1,009 research outputs found

    Evaluation of oilseed rape seed yield losses caused by Leptosphaeria biglobosa in central China

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    This document is the Accepted Manuscript version of the following article: Xiang Cai, Yongju Huang, Daohong Jiang, Bruce D. L. Fitt, Guoqing Li, and Long Yang, "Evaluation of oilseed rape seed yield losses caused by Leptosphaeria biglobosa in central China", European Journal of Plant Pathology, first published 9 June 2017. Under embargo. Embargo end date: 9 June 2018. The final publication is available at Springer via: http://dx.doi.org/10.1007/s10658-017-1266-x.Phoma stem canker of oilseed rape (Brassica napus), caused by Leptosphaeria maculans/L. biglobosa is a globally important disease. Severe phoma stem canker symptoms have been observed on winter oilseed rape in China but the seed yield loss caused by this disease remains unknown. In May 2012 and May 2013, 17 and 13 crops were surveyed, respectively, in seven counties of Hubei Province, central China. Stems with phoma stem canker disease symptoms were sampled for pathogen isolation and identification. Only L. biglobosa was identified by culture morphology and species-specific PCR; no L. maculans was found. To evaluate the yield losses, yield components (number of branches per plant, number of pods per plant, 1000-seed weight, number of seeds per pod) were assessed on healthy and diseased plants sampled from crops in four counties and on plants from inoculated pot experiments (plants of three cultivars were inoculated at the green bud stage by injecting L. biglobosa conidia into the stem between the first and second leaf scars). Results of the field surveys showed that diseased plants had 14–61% less branches and 32–83% less pods than healthy plants, respectively. The estimated seed yield loss varied from 10% to 21% and from 13% to 37% in 2012 and 2013, respectively. In the pot experiments, there were no differences in numbers of branches or pods but there were differences in number of seeds per pod between inoculated and control plants. For the three cultivars tested, the inoculated plants had yield losses of 29–56% compared with the control. This study indicates that L. biglobosa could cause substantial seed yield loss in China.Peer reviewedFinal Accepted Versio

    Shetlands Islands field trip May 2014 : summary of results

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    This report provides a record of a field excursion to the Shetland Islands in May 2014 to investigate sediments deposited from tsunamis generated from submarine landslides mainly located off the coast of Norway. The research was funded under a NERC Consortium Grant for a project entitled ‘Will climate change in the Arctic increase the landslide-tsunami risk to the UK?’ It was part of Work Block 2 (WB2): ‘What is the timing of tsunami deposits on the UK coastline, and how is it related to the age of major Arctic slides’? The best known and most studied tsunami from the Norwegian submarine landslides is the Storegga event dated at 8,200BP. Sediments deposited from this tsunami are commonly found along the west coast of Norway, east coast of mainland Scotland, and also on the Shetland and Faeroe islands. However, there are other landslides off of Norway for which no associated tsunami has been identified, which poses the question as to whether these events did not generate a tsunami or whether the evidence for a tsunami has not yet been found. Although evidence for seabed slumping off Norway was first discovered in the 1950’s (Holtedahl, 1955, 1971) and the scale and morphology of a massive submarine landslide, subsequently termed Storegga, mapped in the 1970’s (Bugge, 1983), it was not until 1985 that an associated tsunami was first proposed (Svendsen, 1985). The first supporting sedimentary evidence of the tsunami was first identified on mainland Scotland in 1988 (Dawson et al., 1988) then, subsequently, similar sediments were identified on the Shetland Islands (Smith, 1993a). The Storegga Slide has been dated to 8,150BP (Haflidason et al., 2005), however more recent research on the deposits on the Shetlands suggests that some may not all be from Storegga, because 14C age dating gives younger ages of ~5,000 and 1,500 cal yr BP (Bondevik et al., 2005). A major challenge posed by the ages of these younger dates is that they are confined to the Shetlands; there is no indication of these younger tsunamis on mainland Scotland. If the dating is correct and the sediments are indeed from tsunamis, then the submarine landslides off Norway would be an unlikely source, so a local source seems most likely, but none has yet been identified. Alternatively a non-tsunami source for the sediments may explain their presence. The objectives of WB2 therefore are to investigate the tsunami deposits on Shetland that post-date the Storegga Slide, to validate their ages and, if possible, identify possible source locations of the submarine landslides that generated the tsunamis. On Shetland research on tsunami sediments was mainly based on evidence from coastal exposures around Sullom Voe where tsunami sands are dated as coeval with Storegga. The younger sands are mainly preserved in lake cores at locations on Shetland Mainland (Bondevik et al., 2005) where those of 5,000 BP overlie sands of Storegga age at 8,200 years BP age. At coastal sites along Basta Voe on Yell and at a mainland site at Dury Voe very young age dates of ~1,500 BP suggest an additional and very recent, late Holocene event (Bondevik et al., 2005; Dawson et al, 2006). A preliminary field excursion to the Shetlands carried out in 2013 discovered possible new tsunami deposits preserved in peat on central Yell at Whale Firth, Mid Yell Voe and Kirkabister. Subsequent 14C age dating of these deposits resulted in a variety of ages, many much younger than that of Storegga. The 14C method is known to be subject to major uncertainties because of contamination, for example initial age dating in the 1990’s at sites around Sullom Voe returned ages of around 5,000 years BP, although these were subsequently rejected in favour of the earlier, 8,200 BP Storegga event. Thus, validating the ages of the deposits on Yell, prospectively from a number of deposits laid down successively at one site (thereby reducing the sole reliance on 14C dating) was critical in validating the presence of more than one tsunami event on Shetland. The objective of the 2014 field visit to the Shetlands, therefore, was to return to Yell and validate the preliminary results from 2013; revisiting the sites at Whale Firth, Mid Yell and Kirkabister and searching the coastlines of Unst, Fetlar, Yell and north Mainland for additional sites where tsunami sediments might be preserved. Just before the visit new 14C dates from Mid Yell from samples collected in 2013 confirmed the previous results from other locations that had given a wide range of ages; at Whale Firth a single date gave a ‘young’ age of ~5,000 years BP, a range of ages with the oldest at 8,200 years BP were returned from Mid Yell Voe. We first visited sites on north Mainland around Sullom Voe, as it was here that the first indications of the Storegga tsunami were identified on Shetland in 1992. The deposits are classic as they contain rip-up clasts characteristic of tsunami deposits elsewhere. We then visited the sites at Basta Voe, Whale Firth, Mid Yell and Kirkabister. We carried out reconnaissance surveys on Unst, Fetlar, Yell and north Mainland. Preliminary results: 1. The new evidence supports the presence of tsunami sediments on Yell at Mid Yell Voe and Whale Firth, but the age of these sediments requires further research to confirm previous dating and their possible sources, 2. The youngest dated sediments (~1,500 BP) at Vasta Voe are most likely from a tsunami, but their limited areal extent suggests a local source, as yet undetermined, 3. The presence of three events at Mid Yell Voe based on surveys in 2013 was not confirmed, 4. The similarity of the deposits on Mid Yell with those around Sullom Voe on Mainland are suggestive of a similar source, 5. The wide range of the preliminary age dating at the Mid Yell sites (Whale Firth and Mid Yell Voe) is analogous to the early age dating of coastal deposits around Sullom Voe, suggesting the possibility of contamination of the peat material dated, 6. Whereas the 5,500BP event is identified in lake cores, no strongly supportive evidence for sands of this age were identified in the coastal sections, 7. Of the proposed three tsunami events proposed for Shetland only one, Storegga, has a confirmed source, 8. Further analysis of the peat stratigraphy at the coastal sites, reflects vegetation changes over the past ~8,000 years related to climate change, and these could be used to provide a broader context for the 14C age dating that may resolve the present dating issues, 9. Newly discovered sediments at Kirkabister require further research to determine their origin, 10. The origin(s) of the laminated deposits at Whale Firth, Mid Yell and Vatsetter is/are uncertain, but they are probably not from a tsunami, 11. No additional coastal exposures of peat with tsunami sands were located during the reconnaissance surveys on Mainland, Yell, Unst and Fetlar. Postscript; Immediately after this report was finalised, age dating of peat sections at Whale Firth and Mid Yell Voe confirmed that the sands preserved in the woody peat here are of Storegga age, ~8,200 cal yr BP

    A Comment on "The Far Future of Exoplanet Direct Characterization" - the Case for Interstellar Space Probes

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    Following on from ideas presented in a recent paper by Schneider et al. (2010) on "The Far Future of Exoplanet Direct Characterization", I argue that they have exaggerated the technical obstacles to performing such 'direct characterization' by means of fast (order 0.1c) interstellar space probes. A brief summary of rapid interstellar spaceflight concepts that may be found in the literature is presented. I argue that the presence of interstellar dust grains, while certainly something which will need to be allowed for in interstellar vehicle design, is unlikely to be the kind of 'show stopper' suggested by Schneider et al. Astrobiology as a discipline would be a major beneficiary of developing an interstellar spaceflight capability, albeit in the longer term, and I argue that astrobiologists should keep an open mind to the possibilities.Comment: Accepted for publication in Astrobiolog

    Programming the assembly of carboxylic acid-functionalised hybrid polyoxometalates

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    We report here the straightforward synthesis and characterisation of a series Anderson-type hybrid polyoxometalates in high yield, functionalised with carboxylic acid following the reaction of anhydride precursors with the starting hybrid cluster ([n-N(C4H9)4]3[MnMo6O18((OCH2)3CNH2)2]). Seven new structures have been obtained, five of which have acid-terminated ligands. Six of these structures have been isolated with a yield higher than 80% with high purity. This reaction is limited by the bulkiness of the anhydride used; this effect can be employed to selectively synthesise one isomer out of three other possibilities. The acid groups and aromatic platforms attached to the clusters can act as building tools to bridge several length scales and engineer molecular packing within the crystal structure. The presence of acids should also change the hydrophilicity of the clusters, and therefore the way they interact with hydrophilic surfaces. We also show a potential relationship between the acid group interaction in the packing diagram and the cluster’s tendency to interact with a hydrophilic surface. In addition to reporting a derived synthetic path to new acid-terminated Mn-Anderson-type hybrids, we describe here a new way to program self-assembly motifs of these compounds in the crystal structure and at interfaces

    Stability of the Scalar Potential and Symmetry Breaking in the Economical 3-3-1 Model

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    A detailed study of the criteria for stability of the scalar potential and the proper electroweak symmetry breaking pattern in the economical 3-3-1 model, is presented. For the analysis we use, and improve, a method previously developed to study the scalar potential in the two-Higgs-doublet extension of the standard model. A new theorem related to the stability of the potential is stated. As a consequence of this study, the consistency of the economical 3-3-1 model emerges.Comment: to be published in EPJ C, 13 page

    The effect of education on oral health students' attitudes in Australia and New Zealand

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    Objective: The aim of this study was to evaluate the oral health attitudes and behavior of students in the oral health curriculum in Australia and New Zealand. Materials and Methods: The Hiroshima University - Dental Behavioral Inventory was administered to students in the first (year 1) and final years (year 3) of the oral health curriculum at Charles Sturt University in Australia and the University of Otago in New Zealand. A total of fifty-two year 1 students and forty-five year 3 students completed English version of the questionnaire in 2013. The responses were statistically analyzed by Fisher's exact tests and exact logistic regression models. Results: The responses of students in years 1 and 3 differed significantly for "I worry about the color of my teeth" at Charles Sturt University and at the University Otago, for "I think my teeth are getting worse despite my daily brushing," "I put off going to the dentist until I have a toothache," and "I don't feel I've brushed well unless I brush with strong strokes." The estimated odds ratios from the exact logistic regression models showed that year 1 students were more likely to agree with above-mentioned four questions. Conclusions: Oral Health students who had been educated in a 3-year oral health curriculum in Australia and New Zealand had more positive attitudes and behaviors related oral health than did students at the beginning of their curriculum

    The Landau Pole and Z′Z^{\prime} decays in the 331 bilepton model

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    We calculate the decay widths and branching ratios of the extra neutral boson Z′Z^{\prime} predicted by the 331 bilepton model in the framework of two different particle contents. These calculations are performed taken into account oblique radiative corrections, and Flavor Changing Neutral Currents (FCNC) under the ansatz of Matsuda as a texture for the quark mass matrices. Contributions of the order of 10−1−10−210^{-1}-10^{-2} are obtained in the branching ratios, and partial widths about one order of magnitude bigger in relation with other non- and bilepton models are also obtained. A Landau-like pole arise at 3.5 TeV considering the full particle content of the minimal model (MM), where the exotic sector is considered as a degenerated spectrum at 3 TeV scale. The Landau pole problem can be avoid at the TeV scales if a new leptonic content running below the threshold at % 3 TeV is implemented as suggested by other authors.Comment: 20 pages, 5 figures, LaTeX2
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