657 research outputs found

    Social and Economic Consequences of Forest Decline in Czechoslovakia

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    The forests of Czechoslovakia are seriously endangered by air pollution. Another factor contributing to forest decline could be the historical development of silviculture. The study discusses the contemporary state of forests in Czechoslovakia and the outlook to 2000. Continued forest decline could seriously endanger the non-timber functions of forests. The importance of the water-controlling function of forests and its economic efficiency are broadly discussed. The largest part of the paper deals with the influence of forest decline on recreation. Even with limited data, one can observe a continually growing demand for recreation in mountain areas with damaged forests. The reasons lie in the historical development and peculiar features of recreation in this socialist society. The difficulties of forecasting peoples' behavior and their recreational demands is recognized. The last part of the paper deals with the influence of forest decline on production in the wood-processing and pulp-and-paper industries and strategies for their future. It will be necessary to change the structure of the forest-products sector and to investigate the newest technologies for the best utilization of all wood grown, which due to forest damage and the ensuing compulsory sanitation fellings will increase first and then after some years decrease. The study shows that forest decline in Czechoslovakia will lead to high economic losses and high consequent costs and investments in future decades, and can also have serious social consequences even if none have yet been manifested

    Capturing Old-Growth Values for Use in Forest Decision-Making

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    Abstract Old-growth forests have declined significantly across the world. Decisions related to old growth are often mired in challenges of value diversity, conflict, data gaps, and resource pressures. This article describes old-growth values of citizens and groups in Nova Scotia, Canada, for integration in sustainable forest management (SFM) decision-making. The study is based on data from 76 research subjects who participated in nine field trips to forest stands. Research subjects were drawn from Aboriginal groups, environmental organizations, forestry professionals, and rural and urban publics. Diaries, group discussions, and rating sheets were used to elicit information during the field trips. Findings show that different elicitation techniques can influence the articulation of intensity with which some values are held. In addition, certain values are more often associated with old-growth than with other forest-age classes. Some values associated with old-growth are considered more important than others, and some silvicultural treatments are perceived to compromise old-growth values more than others. Demographic characteristics, such as constituency group, gender, and age, are shown to influence value priorities. Ideas on how to incorporate old-growth values into SFM decision-making are highlighted

    The continental margin is a key source of iron to the HNLC North Pacific Ocean

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    Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L07608, doi:10.1029/2008GL033294.Here we show that labile particulate iron and manganese concentrations in the upper 500 m of the Western Subarctic Pacific, an iron-limited High Nutrient Low Chlorophyll (HNLC) region, have prominent subsurface maxima between 100–200 m, reaching 3 nM and 600 pM, respectively. The subsurface concentration maxima in particulate Fe are characterized by a more reduced oxidation state, suggesting a source from primary volcagenic minerals such as from the Kuril/Kamchatka margin. The systematics of these profiles suggest a consistently strong lateral advection of labile Mn and Fe from redox-mobilized labile sources at the continental shelf supplemented by a more variable source of Fe from the upper continental slope. This subsurface supply of iron from the continental margin is shallow enough to be accessible to the surface through winter upwelling and vertical mixing, and is likely a key source of bioavailable Fe to the HNLC North Pacific.Funding from the US Department of Energy, Office of Science, Biological and Environmental Research Program (JB) and WHOI Postdoctoral Scholars program, the Richard B. Sellars Endowed Research Fund, and the Andrew W. Mellon Foundation Endowed Fund for Innovative Research (PL)

    Formation of the ηc\eta_c in Two-Photon Collisions at LEP

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    The two-photon width Γγγ\Gamma_{\gamma\gamma} of the ηc\eta_c meson has been measured with the L3 detector at LEP. The ηc\eta_c is studied in the decay modes π+ππ+π\pi^+\pi^-\pi^+\pi^-, π+π\pi^+\pi^-K+^+K^-, Ks0_s^0K±π^\pm\pi^\mp, K+^+Kπ0^-\pi^{0}, π+πη\pi^+\pi^-\eta, π+πη\pi^+\pi^-\eta', and ρ+ρ\rho^+\rho^- using an integrated luminosity of 140 pb1^{-1} at s91\sqrt{s} \simeq 91 GeV and of 52 pb1^{-1} at s183\sqrt{s} \simeq 183 GeV. The result is Γγγ(ηc)=6.9±1.7(stat.)±0.8(sys.)±2.0\Gamma_{\gamma\gamma}(\eta_c) = 6.9 \pm 1.7 (stat.) \pm 0.8 (sys.) \pm 2.0(BR) keV. The Q2Q^2 dependence of the ηc\eta_c cross section is studied for Q2<9Q^2 < 9 GeV2^{2}. It is found to be better described by a Vector Meson Dominance model form factor with a J-pole than with a ρ\rho-pole. In addition, a signal of 29±1129 \pm 11 events is observed at the χc0\chi_c0 mass. Upper limits for the two-photon widths of the χc0\chi_c0, χc2\chi_c2, and ηc\eta_c' are also given

    Study of Z Boson Pair Production in e+e- Collisions at LEP at \sqrt{s}=189 GeV

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    The pair production of Z bosons is studied using the data collected by the L3 detector at LEP in 1998 in e+e- collisions at a centre-of-mass energy of 189 GeV. All the visible final states are considered and the cross section of this process is measured to be 0.74 +0.15 -0.14 (stat.) +/- 0.04 (syst.) pb. Final states containing b quarks are enhanced by a dedicated selection and their production cross section is found to be 0.18 +0.09 -0.07 (stat.) +/- 0.02 (syst.) pb. Both results are in agreement with the Standard Model predictions. Limits on anomalous couplings between neutral gauge bosons are derived from these measurements

    Study of Z Boson Pair Production in e^+e^- Interactions at \sqrt{s}=192 - 202 GeV

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    The cross section for the production of Z boson pairs is measured using the data collected by the L3 detector at LEP in 1999 in e^+e^- collisions at centre-of-mass energies ranging from 192 GeV up to 202 GeV. Events in all the visible final states are selected, measuring the cross section of this process. The special case of final states containing b quarks is also investigated. All results are in agreement with the Standard Model predictions

    Search for Charginos with a Small Mass Difference with the Lightest Supersymmetric Particle at \sqrt{s} = 189 GeV

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    A search for charginos nearly mass-degenerate with the lightest supersymmetric particle is performed using the 176 pb^-1 of data collected at 189 GeV in 1998 with the L3 detector. Mass differences between the chargino and the lightest supersymmetric particle below 4 GeV are considered. The presence of a high transverse momentum photon is required to single out the signal from the photon-photon interaction background. No evidence for charginos is found and upper limits on the cross section for chargino pair production are set. For the first time, in the case of heavy scalar leptons, chargino mass limits are obtained for any \tilde{\chi}^{+-}_1 - \tilde{\chi}^0_1 mass difference

    Search for Scalar Leptons in e+e- collisions at \sqrt{s}=189 GeV

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    We report the result of a search for scalar leptons in e+e- collisions at 189 GeV centre-of-mass energy at LEP. No evidence for such particles is found in a data sample of 176 pb^{-1}. Improved upper limits are set on the production cross sections for these new particles. New exclusion contours in the parameter space of the Minimal Supersymmetric Standard Model are derived, as well as new lower limits on the masses of these supersymmetric particles. Under the assumptions of common gaugino and scalar masses at the GUT scale, we set an absolute lower limit on the mass of the lightest scalar electron of 65.5 Ge

    Direct Observation of Longitudinally Polarised W Bosons

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    The three different helicity states of W bosons, produced in the reaction e+e- -> W+W- -> l nu q q~ are studied using leptonic and hadronic W decays at sqrt{s}=183GeV and 189GeV. The W polarisation is also measured as a function of the scattering angle between the W- and the direction of the e- beam. The analysis demonstrates that W bosons are produced with all three helicities, the longitudinal and the two transverse states. Combining the results from the two center-of-mass energies and with leptonic and hadronic W decays, the fraction of longitudinally polarised W bosons is measured to be 0.261 +/- 0.051(stat.) +/- 0.016(syst.) in agreement with the expectation from the Standard Model
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