1,072 research outputs found

    Germination responses of a dry sclerophyll forest soil-stored seedbank to fire related cues

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    Fire is an integral component of many ecosystems worldwide. Many plant species require fire-related cues, primarily heat and smoke, to trigger germination. Despite the importance of this process, the responses of many Australian species to these cues are unknown. Without this knowledge fire management strategies may be developed that are inappropriate for individual species and vegetation communities. In this study we examined the responses of a dry sclerophyll forest seed bank to heat and smoke germination cues. Analysis was possible for 48 taxa within the soil seedbank with 34 of these showing a response to one or both of the germination cues. 10 species responded to the heat treatment, 11 species responded to the smoke treatment and 13 species responded to both the heat and smoke treatments. Germination cues acted independently for all species considered. Results in this study were consistent with published reports for most species, although some differences were seen at the species and genus level. The study highlights the importance of fire-related cues in enhancing germination of a large proportion of the species occurring in dry sclerophyll forests

    Do preserved foods increase prostate cancer risk?

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    Preserved foods have been found in some studies to be associated with increased cancer risks. The possible relationship between preserved foods and prostate cancer was investigated in a case–control study in southeast China during 2001–2002 covering 130 histologically confirmed cases and 274 inpatient controls without malignant disease. The total amount of preserved food consumed was positively associated with cancer risk, the adjusted odds ratio being 7.05 (95% CI: 3.12–15.90) for the highest relative to the lowest quartile of intake. In particular, the consumption of pickled vegetables, fermented soy products, salted fish and preserved meats was associated with a significant increase in prostate cancer risk, all with a significant dose–response relationship

    Energy spectra of elements with 18 or = Z or = 28 between 10 and 300 GeV/amu

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    The HEAO-3 Heavy Nuclei Experiment is composed of ionization chambers above and below a plastic Cerenkov counter. The energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 at very high energies where they are rare and thus need the large area x time are measured. The measurements of the Danish-French HEAO-3 experiment (Englemann,, et al., 1983) are extended to higher energies, using the relativistic rise of ionization signal as a measure of energy. Source abundances for Ar and Ca were determined

    Spallation dominated propagation of Heavy Cosmic Rays and the Local Interstellar Medium (LISM)

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    Measurements of ultra heavy nuclei at GeV/n energies in the galactic cosmic radiation address the question of the sources (nucleosynthetic s- and r-processes). As such, the determination of CR source abundances is a promising way to discriminate between existing nucleosynthesis models. For primary species (nuclei present and accelerated at sources), it is generally assumed that the relative propagated abundances, if they are close in mass, are not too different from their relative source abundances. Besides, the range of the correction factor associated to propagation has been estimated in weighted slab models only. Heavy CRs that are detected near Earth were accelerated from regions that are closer to us than were the light nuclei. Hence, the geometry of sources in the Solar neighbourhood, and as equally important, the geometry of gas in the same region, must be taken into account. In this paper, a two zone diffusion model is used, and as was previously investigated for radioactive species, we report here on the impact of the local interstellar medium (LISM) feature (under-dense medium over a scale ~100 pc) on primary and secondary stable nuclei propagated abundances. Going down to Fe nuclei, the connection between heavy and light abundances is also inspected. A general trend is found that decreases the UHCR source abundances relative to the HCR ones. This could have an impact on the level of r-process required to reproduce the data.Comment: 12 pages, 9 figures, accepted by A&A. Comparison with truncated weighted slab and discussion added. Figure 8 modified. New appendix on truncated weighted slab techniqu

    Energy Spectra of Elements with 18 ≤ Z ≤ 28 Between 10 and 300 GeV/amu

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    The HEAO-3 Heavy Nuclei Experiment (Binns, et al., 1981) is composed of ionization chambers above and below a plastic Cherenkov counter. We have measured the energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 at very high energies where they are rare and thus need the large area x time of this experiment. We extend the measurements of the Danish French HEAO-3 experiment (Englemann, et al., 19S3) to higher energies, using the relativistic rise of ionization signal as a measure of energy, and determine source abundances for Ar and Ca
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