54 research outputs found
Rational design of biosafe crop resistance to a range of nematodes using RNA interference
Double stranded RNA (dsRNA) molecules targeting two genes have been identified that suppress economically important parasitic nematode species of banana. Proteasomal Alpha Subunit 4 (pas-4) and Actin-4 (act-4) were identified from a survey of sequence databases and cloned sequences for genes conserved across four pests of banana, Radopholus similis, Pratylenchus coffeae, Meloidogyne incognita and Helicotylenchus multicinctus. These four species were targeted with dsRNAs containing exact 21 nucleotide matches to the conserved regions. Potential off-target effects were limited by comparison to Caenorhabditis, Drosophila, rat, rice and Arabidopsis genomes. In vitro act-4 dsRNA treatment of R. similis suppressed target gene expression by 2.3 fold, nematode locomotion by 66 ± 4% and nematode multiplication on carrot discs by 49 ± 5%. The best transgenic carrot hairy root lines expressing act-4 or pas-4 dsRNA reduced transcript message abundance of target genes in R. similis by 7.9 fold and 4 fold and nematode multiplication by 94 ± 2% and 69 ± 3%, respectively. The same act-4 and pas-4 lines reduced P. coffeae target transcripts by 1.7 and 2 fold and multiplication by 50 ± 6% and 73 ± 8%. Multiplication of M. incognita on the pas-4 lines was reduced by 97 ± 1% and 99 ± 1% while target transcript abundance was suppressed 4.9 and 5.6 fold. There was no detectable RNAi effect on non-target nematodes exposed to dsRNAs targeting parasitic nematodes. This work defines a framework for development of a range of non-protein defences to provide broad resistance to pests and pathogens of crops
Eureka and beyond: mining's impact on African urbanisation
This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-statesâ urbanisation trends have shown considerable variation over the past half century. The current surge in ânewâ mining countries and the slow-down in âoldâ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)
The NuSTAR Extragalactic Survey: A First Sensitive Look at the High-energy Cosmic X-Ray Background Population
We report on the first 10 identifications of sources serendipitously detected by the Nuclear Spectroscopic Telescope Array (NuSTAR) to provide the first sensitive census of the cosmic X-ray background source population at gsim 10 keV. We find that these NuSTAR-detected sources are â100 times fainter than those previously detected at gsim 10 keV and have a broad range in redshift and luminosity (z = 0.020-2.923 and L 10-40 keV â 4 Ă 1041-5 Ă 1045 erg sâ1); the median redshift and luminosity are z â 0.7 and L 10-40 keV â 3 Ă 1044 erg sâ1, respectively. We characterize these sources on the basis of broad-band â0.5-32 keV spectroscopy, optical spectroscopy, and broad-band ultraviolet-to-mid-infrared spectral energy distribution analyses. We find that the dominant source population is quasars with L 10-40 keV > 1044 erg sâ1, of which â50% are obscured with N H gsim 1022 cmâ2. However, none of the 10 NuSTAR sources are Compton thick (N H gsim 1024 cmâ2) and we place a 90% confidence upper limit on the fraction of Compton-thick quasars (L 10-40 keV > 1044 erg sâ1) selected at gsim 10 keV of lsim 33% over the redshift range z = 0.5-1.1. We jointly fitted the rest-frame â10-40 keV data for all of the non-beamed sources with L 10-40 keV > 1043 erg sâ1 to constrain the average strength of reflection; we find R < 1.4 for Î = 1.8, broadly consistent with that found for local active galactic nuclei (AGNs) observed at gsim 10 keV. We also constrain the host-galaxy masses and find a median stellar mass of â1011 M â, a factor â5 times higher than the median stellar mass of nearby high-energy selected AGNs, which may be at least partially driven by the order of magnitude higher X-ray luminosities of the NuSTAR sources. Within the low source-statistic limitations of our study, our results suggest that the overall properties of the NuSTAR sources are broadly similar to those of nearby high-energy selected AGNs but scaled up in luminosity and mass
Tides in colliding galaxies
Long tails and streams of stars are the most noticeable upshots of galaxy
collisions. Their origin as gravitational, tidal, disturbances has however been
recognized only less than fifty years ago and more than ten years after their
first observations. This Review describes how the idea of galactic tides
emerged, in particular thanks to the advances in numerical simulations, from
the first ones that included tens of particles to the most sophisticated ones
with tens of millions of them and state-of-the-art hydrodynamical
prescriptions. Theoretical aspects pertaining to the formation of tidal tails
are then presented. The third part of the review turns to observations and
underlines the need for collecting deep multi-wavelength data to tackle the
variety of physical processes exhibited by collisional debris. Tidal tails are
not just stellar structures, but turn out to contain all the components usually
found in galactic disks, in particular atomic / molecular gas and dust. They
host star-forming complexes and are able to form star-clusters or even
second-generation dwarf galaxies. The final part of the review discusses what
tidal tails can tell us (or not) about the structure and content of present-day
galaxies, including their dark components, and explains how tidal tails may be
used to probe the past evolution of galaxies and their mass assembly history.
On-going deep wide-field surveys disclose many new low-surface brightness
structures in the nearby Universe, offering great opportunities for attempting
galactic archeology with tidal tails.Comment: 46 pages, 13 figures, Review to be published in "Tidal effects in
Astronomy and Astrophysics", Lecture Notes in Physics. Comments are most
welcom
Ground conditions in central Manchester and Salford : the use of the 3D geoscientific model as a basis for decision support in the built environment
In the urban environment, site investigation studies provide
a wealth of information about the ground conditions of the
shallow subsurface. However, from the developersâ
perspective, there is generally little incentive to integrate
this information beyond the boundaries of the development
site. By taking a more holistic view and combining
knowledge of the near-surface geology with information on
former land use and the groundwater regime across a wider
area, it is possible to predict geological scenarios that may
better inform ground investigation and reclamation
strategies.
As part of its urban research programme, the British
Geological Survey has integrated its data holdings across
75 km2 of central Manchester and Salford. The information
has been used to develop an integrated 3D model of the
shallow subsurface. By exporting the elements of the model
to a Geographical Information System (GIS), there is the
capability to produce on demand bespoke maps, crosssections
and other visualisation aids, relevant to regional
planning and site appraisal. The value of such a system is
illustrated by reference to five topic areas (geology,
geotechnical engineering, hydrogeology, geochemistry and
land use). A series of thematic maps illustrates the range of
outputs.
The approach provides a means of identifying potential
problems and opportunities at an early stage in any proposed
development and, if implemented over a wider area, it could
assist in designing site investigation strategies and reduce
costs by ensuring a more focused approach to development
planning
Integrating modelling of geoscience information to support sustainable urban planning
The provision of reliable and up-to-date geoscientific information for the urban environment has assumed increasing importance in recent years as legislative changes have forced developers, planning authorities and regulators to consider more fully the implications and impact on the environment of large-scale development initiatives. To comply with the principles of sustainable development, developers are increasingly required to demonstrate that proposals are based on the best possible scientific information and analysis of risk. Nowhere is this more relevant than in the context of urban regeneration, where planning policy guidance gives priority to re-use of previously developed (brownfield) land. In England, brownfield sites, suitable for re-development, cover an area equivalent to half the size of London
Geology of the Pattingham area 1:10 000 sheet SO 89 NW; part of 1:50 000 sheet 153 (Wolverhampton) and 167 (Dudley)
SIGLEAvailable from British Library Document Supply Centre-DSC:8714.105(98/54) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Geology of the Dudley district : a brief explanation of the geological map sheet 167 Dudley
This Sheet Explanation provides a summary
of the geology of the district covered by the
geological 1:50 000 Series Sheet 167 Dudley
published as a bedrock and superficial
edition in 2012.
T he district lies in the counties of Shropshire,
Worcestershire, Staffordshire and the metropolitan
district of the West Midlands. The
main population centres are in the east of
the district, within the Black Country conurbation
that includes Bilston, Wednesbury,
Sedgley, Tipton, Dudley, Brierley Hill,
Kingswinford, Halesowen and Stourbridge.
Scattered villages and the town of Bridgnorth
lie in the west. The western and central parts
of the district comprise mainly farmland and
woodland, including the northern part of the
Wyre Forest. The elevation of the district is
typically in excess of 75 m above OD, with
the highest point within the district, at 315 m
above OD, in the Clent Hills in the south-east.
The district is drained by the rivers Severn
and Stour, which flow from north to south
across the western and central parts of the
district, respectively
The limestone and dolomite resources of the country north and west of Ashbourne, Derbyshire Description of 1/25.000 sheet SK 51 and parts of 04, 05 and 14
15.25LD:5776.72(IGS-MAR--129) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
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