841 research outputs found
Heart rot of Australian pineapples caused by Dickeya zeae
Pineapple plants (hybrid MD2) with bacterial heart rot were detected in a commercial plantation at Glasshouse Mountains, Queensland, in November 2015. The bacterial strain BRIP64263 isolated from infected tissue was shown to be a Gram negative soft-rotting bacterium capable of growth at 41 ºC, and based on its culture properties was provisionally identified as Dickeya. This strain was compared with other putative Dickeya strains affecting banana (BRIP64262) and potato (BRIP29490). Sequence analysis of the recombinase A genes of the pineapple strain placed it in phylotype I of D. zeae, whereas the banana strain was placed in phylotype II. This was confirmed by sequence comparisons for the phosphofructose kinase, RNA polymerase and aconitase genes which showed that the pineapple strain BRIP64263 is distinct from other strains that infect pineapples and other hosts in Australia and overseas. Furthermore, phylogenetic analysis of the replication initiation factor gene showed that strains affecting pineapples were distributed among both phylotypes of D. zeae, indicating multiple acquisitions or opportunistic infections of pineapple from this group of pathogens. The potato isolate, BRIP29490, was shown to be Rahnella aquatica, and is not likely to be pathogenic. It is not known whether the new isolate represents an incursion or whether it has long been associated with pineapples in Australia. Further study is required to determine the epidemiological characteristics of this strain, and what threat it poses to Australian pineapple production
Heart rot of Australian pineapples caused by Dickeya zeae
Pineapple plants (hybrid MD2) with bacterial heart rot were detected in a commercial plantation at Glasshouse Mountains, Queensland, in November 2015. The bacterial strain BRIP64263 isolated from infected tissue was shown to be a Gram negative soft-rotting bacterium capable of growth at 41 ºC, and based on its culture properties was provisionally identified as Dickeya. This strain was compared with other putative Dickeya strains affecting banana (BRIP64262) and potato (BRIP29490). Sequence analysis of the recombinase A genes of the pineapple strain placed it in phylotype I of D. zeae, whereas the banana strain was placed in phylotype II. This was confirmed by sequence comparisons for the phosphofructose kinase, RNA polymerase and aconitase genes which showed that the pineapple strain BRIP64263 is distinct from other strains that infect pineapples and other hosts in Australia and overseas. Furthermore, phylogenetic analysis of the replication initiation factor gene showed that strains affecting pineapples were distributed among both phylotypes of D. zeae, indicating multiple acquisitions or opportunistic infections of pineapple from this group of pathogens. The potato isolate, BRIP29490, was shown to be Rahnella aquatica, and is not likely to be pathogenic. It is not known whether the new isolate represents an incursion or whether it has long been associated with pineapples in Australia. Further study is required to determine the epidemiological characteristics of this strain, and what threat it poses to Australian pineapple production
The ELAIS deep X-ray survey - I. Chandra source catalogue and first results
We present an analysis of two deep (75 ks) Chandra observations of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) fields N1 and N2 as the first results from the ELAIS deep X-ray survey. This survey is being conducted in well-studied regions with extensive multiwavelength coverage. Here we present the Chandra source catalogues along with an analysis of source counts, hardness ratios and optical classifications. A total of 233 X-ray point sources are detected in addition to two soft extended sources, which are found to be associated with galaxy clusters. An overdensity of sources is found in N1 with 30 per cent more sources than N2, which we attribute to large-scale structure. A similar variance is seen between other deep Chandra surveys. The source count statistics reveal an increasing fraction of hard sources at fainter fluxes. The number of galaxy-like counterparts also increases dramatically towards fainter fluxes, consistent with the emergence of a large population of obscured sources
The ELAIS Deep X-ray Survey
We present initial follow-up results of the ELAIS Deep X-ray Survey which is
being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray
sources are detected in our two 75 ks ACIS-I observations in the well-studied
ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to
R=26 with a median magnitude of R=24. We show that objects which are unresolved
optically (i.e. quasars) follow a correlation between their optical and X-ray
fluxes, whereas galaxies do not. We also find that the quasars with fainter
optical counterparts have harder X-ray spectra, consistent with absorption at
both wavebands. Initial spectroscopic follow-up has revealed a large fraction
of high-luminosity Type 2 quasars. The prospects for studying the evolution of
the host galaxies of X-ray selected Type 2 AGN are considered.Comment: 9 pages, 5 figures, To appear in Proceedings of XXI Moriond
Conference: "Galaxy Clusters and the High Redshift Universe Observed in
X-rays", edited by D. Neumann, F.Durret, & J. Tran Thanh Va
The Journal of the Friends' Historical Society vol. 4 No. 4
1. Notices.
2. Notes and Queries.
3. An Unpublished Letter of Hannah Penn.
4. The Quaker Allusions in "The Diary of Samuel Pepys" II.
5. Presentations of Quakers in Episcopal Visitations, 1662-1679.
6. Attitude of Friends under Persecution.
7. Friends' Views Negatively and Positively Presented.
8. Laces made in Warwick Jail.
9. Priest Whitehead of Halton, Lancs.
10. Early Meetings in Nottinghamshire.
11. Editors' Notes.
12. Friends in Current Literature.
13. Early Collections.
14. Anecdotes of Robert and James Gray.
15. Whitby and Scarborough Register.
16. An Early Loan Fund.
17. Mission Work in Rossendale.
18. Index to Volume IV
The mineral clouds on HD209 458b and HD189 733b
This is the final version of the article. Available from the publisher via the DOI in this record.3D atmosphere model results are used to comparatively study the kinetic, nonequilibrium
cloud formation in the atmospheres of two example planets guided by
the giant gas planets HD 209 458b and HD 189 733b. Rather independently of hydrodynamic
model differences, our cloud modelling suggests that both planets are covered
in mineral clouds throughout the entire modelling domain. Both planets harbour chemically
complex clouds that are made of mineral particles that have a height-dependent
material composition and size. The remaining gas-phase element abundances strongly
effects the molecular abundances of the atmosphere in the cloud forming regions. Hydrocarbon
and cyanopolyyne molecules can be rather abundant in the inner, dense
part of the atmospheres of HD 189 733b and HD 209 458b. No one value for metallicity
and the C/O ratio can be used to describe an extrasolar planet. Our results concerning
the presence and location of water in relation to the clouds explain some of the
observed differences between the two planets. In HD 189 733b, strong water features
have been reported while such features are less strong for HD 209 458b. By considering
the location of the clouds in the two atmospheres, we see that obscuring clouds exist
high in the atmosphere of HD 209 458b, but much deeper in HD 189 733b. We further
conclude that the (self-imposed) degeneracy of cloud parameters in retrieval methods
can only be lifted if the cloud formation processes are accurately modelled in contrast
to prescribing them by independent parametersWe highlight financial support of the European Community
under the FP7 by the ERC starting grant 257431 and by an
ERC advanced grant 247060. JK acknowledges the Rosen
fellowship from the Brooklyn College New York, US. Some
of the calculations for this paper were performed on the
DIRAC Facility jointly funded by STFC, the Large Facilities
Capital Fund of BIS, and the University of Exeter
Large Variations in Volcanic Aerosol Forcing Efficiency Due to Eruption Source Parameters and Rapid Adjustments
The relationship between volcanic stratospheric aerosol optical depth (SAOD) and volcanic radiative forcing is key to quantify volcanic climate impacts. In their fifth assessment report, the Intergovernmental Panel on Climate Change used one scaling factor between volcanic SAOD and volcanic forcing based on climate model simulations of the 1991 Mt. Pinatubo eruption, which may not be appropriate for all eruptions. Using a large-ensemble of aerosol-chemistry-climate simulations of eruptions with different sulfur dioxide emissions, latitudes, emission altitudes and seasons, we find that the effective radiative forcing (ERF) is on average 20% less than the instantaneous radiative forcing, predominantly due to a positive shortwave cloud adjustment. In our model, the volcanic SAOD-ERF relationship is non-unique and varies widely depending on time since an eruption, eruption latitude and season due to differences in aerosol dispersion and incoming solar radiation. Our revised SAOD-ERF relationships suggest that volcanic forcing has been previously overestimated
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