46,913 research outputs found

    Short-term Response of Holcus lanatus L. (Common Velvetgrass) to Chemical and Manual Control at Yosemite National Park, USA

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    One of the highest priority invasive species at both Yosemite and Sequoia and Kings Canyon national parks is Holcus lanatus L. (common velvetgrass), a perennial bunchgrass that invades mid-elevation montane meadows. Despite velvetgrass being a high priority species, there is little information available on control techniques. The goal of this project was to evaluate the short-term response of a single application of common chemical and manual velvetgrass control techniques. The study was conducted at three montane sites in Yosemite National Park. Glyphosate spotspray treatments were applied at 0.5, 1.0, 1.5, and 2.0% concentrations, and compared with hand pulling to evaluate effects on cover of common velvetgrass, cover of other plant species, and community species richness. Posttreatment year 1 cover of common velvetgrass was 12.1% 6 1.6 in control plots, 6.3% 6 1.5 averaged over the four chemical treatments (all chemical treatments performed similarly), and 13.6% 6 1.7 for handpulled plots. This represents an approximately 50% reduction in common velvetgrass cover in chemically- treated plots recoded posttreatment year 1 and no statistically significant reduction in hand pulled plots compared with controls. However, there was no treatment effect in posttreatment year 2, and all herbicide application rates performed similarly. In addition, there were no significant treatment effects on nontarget species or species richness. These results suggest that for this level of infestation and habitat type, (1) one year of hand pulling is not an effective control method and (2) glyphosate provides some level of control in the short-term without impact to nontarget plant species, but the effect is temporary as a single year of glyphosate treatment is ineffective over a twoyear period

    The role of tobacco taxes in starting and quitting smoking

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    The annual five per cent in real terms increase in tobacco taxes proposed in the recent White Paper on smoking has reaffirmed the commitment of successive United Kingdom governments to above inflation increases in tobacco taxation to encourage people to stop smoking. This paper presents evidence on the determinants of starting and quitting smoking using data from the British 'Health and Lifestyle Survey' and is the first to identify tax elasticities for starting and quitting smoking using British data. Self-reported individual smoking histories are coupled with a long time series for the tax rate on cigarettes to construct a longitudinal data set. Estimates are obtained for the impact of above inflation tax rises on the age of starting smoking and the number of years of smoking. The estimates of the tax elasticity of the age of starting smoking are +0.16 for men and +0.08 for women. The estimates of the tax elasticity of quitting are - 0.60 for men and -0.46 for women. These are robust to different specifications.Smoking initiation and cessation; Tobacco taxes; Duration analysis.

    The non-linear transient behavior of second, third and fourth order phase-locked loops

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    Non-linear transient behavior of second, third, and fourth order phase-locked loop

    Illinois Forest Game Investigations W-87-R-9, Quarterly Federal Aid Performance Report 1 July - 30 September 1987

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    Quarterly Federal Aid Performance Report W-87-R-9, 1 July - 30 September 1987; Study No. VII-D Harvest Strategies for Illinois Deer Herds, Urban Deer StudyReport issued on: September 30, 1987INHS Technical Report prepared for unspecified recipien

    Measurement of the production cross section of prompt J/ψ mesons in association with a W± boson in pp collisions at p s = 7 TeV with the ATLAS detector

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    The process pp → W±J/ψ provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb-1 of p s = 7TeV pp collisions at the LHC, the first observation is made of the production of W± + prompt J/ events in hadronic collisions, using W± → μ and J/ψ → μ+μ-. A yield of 27.4±7.5 -6.5 W± + prompt J/ψ events is observed, with a statistical significance of 5.1. The production rate as a ratio to the inclusive W± boson production rate is measured, and the double parton scattering contribution to the cross section is estimated

    Measurement of the azimuthal angle dependence of inclusive jet yields in Pb+Pb collisions at √sNN=2.76  TeV with the ATLAS detector

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    Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δϕ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δϕ dependence of jet yields in 0.14  nb-1 of √sNN=2.76  TeV Pb+Pb collisions at the LHC for jet transverse momenta pT>45  GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with Δϕ was characterized by the parameter, v2jet, and the ratio of out-of-plane (Δϕ∼π/2) to in-plane (Δϕ∼0) yields. Nonzero v2jet values were measured in all centrality bins for pT<160  GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions

    Exclusive J/ψJ/\psi and Υ\Upsilon photoproduction and the low xx gluon

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    We study exclusive vector meson photoproduction, γpV+p\gamma p \to V + p with V=J/ψV=J/\psi or Υ\Upsilon, at NLO in collinear factorisation, in order to examine what may be learnt about the gluon distribution at very low xx. We examine the factorisation scale dependence of the predictions. We argue that, using knowledge of the NLO corrections, terms enhanced by a large ln(1/ξ)\ln(1/\xi) can be reabsorbed in the LO part by a choice of the factorisation scale. (In these exclusive processes ξ\xi takes the role of Bjorken-xx.) Then, the scale dependence coming from the remaining NLO contributions has no ln(1/ξ)\ln(1/\xi) enhancements. As a result, we find that predictions for the amplitude of Υ\Upsilon production are stable to within about ±15%\pm 15\%. This will allow data for the exclusive process pppΥpp p \to p\Upsilon p at the LHC, particularly from LHCb, to be included in global parton analyses to constrain the gluon PDF down to x105x\sim 10^{-5}. Moreover, the study of exclusive J/ψJ/\psi photoproduction indicates that the gluon density found in the recent global PDF analyses is too small at low xx and low scales.Comment: 21 pages, 6 figures. Text significantly improved, references added, version to be published in J.Phys.

    Representation-theoretic derivation of the Temperley-Lieb-Martin algebras

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    Explicit expressions for the Temperley-Lieb-Martin algebras, i.e., the quotients of the Hecke algebra that admit only representations corresponding to Young diagrams with a given maximum number of columns (or rows), are obtained, making explicit use of the Hecke algebra representation theory. Similar techniques are used to construct the algebras whose representations do not contain rectangular subdiagrams of a given size.Comment: 12 pages, LaTeX, to appear in J. Phys.

    Measurement of the electroweak production of dijets in association with a Z-boson and distributions sensitive to vector boson fusion in proton-proton collisions at √s= 8 TeV using the ATLAS detector

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    Measurements of fiducial cross sections for the electroweak production of two jets in association with a Z-boson are presented. The measurements are performed using 20.3 fb−1 of proton-proton collision data collected at a centre-of-mass energy of s√ = 8 TeV by the ATLAS experiment at the Large Hadron Collider. The electroweak component is extracted by a fit to the dijet invariant mass distribution in a fiducial region chosen to enhance the electroweak contribution over the dominant background in which the jets are produced via the strong interaction. The electroweak cross sections measured in two fiducial regions are in good agreement with the Standard Model expectations and the background-only hypothesis is rejected with significance above the 5σ level. The electroweak process includes the vector boson fusion production of a Z-boson and the data are used to place limits on anomalous triple gauge boson couplings. In addition, measurements of cross sections and differential distributions for inclusive Z-boson-plus-dijet production are performed in five fiducial regions, each with different sensitivity to the electroweak contribution. The results are corrected for detector effects and compared to predictions from the Sherpa and Powheg event generators
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