Early-Middle Pleistocene Beheading of the River Thames

This paper marks the centenary of the first of three articles by W.M. Davis on the beheading of the Thames, beginning with a statement of his capture hypothesis in 1895 and concluding with attempts to explain anomalous misfit streams in 1899 and 1909. It discusses Davis's classic thesis of river capture by slow, long-term landscape evolution and his apparent reluctance to accept the fact of rapid Quaternary climate change. In contrast, recent work based on lithostratigraphy, biostratigraphy and morphostratigraphy emphasises the dynamism of the Quaternary Period and its influence on river capture. Possible mechanisms for the beheading of the Thames, tectonism, glacial erosion and conventional Davisian river capture, and the timing of the event, are discussed. In conclusion, the paper summarises known and unknown components of the problem of the beheading of the Thames, and discusses the extent of Davis's influence on later Thames studies.Cet article marque le centenaire du premier de trois articles consacrés par W.M. Davis à la capture de la Tamise qui commençait par une déclaration de son hypothèse de capture en 1895 et concluait par des tentatives d'explication du réseau inadapté, en 1899 et 1909. L'article discute de la thèse classique de Davis de capture suivant une évolution lente, à long terme, du paysage, et son apparente réticence à accepter le fait des changements climatiques rapides survenus au Quaternaire. Par opposition, les travaux récents, fondés sur la lithostratigraphie, la biostratigraphie et la morphostratigraphie, soulignent l'importance de la période quaternaire et son influence sur les captures. Les mécanismes pouvant être responsables de la capture de la Tamise, notamment la tectonique, l'érosion glaciaire, la capture fluviale classique selon Davis, ainsi que la chronologie des événements, sont discutés. En conclusion, cet article résume les faits connus et les éléments méconnus du problème de la capture de la Tamise et discute des limites de l'influence de Davis sur les études postérieures sur la Tamise.Dieser Artikel hebt den hundertsten Jahrestag des Erscheinens des ersten von drei Artikeln von W.M. Davis ïiber die Ablenkung der Themse hervor. Dieser begann 1895 mit der Darlegung seiner Ablenkungs-Hypothese und schloss 1899 und 1909 mit Erklàrungsversuchen anomaler unteroder uberfâhiger Strômungen. Der Artikel setzt sich mit Davis' klassischer These der Flussablenkung durch langsame langzeitige Landschaftsentwicklung auseinander sowei seinem Widerstreben, die Tatsache einer schnellen Klimaverànderung im Quartâr zu akzeptieren. Im Gegensatz dazu betonen neuere Arbeiten ausgehend von Lithostratigraphie, Biostratigraphie und Morphostratigraphie die Dynamik der Quartâr-Zeit und ihren Einfluss auf die Flussablenkung. Môgliche Mechanismen bei der Ablenkung der Themse wie Tektonik, glaziale Erosion und die konventionelle Flussablenkung nach Davis, sowie der zeitliche Ablauf dieses Geschehens werden diskutiert. Abschliessend fasst der Artikel bekannte und unbekannte Elemente des Problems der Ablenkung der Themse zusammen und erôrtert, inwieweit Davis spâtere Themse-Studien beeinflusst hat

Social Capital in Coordination Experiments: Risk, Trust and Position

Social capital theory is exemplary in attempting to integrate both individual and institutional perspectives in the study of governance, but interactions between the individual and institutional components remain underexplored and unspecified in many situations. We extend the theory from its focal attention on prisoners dilemma games to an important and understudied class of collective action problems of critical concern for governance— coordination tasks ranging from simple matching games to more complex tasks involving conflict (battle of the sexes) and assurance problems (stag hunt). Laboratory experiments provide a means of observing the impact of institutional influences (bridging and bonding network capital), individual predispositions (trust and risk aversion), and their interaction on the ability to coordinate in these settings. The results confirm that neither individual nor institutional components alone can explain coordination, and that interactions between these components must be understood in terms of the specific task context being studied

IFN-gamma regulation of ICAM-1 receptors in bronchial epithelial cells: soluble ICAM–1 release inhibits human rhinovirus infection

<p>Abstract</p> <p>Background</p> <p>Intercellular adhesion molecule-1 (ICAM-1) is a critical target-docking molecule on epithelial cells for 90% of human rhinovirus (HRV) serotypes. Two forms of ICAM-1 exist, membranous (mICAM-1) and soluble (sICAM-1), both expressed by bronchial epithelial cells. Interferon-gamma (IFN-γ), a crucial Th-1 immuno-regulatory mediator, can modulate mICAM-1 expression; however its simultaneous effects on mICAM-1: sICAM-1 levels and their consequent outcome on cell infectivity have not been previously explored.</p> <p>Methods</p> <p>Primary normal human bronchial epithelial cells were pre-stimulated with IFN-γ (1 ng/ml for 24 h) and subsequently inoculated with HRV-14 or HRV-1b (TCID₅₀10 ^2.5). Epithelial surface ICAM-1 expression and soluble ICAM-1 release were measured at the protein and gene level by immunofluorescence and ELISA respectively; mRNA levels were semi-quantified using RT-PCR. Molecular mechanisms regulating ICAM-1 isoform expression and effects on epithelial cell infectivity were explored.</p> <p>Results</p> <p>In IFN-γ-biased cells infected with HRV-14, but not HRV-1b, mICAM-1 expression is down-regulated, with simultaneous induction of sICAM-1 release. This differential effect on HRV-14 receptor isoforms appears to be related to a combination of decreased IFN-γ-induced JAK-STAT signalling and proteolytic receptor cleavage of the membranous form in IFN-γ-biased HRV-14 infected cells. The observed changes in relative mICAM-1: sICAM-1 expression levels are associated with reduced HRV-14 viral titres.</p> <p>Conclusion</p> <p>These findings support the hypothesis that in epithelial cells conditioned to IFN-γ and subsequently exposed to HRV-14 infection, differential modulation in the ratio of ICAM-1 receptors prevails in favour of an anti-viral milieu, appearing to limit further target cell viral attachment and propagation.</p

Giant Relaxation Oscillations in a Very Strongly Hysteretic SQUID ring-Tank Circuit System

In this paper we show that the radio frequency (rf) dynamical characteristics of a very strongly hysteretic SQUID ring, coupled to an rf tank circuit resonator, display relaxation oscillations. We demonstrate that the the overall form of these characteristics, together with the relaxation oscillations, can be modelled accurately by solving the quasi-classical non-linear equations of motion for the system. We suggest that in these very strongly hysteretic regimes SQUID ring-resonator systems may find application in novel logic and memory devices.Comment: 7 pages, 5 figures. Uploaded as implementing a policy of arXiving old paper

Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor

We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach

Pinch Resonances in a Radio Frequency Driven SQUID Ring-Resonator System

In this paper we present experimental data on the frequency domain response of a SQUID ring (a Josephson weak link enclosed by a thick superconducting ring) coupled to a radio frequency (rf) tank circuit resonator. We show that with the ring weakly hysteretic the resonance lineshape of this coupled system can display opposed fold bifurcations that appear to touch (pinch off). We demonstrate that for appropriate circuit parameters these pinch off lineshapes exist as solutions of the non-linear equations of motion for the system.Comment: 9 pages, 8 figures, Uploaded as implementing a policy of arXiving old paper

Pollutant dispersion in a developing valley cold-air pool

Pollutants are trapped and accumulate within cold-air pools, thereby affecting air quality. A numerical model is used to quantify the role of cold-air-pooling processes in the dispersion of air pollution in a developing cold-air pool within an alpine valley under decoupled stable conditions. Results indicate that the negatively buoyant downslope flows transport and mix pollutants into the valley to depths that depend on the temperature deficit of the flow and the ambient temperature structure inside the valley. Along the slopes, pollutants are generally entrained above the cold-air pool and detrained within the cold-air pool, largely above the ground-based inversion layer. The ability of the cold-air pool to dilute pollutants is quantified. The analysis shows that the downslope flows fill the valley with air from above, which is then largely trapped within the cold-air pool, and that dilution depends on where the pollutants are emitted with respect to the positions of the top of the ground-based inversion layer and cold-air pool, and on the slope wind speeds. Over the lower part of the slopes, the cold-air-pool-averaged concentrations are proportional to the slope wind speeds where the pollutants are emitted, and diminish as the cold-air pool deepens. Pollutants emitted within the ground-based inversion layer are largely trapped there. Pollutants emitted farther up the slopes detrain within the cold-air pool above the ground-based inversion layer, although some fraction, increasing with distance from the top of the slopes, penetrates into the ground-based inversion layer.Peer reviewe

The role of H2S bioavailability in endothelial dysfunction

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Endothelial dysfunction (EDF) reflects pathophysiological changes in the phenotype and functions of endothelial cells that result from and/or contribute to a plethora of cardiovascular diseases. We review the role of hydrogen sulfide (H2S) in the pathogenesis of EDF, one of the fastest advancing research topics. Conventionally treated as an environment pollutant, H2S is also produced in endothelial cells and participates in the fine regulation of endothelial integrity and functions. Disturbed H2S bioavailability has been suggested to be a novel indicator of EDF progress and prognosis. EDF manifests in different forms in multiple pathologies, but therapeutics aimed at remedying altered H2S bioavailability may benefit all.This work has been supported by a Discovery Grant from Natural Sciences and Engineering Research council of Canada to RW. CS has been supported by the American Diabetes Association, the National Institutes of Health of USA and the Shriners Hospitals for Children. FI has been supported by the National Institutes of Health of USA. MW has been supported by the Medical Research Council of UK. AA has been supported by programme grants from British Heart Foundation (RG/09/001/25940), Medical Research Council (G0700288), Royal Society and European Union. AP has been supported through an Aristeia grant (1436) that is co-financed by the European Union (ESF) and Greek national funds through the Operational Program “Education and Lifelong Learning”. MW and AP are supported by the COST Action BM1005 (ENOG: European network on gasotransmitters)