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• 1
Electronic Resource
Oxford, UK : Blackwell Science Ltd
Weed research 45 (2005), S. 0
ISSN: 1365-3180
Source: Blackwell Publishing Journal Backfiles 1879-2005
Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes: Biological control of weeds by natural antagonists is of increasing interest. To reduce densities of the weed Cirsium arvense (creeping thistle) in a successional fallow, we applied spores of two pathogens, the biotrophic rust Puccinia punctiformis and the perthotrophic Phoma destructiva, for three consecutive years individually at different dates and combined. The proportion of systemically Puccinia punctiformis-infected C. arvense was not influenced by the treatments, but local rust infection was a good predictor of systemic infection in the following season. Artificial inoculations with P. destructiva increased the incidence of this pathogen in the third year as a result of synergistic effects, when co-inoculated with P. punctiformis. Inoculations with either pathogen had little effect on C. arvense shoot density, although there were transient reductions after combined inoculations with both fungi compared with the fungicide treatment. Cirsium arvense decreased from 60% to 5% cover within 3 years, while the cover of the co-occurring fallow vegetation increased. Under field conditions, with an already high degree of natural P. punctiformis infection, the effects of inoculations of the single pathogens were minor, but reductions in shoot density after combined inoculations indicate that this inoculation may have the potential to cause a decline of this weed.
Type of Medium: Electronic Resource
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• 2
Electronic Resource
Amsterdam : Elsevier
Nuclear Instruments and Methods in Physics Research Section A: 323 (1992), S. 373-379
ISSN: 0168-9002
Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
Topics: Physics
Type of Medium: Electronic Resource
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• 3
Electronic Resource
Springer
The European physical journal 1 (1998), S. 461-478
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. Data recorded by the JADE experiment at the PETRA ${\rm e^+e^-}$ collider were used to measure the event shape observables thrust, heavy jet mass, wide and total jet broadening and the differential 2-jet rate in the Durham scheme. For the latter three observables, no experimental results have previously been presented at these energies. The distributions were compared with resummed QCD calulations ( $\mathcal{O}(\alpha_s^2)$ +NLLA), and the strong coupling constant $\alpha_s(Q)$ was determined at different energy scales $Q=\sqrt{s}$ . The results, $\alpha_s(22 \mathrm{GeV}) = 0.161 ^{+0.016}_{-0.011} , \ \alpha_s(35 \mathrm{GeV}) = 0.143 ^{+0.011}_{-0.007} , \ \alpha_s(44 \mathrm{GeV}) = 0.137 ^{+0.010}_{-0.007} \; ,$ are in agreement with previous combined results of PETRA albeit with smaller uncertainties. Together with corresponding data from LEP, the energy dependence of $\alpha_s$ is significantly tested and is found to be in good agreement with the QCD expectation. Similarly, mean values of the observables were compared to analytic QCD predictions where hadronisation effects are absorbed in calculable power corrections.
Type of Medium: Electronic Resource
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• 4
Electronic Resource
Springer
The European physical journal 22 (2001), S. 1-15
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. A study of perturbative QCD calculations combined with power corrections to model hadronisation effects is presented. The QCD predictions are fitted to differential distributions and mean values of event shape observables measured in ${\mathrm{e^+e^-}$ annihilation at centre-of-mass energies from ${\sqrt{s}} =14$ to 189 GeV. We investigate the event shape observables thrust, heavy jet mass, C-parameter, total and wide jet broadening and differential 2-jet rate and observe a good description of the data by the QCD predictions. The strong coupling constant $\alpha_{\mathrm{S}}(M_{\mathrm{Z}^0})$ and the free parameter of the power correction calculations $\alpha_0({\mathrm{2 GeV}})$ are measured to be \begin{displaymath} \alpha_{\mathrm{Z}}(M_{\mathrm{Z}^0} = 0.1171^{+0.0032}_{-0.0020} \;\;\;\mathrm{and}\;\;\; \alpha_0({\mathrm{2 GeV}}) = 0.513^{+0.066}_{-0.045} \;\;\;. \end{displaymath} The predicted universality of $\alpha_0$ is confirmed within the uncertainties of the measurements.
Type of Medium: Electronic Resource
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