Determination of the LEP beam energy using radiative fermion-pair events

We present a determination of the LEP beam energy using “radiative return” fermion-pair events recorded at centre-of-mass energies from 183 to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy Working Group's standard calibration. Including the energy-averaged 11 MeV uncertainty in the standard determination, the beam energy we obtain from the OPAL data is higher than that obtained from the LEP calibration by View the MathML source0±34(stat.)±27(syst.)MeV

Germination of Veronica parnkalliana seeds in response to seasonal and fire cues

Veronica parnkalliana (Scrophulariaceae) is an endangered herb endemic to South Australia, with only six herbarium specimens recorded since its first collection in 1909. A targeted search of a fire scar in the Flinders Ranges during the spring of 2008 found prolific regeneration of the plant after a prescribed burn during the previous autumn. This post-fire discovery prompted an investigation into the seed germination requirements for this species. In vitro laboratory studies showed that germination was stimulated by gibberellic acid (GA3), heat or smoked water. A seed burial experiment suggested that an annual cycle of dormancy was present, as germination of seeds that were exhumed after spring and summer was stimulated by a combination of heat and smoked water, but this did not occur after autumn or winter. Seeds buried at different depths before a fire were later monitored for seedling emergence in situ, and germination of exhumed seeds was also assessed. The depth of seed burial was a critical factor affecting germination. Results indicated that V. parnkalliana is a fire-ephemeral species with morphophysiological dormancy. These findings will provide valuable direction for future conservation planning for this species.Jenny Guerin, Michael Thorpe, Dan Duval, Manfred Jusaitis and Phil Ainsle

The influence of ethanol as a solvent on the gibberellic acid-induced germination of Brachyscome and Allittia (Asteraceae) seeds

Published online 16 February 2018Gibberellic acid (GA₃) is routinely used as a germination stimulant for seeds. However, the methods used to dissolve GA₃ powder – particularly if using organic solvents – have the potential to affect germination outcomes. In this study we examined the influence of the solvent ethanol, used to dissolve GA₃, on the seed germination of 14 species of Brachyscome and two species of Allittia. These species are important Australian native composites with potential for use in habitat restoration. Seeds of 11 of these species were found to be particularly responsive to GA₃. However, the use of a low concentration of ethanol (0.5%) to dissolve GA₃ affected subsequent germination outcomes, with four species responding positively and eight negatively to this solvent. The pure effect of GA₃ was therefore masked by the presence of small concentrations of ethanol, whose effects varied between the species examined. Because of these potentially confounding effects of ethanol, we recommend the use of pure water for dissolution of GA₃ when testing seed germination responses in these genera.Rina Aleman, Manfred Jusaitis, Joan Gibbs, Phil Ainsley and Fleur Tive

Flavour independent search for Higgs bosons decaying into hadronic final states in e^(+)e^(−)e^(+)e^(−) collisions at LEP

A search for the Higgsstrahlung process e^(+)e^(−)→hZ is described, where the neutral Higgs boson h is assumed to decay into hadronic final states. In order to be sensitive to a broad range of models, the search is performed independent of the flavour content of the Higgs boson decay. The analysis is based on e^(+)e^(−) collision data collected by the OPAL detector at energies between 192 and 209 GeV. The search does not reveal any significant excess over the Standard Model background prediction. Results are combined with previous searches at energies around 91 and at 189 GeV. A limit is set on the product of the cross-section and the hadronic branching ratio of the Higgs boson, as a function of the Higgs boson mass. Assuming the hZ coupling predicted by the Standard Model, and a Higgs boson decaying only into hadronic final states, a lower bound of 104 GeV/c2104 GeV/c^(2) is set on the mass at the 95% confidence level

W boson polarisation at LEP2

This is the publisher's version, also available electronically from http://www.sciencedirect.com/science/article/pii/S0370269304002576

Multi-photon events with large missing energy in e+e−e+e− collisions at s=192–209 GeV

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Influence of seed dimorphism and provenance on seed morphology, dispersal, germination and seedling growth of Brachyscome ciliaris (Asteraceae)

Brachyscome ciliaris is a floriferous Australian native daisy, with potential for use as a horticultural species. The species is hardy and seeds are relatively easy to germinate, but it is unique within the Brachyscome genus in that seeds are distinctly dimorphic. Within a fruiting capitulum, ray seeds are smooth and narrow with a minute pappus, whereas disc seeds have broad flat wings with curled hairs and a longer pappus than that of ray seeds. Both seed morphs, collected from five populations of the species, were tested to determine differences in their morphology, germination speed and percentage, seedling growth and wind-dispersal characteristics. Ray seeds were generally lighter and smaller than disc seeds and their length varied significantly with provenance. Dormancy levels of the two seed morphs and growth of ray- and disc-derived seedlings did not differ significantly, but differences were significant among the five populations tested. Seeds germinated readily, and germination was optimal under winter or summer conditions and lower in spring or autumn. Seed production by plants raised from ray or disc seeds was identical, but Noora-sourced plants yielded more seed than did plants sourced from the other provenances tested. Seed size, germination and plant growth of B. ciliaris varied significantly among populations. Winged disc seeds were dispersed slightly further by wind than were wingless ray seeds. We concluded that dormancy, germination and seed-yield characteristics of B. ciliaris were all influenced more by seed provenance than by seed morph (ray or disc).Rina Aleman, Manfred Jusaitis, Joan Gibbs, Phillip Ainsley, Fleur Tiver and Sophie Peti