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Search Results: 1 - 10 of 533285 matches for " P. M. King "
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The impact of earthquakes on fluids in the crust
G. C. P. King,R. M. Wood
Annals of Geophysics , 1994, DOI: 10.4401/ag-4147
Abstract: The character of the hydrological changes that follow major earthquakes has been investigated and found to be critically dependent on the style of fault displacement. In areas where fracture-flow in the crystalline crust communicates uninterrupted with the surface the most significant response is found to accompany major normal fault earthquakes. Increases in spring and river discharges peak a few days after the earthquake and typically excess flow is sustained for a period of 4 12 months. Rainfall equivalent discharges, have been found to ceed 100 mm close to the fault and remain above 10 mm at distances greater than 50 km. The total volume of water released in two M 7 normal fault earthquakes in the Western U.S.A. was 0.3-0.5 km3. In contrast, hydroIogical changes accompanying reverse fault earthquakes are either undetected or else involve falls in well-levels and spring-flows. The magnitude and distribution of the water-discharge for these events is compared with deformation models calibrated from seismic and geodetic information, and found to correlate with the crustal volume strain down to a depth of at least 5 km. Such relatively rapid drainage is only possible if the fluid was formerly contained in high aspect ratio fissures interconnected throughout much of the seismogenic upper crust. The rise and decay times of the discharge are shown to be critically dependent on crack widths, for which the characteristic or dominant cracks cannot be wider than 0.03 mm. These results suggest that fluid-filled cracks are ubiquitous throughout the brittle continental crust, and that these cracks open and close through the earthquake cycle. Seismohydraulic fluid flows have major implications for our understanding of the mechanical and chemical behaviour of crustal rocks, of the tectonic controls of fluid flow associated with petroleum migration, hydrothermal mineralisation and a significant hazard for underground waste disposal.
Can a bank crisis break your heart?
David Stuckler, Christopher M Meissner, Lawrence P King
Globalization and Health , 2008, DOI: 10.1186/1744-8603-4-1
Abstract: International, longitudinal multivariate regression analysis of cardiovascular disease mortality data from 1960 to 2002A system-wide banking crisis increases population heart disease mortality rates by 6.4% (95% CI: 2.5% to 10.2%, p < 0.01) in high income countries, after controlling for economic change, macroeconomic instability, and population age and social distribution. The estimated effect is nearly four times as large in low income countries.Banking crises are a significant determinant of short-term increases in heart disease mortality rates, and may have more severe consequences for developing countries.Fear of financial loss drives people to do irrational things. As the runs on Northern Rock banks in England took place, one could not help but wonder how people's trust in the financial system could have eroded so rapidly.1 Much worse, the spread of panic, in part propelled by media, appears to have turned what could have otherwise been a momentary blip on the financial scene into an economic policy debacle – ultimately leading to a reluctant intervention by the Bank of England and an historic guarantee by the chancellor of the exchequer of all Northern Rock deposits in the UK banking system. But the financial storm has not yet passed.2What might be the health implications if the Northern Rock episode develops further into a full-fledged banking crisis in England? To our knowledge, no study has evaluated the relationship between a banking crisis and mortality, even though such crises have occurred more than once every two years in developed countries in the past 30 years. As the current experiences suggest, banking crises impose considerable panic and stress on people and, in particular, on vulnerable older populations. Such acute mental distress has been shown to i) significantly raise heart rate and blood pressure, which may increase myocardial oxygen demand and disrupt vulnerable plaques, and ii) in atherosclerotic patients lead to primary reductions in myo
Potential Inbreeding in a Small Population of a Mass Flowering Species, Xanthorrhoea johnsonii (Xanthorrhoeaceae): Is Your Mother My Father?  [PDF]
Rachel King, Jacinta M. Zalucki
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.33036
Abstract: Xanthorrhoea johnsonii is a long lived slow growing perennial understorey species, that produces a large quantity of passively dispersed seed every 3 - 5 years. Reproductive maturity is not reached until 20 - 30 years of age. The temporal asynchrony of the flowering event in this population was analogous to geographic isolation through fragmentation. A small population of plants flowering in isolation provided the opportunity to examine outcrossing rates, genetic diversity and the paternity of progeny at a small spatial scale (0.2 ha). The geographic location and physical characteristics of the adult plants were recorded, and both adults and their seed were sampled for genetic analysis. Four microsatellite loci were screened for genetic diversity and spatial structure analysis. A population outcrossing rate was estimated, as well as the number of paternal parents required to resolve the progeny multilocus genotypes. High genetic diversity was found in both adults and progeny with an estimated 97% outcrossing rate. All maternal lines required several paternal contributors, with no evidence of dominant paternal genotypes. Pollen transfer occurred between both geographically close and distant plants.
Using VLBI Data to Investigate the Galaxy Structure in the Gravitationally Lensed System B1422+231
M. Bradac,P. Schneider,M. Steinmetz,M. Lombardi,L. King,R. Porcas
Physics , 2002,
Abstract: Gravitationally lensed systems with multiply imaged quasars are an excellent tool for studying the properties of distant galaxies. In particular, they provide the most accurate mass measures for the lensing galaxy. The system B1422+231 is a well studied example of a quadruply imaged quasar, with high-quality VLBI data available. Very accurate data on image positions, fluxes and deconvolved image sizes provide good constraints for lensing models. We discuss here the failure of smooth models in fitting the data. Since it is intuitively clear that the mass of a lens galaxy is not a smooth entity, we have investigated how deviation from a smooth model can influence lensing phenomena, especially the image flux ratios. To explore expectations about the level of substructure in galaxies and its influence on strong lensing, N-body simulations of a model galaxy are employed. By using the mass distribution of this model galaxy as a lens, synthetic data sets of different four image system configurations are generated. Their analysis can possibly provide evidence for the presence and strong influence of substructure in the primary lens galaxy.
B1422+231: The influence of mass substructure on strong lensing
M. Bradac,P. Schneider,M. Steinmetz,M. Lombardi,L. J. King,R. Porcas
Physics , 2001, DOI: 10.1051/0004-6361:20020559
Abstract: In this work we investigate the gravitationally lensed system B1422+231. High--quality VLBI image positions, fluxes and shapes as well as an optical HST lens galaxy position are used. First, two simple and smooth models for the lens galaxy are applied to fit observed image positions and fluxes; no even remotely acceptable model was found. Such models also do not accurately reproduce the image shapes. In order to fit the data successfully, mass substructure has to be added to the lens, and its level is estimated. To explore expectations about the level of substructure in galaxies and its influence on strong lensing, N-body simulation results of a model galaxy are employed. By using the mass distribution of this model galaxy as a lens, synthetic data sets of different four image system configurations are generated and simple lens models are again applied to fit them. The difficulties in fitting these lens systems turn out to be similar to the case of some real gravitationally lensed systems, thus possibly providing evidence for the presence and strong influence of substructure in the primary lens galaxy.
Upregulation of ADAM proteases and HER ligands through a feedback loop mediates acquired resistance to trastuzumab in HER2-amplified breast cancer
M Gijsen, P King, T Perera, P Parker, B Larijani, A Harris, A Kong
Breast Cancer Research , 2010, DOI: 10.1186/bcr2493
Abstract: We used a multidisciplinary approach including fluorescence resonance energy transfer and biochemical methods to assess the effects of Herceptin on various signalling pathways and to determine the acquired resistance mechanisms of Herceptin in various HER2-positive breast cell lines and a BT474 xenograft model.We have shown that Herceptin does not decrease HER2 phosphorylation despite the effect on HER2 receptor downregulation. HER2 phosphorylation is maintained by the activation of EGFR, HER3 and HER4 via their dimerisation with HER2 in breast cancer cells. The activation of EGFR, HER3 and HER4 is induced by HER ligand release, including heregulin and betacellulin. The release of HER ligands is mediated by ADAM proteases including ADAM17/TACE. Furthermore, we demonstrated that the feedback loop involving HER ligands and ADAM proteases is activated due to a decrease in PKB phosphorylation induced by Herceptin treatment. The feedback loop is also switched on when PKB phosphorylation is decreased by a PKB inhibitor. We have shown that the feedback loop activates the HER receptors and maintains HER2 phosphorylation in response to Herceptin. Herceptin in combination with a panHER inhibitor also caused a much greater tumour inhibition compared with Herceptin or panHER inhibitor alone in the xenograft model.Our data provide evidence that Herceptin as monotherapy may result in poor outcome for patients due to the escape mechanisms through a feedback loop involving the upregulation of ADAM proteases and HER ligands. We have provided a novel mechanism of acquired resistance to Herceptin in HER2-positive breast cancer and have resolved the inconsistencies in the literature regarding the effect of Herceptin on HER2 phosphorylation.
Fluctuations and correlations in a frustrated S=1/2 square lattice with competing ferromagnetic and antiferromagnetic interactions: a muSR study
P. Carretta,M. Filibian,R. Nath,C. Geibel,P. J. C. King
Physics , 2009, DOI: 10.1103/PhysRevB.79.224432
Abstract: Zero and longitudinal field $\mu$SR measurements in Pb$_2$VO(PO$_4$)$_2$ and BaCdVO(PO$_4$)$_2$, two prototypes of the frustrated $S=1/2$ square lattice model with competing ferromagnetic and antiferromagnetic interactions, are presented. Both systems are observed to undergo a phase transition to a long-range magnetic order at $T_N\simeq 3.46$ K, for Pb$_2$VO(PO$_4$)$_2$, and at $T_N\simeq 0.99$ K, for BaCdVO(PO$_4$)$_2$. In Pb$_2$VO(PO$_4$)$_2$ both the temperature dependence of the order parameter and the longitudinal relaxation rate above $T_N$ are consistent with a two-dimensional XY model. On the other hand, for BaCdVO(PO$_4$)$_2$, which lies very close to the magnetically disordered region of the phase diagram where a bond-nematic order was predicted, a peculiar logarithmic increase of the relaxation is observed above $T_N$. In both systems a rather broad distribution of internal fields at the muon sites is noticed below $T_N$. The origin of this distribution is discussed in the light of the $\mu$SR experiments already performed on $S=1/2$ frustrated antiferromagnets on a square lattice.
The Effects of Substituting Glassware for Plasticware and the Use of an Ethanol Vector on Oocyte Maturation In Vitro
A. D. Macaulay,C. K. Hamilton,P. M. Bartlewski,W. A. King
Veterinary Medicine International , 2012, DOI: 10.1155/2012/914715
Abstract: The intent of this study was to evaluate specific technical aspects of in vitro oocyte maturation (IVM), which included container material and solvent delivery vector. Oocytes were matured in oil-free, open-well systems contained in either plastic or glass dishes and compared to control oocytes matured in media droplets on plastic dishes overlaid with mineral oil. Open-well experiments were repeated with ethanol in a quantity sufficient for delivery of nonmiscible compounds. Cleavage rates were significantly decreased in the glassware system when compared to controls. The plasticware open-well system did not differ from either the controls or the glassware groups. Cleavage in glassware with ethanol was significantly lower than controls or plasticware with ethanol. Blastocyst rates were only decreased in the glassware-ethanol treatment when compared to plasticware-ethanol treatment. Cell counts and percentage of TUNEL-positive cells did not differ significantly. Unexpectedly, sex ratio was significantly decreased (34% male) from the expected value of 50% male in the glassware group with added ethanol. The current study demonstrates the sensitivity of IVM to subtle technical changes, resulting in significant developmental consequences. 1. Introduction Appropriate nuclear and cytoplasmic maturation is essential for an oocyte to prepare for fertilization and to develop into an embryo [1]. Embryo production in vitro utilizes complex media that coincides to each step in oocyte development: maturation, fertilization, and culture. Common in vitro practice exposes cumulus oocyte complexes to a number of substrates including hormones during maturation. Often luteinizing hormone (LH), follicle-stimulating hormone, (FSH), and estradiol are added to IVM media; however, other steroid hormones like androgens [2, 3] or thyroid hormones [4] have been explored because of their classic role in physiology, inducing growth. The contribution of other factors has been explored in vitro including biologically derived additives [5, 6], energy sources like pyruvate or glucose [7, 8], and also fully defined media devoid of any unknown biological extracts like serum [6, 9, 10]. Furthermore, the effects of vectors like ethanol (EtOH) [2] and dimethyl sulfoxide (DMSO) [11] which can be used for delivery of poorly water-soluble steroids have been explored. It has been shown that small volumes of EtOH and DMSO (≤1%) do not influence oocyte maturation, but levels of 0.3% or higher can negatively impact blastocyst production [11]. Culture media and the components that comprise it play
Variation at Innate Immunity Toll-Like Receptor Genes in a Bottlenecked Population of a New Zealand Robin
Catherine E. Grueber, Graham P. Wallis, Tania M. King, Ian G. Jamieson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045011
Abstract: Toll-like receptors (TLRs) are an ancient family of genes encoding transmembrane proteins that bind pathogen-specific molecules and initiate both innate and adaptive aspects of the immune response. Our goal was to determine whether these genes show sufficient genetic diversity in a bottlenecked population to be a useful addition or alternative to the more commonly employed major histocompatibility complex (MHC) genotyping in a conservation genetics context. We amplified all known avian TLR genes in a severely bottlenecked population of New Zealand's Stewart Island robin (Petroica australis rakiura), for which reduced microsatellite diversity was previously observed. We genotyped 17–24 birds from a reintroduced island population (including the 12 founders) for nine genes, seven of which were polymorphic. We observed a total of 24 single-nucleotide polymorphisms overall, 15 of which were non-synonymous, representing up to five amino-acid variants at a locus. One locus (TLR1LB) showed evidence of past directional selection. Results also confirmed a passerine duplication of TLR7. The levels of TLR diversity that we observe are sufficient to justify their further use in addressing conservation genetic questions, even in bottlenecked populations.
Policy Adjustment in a Dynamic Economic Game
Jian Li, Samuel M. McClure, Brooks King-Casas, P. Read Montague
PLOS ONE , 2006, DOI: 10.1371/journal.pone.0000103
Abstract: Making sequential decisions to harvest rewards is a notoriously difficult problem. One difficulty is that the real world is not stationary and the reward expected from a contemplated action may depend in complex ways on the history of an animal's choices. Previous functional neuroimaging work combined with principled models has detected brain responses that correlate with computations thought to guide simple learning and action choice. Those works generally employed instrumental conditioning tasks with fixed action-reward contingencies. For real-world learning problems, the history of reward-harvesting choices can change the likelihood of rewards collected by the same choices in the near-term future. We used functional MRI to probe brain and behavioral responses in a continuous decision-making task where reward contingency is a function of both a subject's immediate choice and his choice history. In these more complex tasks, we demonstrated that a simple actor-critic model can account for both the subjects' behavioral and brain responses, and identified a reward prediction error signal in ventral striatal structures active during these non-stationary decision tasks. However, a sudden introduction of new reward structures engages more complex control circuitry in the prefrontal cortex (inferior frontal gyrus and anterior insula) and is not captured by a simple actor-critic model. Taken together, these results extend our knowledge of reward-learning signals into more complex, history-dependent choice tasks. They also highlight the important interplay between striatum and prefrontal cortex as decision-makers respond to the strategic demands imposed by non-stationary reward environments more reminiscent of real-world tasks.
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