qubits solely by using laser pulses to excite higher lying states. It is also demonstrated that universal quantum computing is possible even if these pulses are applied {\it globally} to a chain; by employing a repeating pattern of four distinct qubit units the need for individual qubit addressing is removed. Some current experimental qubit systems would lend themselves to implementing this idea.Comment: 5 pages, 3 figure

    Complementary Methods for Volcanic Seismic Source Discrimination

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    ABSTRACT FINAL ID: V53E-2673 TITLE: Complementary Methods for Volcanic Seismic Source Discrimination SESSION TYPE: Poster SESSION TITLE: V53E. Surveillance of Volcanic Unrest: New Developments in Multidisciplinary Monitoring Methods IV Posters AUTHORS (FIRST NAME, LAST NAME): Charlotte A Rowe1, Susanna M R Falsaperla2, Emily Morton3, Horst K Langer2, Boris Behncke2 INSTITUTIONS (ALL): 1. Los Alamos Natl Lab, Los Alamos, NM, United States. 2. Istituto Nazionale di Geofisica e Volcanologia, Catania, Italy. 3. Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, Socorro, NM, United States. Title of Team: ABSTRACT BODY: We explore the success rates of detection and classification algorithms as applied to seismic signals from active volcanoes. The subspace detection method has shown some success in identifying repeating (but not identical) signals from seismic swarm sources, as well as pulling out nonvolcanic long period events within subduction zone tremor. We continue the exploration of this technique as applied to both discrete events and variations within volcanic tremor to determine optimal situations for its use. We will demonstrate both three-dimensional and subband applications both on raw waveforms and derived features such as skewness and kurtosis. The application can be used in both a supervised (select templates and compare) as well as unsupervised (cross-compare all samples and apply clustering to the matrix of comparisons). We compare the method to that of the KKAnalysis tool, which uses a self-organizing map approach to unsupervised clustering for feature vectors derived from the seismic waveforms. We will present a comparison of this method as applied to waveform features, spectral features and time-varying higher-order statistics as well as signal polarization, to elucidate the tools which show the best promise for problematic discrimination tasks

    Fusion barrier distributions in systems with finite excitation energy

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    Eigen-channel approach to heavy-ion fusion reactions is exact only when the excitation energy of the intrinsic motion is zero. In order to take into account effects of finite excitation energy, we introduce an energy dependence to weight factors in the eigen-channel approximation. Using two channel problem, we show that the weight factors are slowly changing functions of incident energy. This suggests that the concept of the fusion barrier distribution still holds to a good approximation even when the excitation energy of the intrinsic motion is finite. A transition to the adiabatic tunneling, where the coupling leads to a static potential renormalization, is also discussed.Comment: 9 pages, 4 figures, Submitted to Physical Review
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