22,209 research outputs found

    Nuclear k_T in d+Au Collisions from Multiparticle Jet Reconstruction at STAR

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    This paper presents the most recent nuclear k_T measurements from STAR derived from multiparticle jet reconstruction of d+Au and p+p collisions at sqrt(s)=200 GeV. Since jets reconstructed from multiple particles are relatively free of fragmentation biases, nuclear k_T can be measured with greater certainty in this way than with traditional di-hadron correlations. Multi-particle jet reconstruction can also be used for a direct measurement of the fragmentation function.Comment: 4 pages, 3 figures, QM2005 Conference poster proceedings published in Acta Physica Hungarica

    Dr. J. E. McPherson, Educator and Researcher Extraordinaire: Biographical Sketch and List of Publications

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    (excerpt) Like many outstanding naturalists, John E. (“Jay”) McPherson grew up with a strong interest in the natural world, especially insects. This innate curiosity led him to enroll as a zoology major at San Diego State University in 1959. Upon completion of his undergraduate degree, he continued on to pursue his interest in insect biology, completing a Master’s thesis on the life history and morphology of a poorly known species of Notonectidae. Shortly thereafter, a teaching assistantship enabled him to pursue a Ph.D. at Michigan State University in East Lansing, where his research involved distinguishing two closely related species of bark beetles. During this period, Jay also worked on various pest species, including the cereal leaf beetle, pine tip beetle, and pine cone beetle

    The Ecology and Evolution of Ant- Aphid Interactions

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    The evolution of species interactions is a fascinating subject, and one of vital importance if we are to understand how biological communities change over time. This thesis considers the interaction between aphids (Homoptera) and ants (Formicidae). Ants tend aphids for sugary honeydew and in return provide a variety of protective services. A literature review in Chapter 1 introduces the subject and provides background information. Chapter 2 considers ant- aphid interactions in a community setting. Specifically, I consider the fitness effects of the ant- aphid interaction on host plants. Net benefits or costs to plants depend on the densities of ants and aphids; these densities may themselves change depending on context dependent factors. Chapters 3 and 4 consider how semiochemicals can allow species to respectively maintain or avoid synchrony in space and time with mutualists or antagonists. Chapter 3 shows ladybirds avoid prey patches guarded by ants by reducing oviposition in response to ant semiochemicals. Chapter 4 shows that aphid walking dispersal can be limited by ant semiochemicals. This may be adaptive for aphids to remain in areas of enemy- free space. Alternatively, if levels of kin competition are high limited dispersal could be costly to aphids. In Chapter 5 I consider interactions between invasive and native ants. Ecological dominance in ants may be mediated by the ability to monopolise honeydew- producing resources. Chapter 6 explores ants’ decisions whether to tend or prey upon aphids. Predation of aphids depends on colony demand (e.g. through cues from the presence of larvae) as well as the quality or quantity of supply (e.g. increased predation of unproductive aphids). Finally, Chapter 7 deals with macroevolutionary patterns in the interaction between ants and aphids. Specifically, I identify ecological traits that characterise aphid- tending ants. A final discussion chapter summarises how ant-aphid interactions fit into existing mutualism theory

    Model-Independent Bounds on R(J/ψ)R(J/\psi)

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    We present a model-independent bound on R(J/ψ) ⁣ ⁣BR(Bc+J/ψτ+ντ)/BR(Bc+J/ψμ+νμ)R(J/\psi) \! \equiv \! \mathcal{BR} (B_c^+ \rightarrow J/\psi \, \tau^+\nu_\tau)/ \mathcal{BR} (B_c^+ \rightarrow J/\psi \, \mu^+\nu_\mu). This bound is constructed by constraining the form factors through a combination of dispersive relations, heavy-quark relations at zero-recoil, and the limited existing determinations from lattice QCD. The resulting 95\% confidence-level bound, 0.20R(J/ψ)0.390.20\leq R(J/\psi)\leq0.39, agrees with the recent LHCb result at 1.3σ1.3 \, \sigma, and rules out some previously suggested model form factors.Comment: 19 pages, 4 figures, JHEP format, revised to match published versio

    Tropidosteptes forestierae (Hemiptera: Heteroptera: Miridae: Mirinae): a new species of Plant Bug injuring ornamental Florida Swampprivet, Forestiera segregata (Oleaceae), in South Florida

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    The mirine plant bug Tropidosteptes forestierae, new species (Hemiptera: Miridae) is described from Collier County, Florida, where it was found causing serious injury to an extensive ornamental hedge of Florida swampprivet, Forestiera segregata (Jacq.) Krug and Urb. (Oleaceae). Adult male and female, fifth instar, and egg are described. Color images of the adults, nymph, egg, and injury; scanning photomicrographs of selected adult structures; and illustrations of male genitalia are provided. A key to help distinguish the 16 species of Tropidosteptes known to occur in the southeastern United States is given

    Good approximate quantum LDPC codes from spacetime circuit Hamiltonians

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    We study approximate quantum low-density parity-check (QLDPC) codes, which are approximate quantum error-correcting codes specified as the ground space of a frustration-free local Hamiltonian, whose terms do not necessarily commute. Such codes generalize stabilizer QLDPC codes, which are exact quantum error-correcting codes with sparse, low-weight stabilizer generators (i.e. each stabilizer generator acts on a few qubits, and each qubit participates in a few stabilizer generators). Our investigation is motivated by an important question in Hamiltonian complexity and quantum coding theory: do stabilizer QLDPC codes with constant rate, linear distance, and constant-weight stabilizers exist? We show that obtaining such optimal scaling of parameters (modulo polylogarithmic corrections) is possible if we go beyond stabilizer codes: we prove the existence of a family of [[N,k,d,ε]][[N,k,d,\varepsilon]] approximate QLDPC codes that encode k=Ω~(N)k = \widetilde{\Omega}(N) logical qubits into NN physical qubits with distance d=Ω~(N)d = \widetilde{\Omega}(N) and approximation infidelity ε=O(1/polylog(N))\varepsilon = \mathcal{O}(1/\textrm{polylog}(N)). The code space is stabilized by a set of 10-local noncommuting projectors, with each physical qubit only participating in O(polylogN)\mathcal{O}(\textrm{polylog} N) projectors. We prove the existence of an efficient encoding map, and we show that arbitrary Pauli errors can be locally detected by circuits of polylogarithmic depth. Finally, we show that the spectral gap of the code Hamiltonian is Ω~(N3.09)\widetilde{\Omega}(N^{-3.09}) by analyzing a spacetime circuit-to-Hamiltonian construction for a bitonic sorting network architecture that is spatially local in polylog(N)\textrm{polylog}(N) dimensions.Comment: 51 pages, 13 figure
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