2,314 research outputs found
Papers from the British Academy Lucy to Language: Archaeology of the Social Brain. Seminar Series on Palaeolithic Visual Display.
No full textContentsThe Importance of Conveying Visual Information in Acheulean Society. The Background to the Visual Display HypothesisDr John McNabb, Centre for the Archaeology of Human Origins (CAHO), Department of Archaeology, University of Southampton, Southampton, Hampshire, SO17 1BF, [email protected] Identity Model: a theory to access visual display and hominin cognition within the PalaeolithicJames Cole, Centre for the Archaeology of Human Origins (CAHO), Department of Archaeology, University of Southampton, Southampton, Hampshire, SO17 1BF, [email protected] Tool Production, Neural Integration and the Social BrainDerek Hodgson, Department of Archaeology, University of York, York, [email protected] Phylogeny and Ontogeny in Hominin Brain EvolutionFiona Coward, Department of Geography Royal Holloway University of London, Egham, Surrey, TW20 0EX, [email protected] Grove, School of Archaeology, Classics and Egyptology, University of Liverpool, G.09 HartleyBuilding, Brownlow Street, Liverpool L69 3GS, [email protected]
Climate change and ocean acidification impacts on lower trophic levels and the export of organic carbon to the deep ocean
No full textMost future projections forecast significant and ongoing climate change during the 21st century, but with the severity of impacts dependent on efforts to restrain or reorganise human activity to limit carbon dioxide (CO2) emissions. A major sink for atmospheric CO2, and a key source of biological resources, the World Ocean is widely anticipated to undergo profound physical and – via ocean acidification – chemical changes as direct and indirect results of these emissions. Given strong biophysical coupling, the marine biota is also expected to experience strong changes in response to this anthropogenic forcing. Here we examine the large-scale response of ocean biogeochemistry to climate and acidification impacts during the 21st century for Representative Concentration Pathways (RCPs) 2.6 and 8.5 using an intermediate complexity global ecosystem model, MEDUSA-2.0. The primary impact of future change lies in stratification-led declines in the availability of key nutrients in surface waters, which in turn leads to a global decrease (1990s vs. 2090s) in ocean productivity (?6.3%). This impact has knock-on consequences for the abundance of the low trophic level biogeochemical actors modelled by MEDUSA-2.0 (?5.8%), and these would be expected to similarly impact higher trophic level elements such as fisheries. Related impacts are found in the flux of organic material to seafloor communities (?40.7% at 1000 m), and in the volume of ocean suboxic zones (+12.5%). A sensitivity analysis removing an acidification feedback on calcification finds that change in this process significantly impacts benthic communities, suggesting that a~better understanding of the OA-sensitivity of calcifying organisms, and their role in ballasting sinking organic carbon, may significantly improve forecasting of these ecosystems. For all processes, there is geographical variability in change – for instance, productivity declines ?21% in the Atlantic and increases +59% in the Arctic – and changes are much more pronounced under RCP 8.5 than the RCP 2.6 scenario
Eddies around Madagascar - the retroflection re-considered
No full textThe Agulhas Current with its retroflection and attendant eddy-shedding is the cause of some of the greatest mesoscale variability in the ocean. This paper considers the area to the south and east of Madagascar, which provides some of the source waters of the Agulhas Current, and examines the propagating sea surface height signals in altimetry and output from a numerical model, OCCAM. Both show bands of variability along the axis of the East Madagascar Current (EMC) and along a zonal band near 25°S. Sequences of images plus associated temperature data suggest that a number of westward-propagating eddies are present in this zonal band. The paper then focuses on the region to the south of the island, where ocean colour and infra-red imagery are evocative of an East Madagascar Retroflection. The synthesis of data analysed in this paper, however, show that remotely observed features in this area can be explained by anticyclonic eddies moving westward through the region, and this explanation is consistent with numerical model output and the trajectories of drifting buoys
Mozambique Channel Eddies in GCMs: A question of resolution and slippage
No full textHydrographic observations in the 21st century have shown that the flow within the MozambiqueChannel is best described by a series of large poleward-propagating anticyclonic eddies, rather than, aspreviously thought, a continuous intense western boundary current. The portrayal of this region in various runs of the NEMO 75-level model is found to vary between those two descriptions depending upon the resolution used and the implementation of the model's lateral boundary conditions. In a comparison of 1/4 ? resolution runs, the change of these conditions from free-slip to no-slip leads to the mean southward flow moving further offshore, with greater variability in the zonal and meridional velocities as the flow organises itself into eddies, and a reduction in total transport. If a realization of a model is unable to get these aspects of the physical flow correct, then this will significantly reduce its ability to show a realistic biological signal or long-term response to climate change. Further south, beyond Durban, the application of no-slip conditions similarly causes the mean Agulhas Current to lie further offshore, making it much more able to simulate Natal Pulses.<br/
The Swift gamma-ray burst redshift distribution: selection biases and optical brightness evolution at high z?
No full textWe employ realistic constraints on astrophysical and instrumental selection effects to model the gamma-ray burst (GRB) redshift distribution using Swift triggered redshift samples acquired from optical afterglows and The Optically Unbiased GRB Host survey. Models for the Malmquist bias, redshift desert, and the fraction of afterglows missing because of host galaxy dust extinction are used to show how the `true' GRB redshift distribution is distorted to its presently observed biased distribution. We also investigate another selection effect arising from a correlation between Eiso and Lopt. The analysis, which accounts for the missing fraction of redshifts in the two data subsets, shows that a combination of selection effects (both instrumental and astrophysical) can describe the observed GRB redshift distribution. Furthermore, the observed distribution is compatible with a GRB rate evolution that tracks the global star formation rate, although the rate at high z cannot be constrained with confidence. Taking optical selection effects into account, it may not be necessary to invoke high-energy GRB luminosity evolution with redshift to explain the observed GRB rate at high z
Serum HE4 as a prognostic marker in endometrial cancer - a population based study
No full textAbstract not availableDonal J. Brennan, Andreas Hackethal, Alex M. Metcalf, Jermaine Coward, Kaltin Ferguson, Martin K. Oehler, Michael A. Quinn, Monika Janda, Yee Leung, Michael Freemantle, ANECS Group, Penelope M. Webb, Amanda B. Spurdle, Andreas Obermai
Iron and titanium amino-phenolate complexes in controlled alkene polymerisation
No full textTransition metals have long been used as both catalysts and mediators in the polymerisation
of many monomers. This thesis explores the use of iron and titanium amino-phenolate
complexes as mediators in the polymerisation of alkene monomers.
Initial work focused on understanding the fundamental mechanisms behind the
organometallic-mediated radical polymerisation (OMRP) of styrene, methyl methacrylate
(MMA) and vinyl acetate using a novel and fully characterised tert-butyl substituted aminebis(phenolate) iron(II) complex. A range of temperatures and conditions were explored to
elucidate the equilibrium between propagation and termination reactions in the
polymerisation. It was found that in the polymerisation of MMA, propagation was favoured
at low conversion with good control and reasonable dispersities. Mechanistic studies suggest
that propagation proceeds through a reversible-termination OMRP mechanism. At higher
conversions, irreversible termination reactions become dominant. The polymerisation
temperature significantly affects the nature of termination, dictating whether termination is
either bimolecular or via catalytic chain transfer (CCT). The polymerisation of styrene shows
well-controlled behaviour with dispersities as low as 1.27, which is the first time this has been
achieved for iron-mediated OMRP. The use of alternative initiation methods, such as
macroinitiators and photoinitiators, is also discussed.
A family of titanium(III) amino-phenolate complexes were used as mediators in the
polymerisation of methacrylates. Well-controlled polymerisations were achieved, with linear
first-order kinetics and dispersities as low as 1.09. The nature of the substituents on the
ligand greatly affects the tacticity of the resultant polymer, with large bulky groups having a
more significant effect in promoting isotactic polymer. Detailed experimental and
computational studies suggest that the polymerisation mechanism is not radical or ionic, but
instead proceeds through a coordinating-type mechanism. This mechanism is suggested to
be bimetallic, involving a titanium(IV)-enolate complex and an MMA-coordinated
titanium(III) species, with polymerisation propagating via a group transfer mechanism, which
is rarely exhibited in transition metals. This also likely represents the first example of the
initiation of a coordination polymerisation with a conventional azo initiator, without the need
for pyrophoric or expensive activators
KCNQ/M currents in sensory neurons: Significance for pain therapy
No full textNeuronal hyperexcitability is a feature of epilepsy and both inflammatory and neuropathic pain. M currents [I-K(M)] play a key role in regulating neuronal excitability, and mutations in neuronal KCNQ2/3 subunits, the molecular correlates of I-K(M), have previously been linked to benign familial neonatal epilepsy. Here, we demonstrate that KCNQ/M channels are also present in nociceptive sensory systems. I-K(M) was identified, on the basis of biophysical and pharmacological properties, in cultured neurons isolated from dorsal root ganglia (DRGs) from 17-d-old rats. Currents were inhibited by the M-channel blockers linopirdine (IC50, 2.1 muM) and XE991 (IC50, 0.26 muM) and enhanced by retigabine (10 muM). The expression of neuronal KCNQ subunits in DRG neurons was confirmed using reverse transcription-PCR and single-cell PCR analysis and by immunofluorescence. Retigabine, applied to the dorsal spinal cord, inhibited C and Adelta fiber-mediated responses of dorsal horn neurons evoked by natural or electrical afferent stimulation and the progressive "windup" discharge with repetitive stimulation in normal rats and in rats subjected to spinal nerve ligation. Retigabine also inhibited responses to intrapaw application of carrageenan in a rat model of chronic pain; this was reversed by XE991. It is suggested that I-K(M) plays a key role in controlling the excitability of nociceptors and may represent a novel analgesic target
Acceleration of the Antarctic Circumpolar Current by Wind Stress along the Coast of Antarctica
No full textThe influence of wind forcing on variability of the Antarctic Circumpolar Current (ACC) is investigated using a series of eddy-permitting ocean–sea ice models. At interannual and decadal time scales the ACC transport is sensitive to both the mean strength of westerly winds along the ACC circumpolar path, consistent with zonal momentum balance theories, and sensitive to the wind stresses along the coast of Antarctica, consistent with the “free mode” theory of Hughes et al. A linear combination of the two factors explains differences in ACC transport across 11 regional quasi-equilibrium experiments. Repeated single-year global experiments show that the ACC can be robustly accelerated by both processes. Across an ensemble of simulations with realistic forcing over the second half of the twentieth century, interannual ACC transport variability owing to the free-mode mechanism exceeds that due to the zonal momentum balance mechanism by a factor of between 3.5 and 5 to one. While the ACC transport may not accelerate significantly owing to projected increases in along-ACC winds in future decades, significant changes in transport could still occur because of changes in the stress along the coast of Antarctica
Status of the Australian consortium for interferometric gravitational astronomy
No full textCopyright © Institute of Physics and IOP Publishing Limited 2006We report the status of research and development being undertaken by the members of the Australian Consortium for Interferometric Gravitational Astronomy.D E McClelland, S M Scott, M B Gray, A C Searle, S Goßler, B J J Slagmolen, J Dickson, J H Chow, G de Vine, K McKenzie, C M Mow-Lowry, A Moylan, D S Rabeling, B S Sheard, J Cumpston, K Wette, D G Blair, L Ju, R Burman, D Coward, C Zhao, P Barriga, E Chin, J Degallaix, Y Fan, S Gras, E Howell, B Lee, S Schediwy, Z Yan, J Munch, P J Veitch, D Mudge, A Brooks and D Hoske
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