1,079 research outputs found

    Regional Pliocene exhumation of the Lesser Himalaya in the Indus drainage

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    New bulk sediment Sr and Nd isotope data, coupled with U–Pb dating of detrital zircon grains from sediment cored by the International Ocean Discovery Program in the Arabian Sea, allow the reconstruction of erosion in the Indus catchment since ∌17&thinsp;Ma. Increasing ΔNd values from 17 to 9.5&thinsp;Ma imply relatively more erosion from the Karakoram and Kohistan, likely linked to slip on the Karakoram Fault and compression in the southern and eastern Karakoram. After a period of relative stability from 9.5 to 5.7&thinsp;Ma, there is a long-term decrease in ΔNd values that corresponds with increasing relative abundance of &gt;300&thinsp;Ma zircon grains that are most common in Himalayan bedrocks. The continuous presence of abundant Himalayan zircons precludes large-scale drainage capture as the cause of decreasing ΔNd values in the submarine fan. Although the initial increase in Lesser Himalaya-derived 1500–2300&thinsp;Ma zircons after 8.3&thinsp;Ma is consistent with earlier records from the foreland basin, the much greater rise after 1.9&thinsp;Ma has not previously been recognized and suggests that widespread unroofing of the Crystalline Lesser Himalaya and to a lesser extent Nanga Parbat did not occur until after 1.9&thinsp;Ma. Because regional erosion increased in the Pleistocene compared to the Pliocene, the relative increase in erosion from the Lesser Himalaya does not reflect slowing erosion in the Karakoram and Greater Himalaya. No simple links can be made between erosion and the development of the South Asian Monsoon, implying a largely tectonic control on Lesser Himalayan unroofing.</p

    Slip-velocity of large neutrally-buoyant particles in turbulent flows

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    We discuss possible definitions for a stochastic slip velocity that describes the relative motion between large particles and a turbulent flow. This definition is necessary because the slip velocity used in the standard drag model fails when particle size falls within the inertial subrange of ambient turbulence. We propose two definitions, selected in part due to their simplicity: they do not require filtration of the fluid phase velocity field, nor do they require the construction of conditional averages on particle locations. A key benefit of this simplicity is that the stochastic slip velocity proposed here can be calculated equally well for laboratory, field, and numerical experiments. The stochastic slip velocity allows the definition of a Reynolds number that should indicate whether large particles in turbulent flow behave (a) as passive tracers; (b) as a linear filter of the velocity field; or (c) as a nonlinear filter to the velocity field. We calculate the value of stochastic slip for ellipsoidal and spherical particles (the size of the Taylor microscale) measured in laboratory homogeneous isotropic turbulence. The resulting Reynolds number is significantly higher than 1 for both particle shapes, and velocity statistics show that particle motion is a complex non-linear function of the fluid velocity. We further investigate the nonlinear relationship by comparing the probability distribution of fluctuating velocities for particle and fluid phases

    Anomalous origin of the left coronary artery from the pulmonary artery: case report and review

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    Anomalous origin of the left coronary artery from the pulmonary artery is a rare congenital condition that proves to be fatal in most individuals during childhood due to significant left ventricular ischaemia. However, there are case reports of individuals surviving into adulthood that have varying presenting symptoms. We report a case of a young male, who presented to our cardiology clinic with typical ischaemic cardiac pain, with no established risk factors, and was found to have anomalous origin of the left coronary artery from the pulmonary artery that was subsequently surgically corrected

    Carbon nanotubes: an insight into the mechanisms of their potential genotoxicity

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    After the health catastrophe resulting from the widespread use of asbestos which was once hailed as a new miracle material, the increasing use of carbon nanotubes (CNTs) has spawned major concern due to their similarities in terms of size, shape and poor solubility. Assessment of genotoxicity has shown that CNTs can damage DNA in vitro and in vivo. The genotoxic potential of different CNT samples varies considerably, however, with negative findings reported in a number of studies, probably due to the enormous heterogeneity of CNTs. The observed spectrum of genotoxic effects shows similarities with those reported for asbestos fibres. Mutagenicity has been found in vivo but in bacterial assays both asbestos and CNTs have mostly tested negative. An overview of key experimental observations on CNT-induced genotoxicity is presented in the first half of this review.In the second part, the potential mechanisms of CNT-elicited genotoxicity are discussed. Whereas CNTs possess intrinsic ROS-scavenging properties they are capable of generating intracellular ROS upon interaction with cellular components, and can cause antioxidant depletion. These effects have been attributed to their Fenton-reactive metals content. In addition, CNTs can impair the functionality of the mitotic apparatus. A noteworthy feature is that frustrated phagocytosis, which is involved in asbestos-induced pathology, has been observed for specific CNTs as well. The involvement of other mechanisms generally implicated in particle toxicity, such as phagocyte activation and impairment of DNA repair, is largely unknown at present and needs further investigation

    Tawney and the third way

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    From the 1920s to the 1950s R. H. Tawney was the most influential socialist thinker in Britain. He articulated an ethical socialism at odds with powerful statist and mechanistic traditions in British socialist thinking. Tawney's work is thus an important antecedent to third way thinking. Tawney's religiously-based critique of the morality of capitalism was combined with a concern for detailed institutional reform, challenging simple dichotomies between public and private ownership. He began a debate about democratizing the enterprise and corporate governance though his efforts fell on stony ground. Conversely, Tawney's moralism informed a whole-hearted condemnation of market forces in tension with both his concern with institutional reform and modern third way thought. Unfortunately, he refused to engage seriously with emergent welfare economics which for many social democrats promised a more nuanced understanding of the limits of market forces. Tawney's legacy is a complex one, whose various elements form a vital part of the intellectual background to current third way thinking

    The political economy of the Jospin government

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    This article explores the political economy of the French Socialist Party (PS), beginning with the neo-liberal U-turn of 1983. It then charts the re-evaluation of the PS's political economic foundations after the 1993 defeat, the rejection of the neo-liberal 'pensée unique', and the rehabilitation of a broadly Keynesian frame of reference. The article goes on to explore how this shift has fed through into the Jospin government's policy and positions at both the national and international level. It explores aspirations to reinvent the EU as a Keynesian social democratic 'policy space', and at the national level, employment, macroeconomic, and structural policies

    Neoglacial climate anomalies and the Harappan metamorphosis

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    Climate exerted constraints on the growth and decline of past human societies but our knowledge of temporal and spatial climatic patterns is often too restricted to address causal connections. At a global scale, the inter-hemispheric thermal balance provides an emergent framework for understanding regional Holocene climate variability. As the thermal balance adjusted to gradual changes in the seasonality of insolation, the Intertropical Convergence Zone migrated southward accompanied by a weakening of the Indian summer monsoon. Superimposed on this trend, anomalies such as the Little Ice Age point to asymmetric changes in the extratropics of either hemisphere. Here we present a reconstruction of the Indian winter monsoon in the Arabian Sea for the last 6000 years based on paleobiological records in sediments from the continental margin of Pakistan at two levels of ecological complexity: Sedimentary ancient DNA reflecting water column environmental states and planktonic foraminifers sensitive to winter conditions. We show that strong winter monsoons between ca. 4500 and 3000 years ago occurred during a period characterized by a series of weak interhemispheric temperature contrast intervals, which we identify as the early neoglacial anomalies (ENA). The strong winter monsoons during ENA were accompanied by changes in wind and precipitation patterns that are particularly evident across the eastern Northern Hemisphere and tropics. This coordinated climate reorganization may have helped trigger the metamorphosis of the urban Harappan civilization into a rural society through a push-pull migration from summer flood-deficient river valleys to the Himalayan piedmont plains with augmented winter rains. The decline in the winter monsoon between 3300 and 3000 years ago at the end of ENA could have played a role in the demise of the rural late Harappans during that time as the first Iron Age culture established itself on the Ghaggar-Hakra interfluve. Finally, we speculate that time-transgressive land cover changes due to aridification of the tropics may have led to a generalized instability of the global climate during ENA at the transition from the warmer Holocene thermal maximum to the cooler Neoglacial

    Integrating silver compounds and nanoparticles into ceria nanocontainers for antimicrobial applications

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    Silver compounds and nanoparticles (NPs) are gaining increasing interest in medical applications, specifically in the treatment and prevention of biomaterial-related infections. However, the silver release from these materials, resulting in a limited antimicrobial activity, is often difficult to control. In this paper, ceria nanocontainers were synthesized by a template-assisted method and were then used to encapsulate silver nitrate (AgNO₃/CeO₂ nanocontainers). Over the first 30 days, a significant level of silver was released, as determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). A novel type of ceria container containing silver NPs (AgNP/CeO₂ containers) was also developed using two different template removal methods. The presence of AgNPs was confirmed both on the surface and in the interior of the ceria containers by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Upon removal of the template by calcination, the silver was released over a period exceeding three months (>90 days). However, when the template was removed by dissolution, the silver release was shortened to ≀14 days. The antimicrobial activity of the silver-containing CeO₂ containers was observed and the minimum bactericidal concentration (MBC) was determined using the broth dilution method. Investigation on human cells, using a model epithelial barrier cell type (A549 cells), highlighted that all three samples induced a heightened cytotoxicity leading to cell death when exposed to all containers in their raw form. This was attributed to the surface roughness of the CeO₂ nanocontainers and the kinetics of the silver release from the AgNO₃/CeO₂ and AgNP/CeO₂ nanocontainers. In conclusion, despite the need for further emphasis on their biocompatibility, the concept of the AgNP/CeO₂ nanocontainers offers a potentially alternative long-term antibactericidal strategy for implant materials

    A Comparative Study of Different In Vitro Lung Cell Culture Systems to Assess the Most Beneficial Tool for Screening the Potential Adverse Effects of Carbon Nanotubes

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    To determine the potential inhalatory risk posed by carbon nanotubes (CNTs), a tier-based approach beginning with an in vitro assessment must be adopted. The purpose of this study therefore was to compare 4 commonly used in vitro systems of the human lung (human blood monocyte-derived macrophages [MDM] and monocyte-derived dendritic cells [MDDC], 16HBE14o- epithelial cells, and a sophisticated triple cell co-culture model [TCC-C]) via assessment of the biological impact of different CNTs (single-walled CNTs [SWCNTs] and multiwalled CNTs [MWCNTs]) over 24h. No significant cytotoxicity was observed with any of the cell types tested, although a significant (p < .05), dose-dependent increase in tumor necrosis factor (TNF)-α following SWCNT and MWCNT exposure at concentrations up to 0.02mg/ml to MDM, MDDC, and the TCC-C was found. The concentration of TNF-α released by the MDM and MDDC was significantly higher (p < .05) than the TCC-C. Significant increases (p < .05) in interleukin (IL)-8 were also found for both 16HBE14o- epithelial cells and the TCC-C after SWCNTs and MWCNTs exposure up to 0.02mg/ml. The TCC-C, however, elicited a significantly (p < .05) higher IL-8 release than the epithelial cells. The oxidative potential of both SWCNTs and MWCNTs (0.005-0.02mg/ml) measured by reduced glutathione (GSH) content showed a significant difference (p < .05) between each monoculture and the TCC-C. It was concluded that because only the co-culture system could assess each endpoint adequately, that, in comparison with monoculture systems, multicellular systems that take into consideration important cell type-to-cell type interactions could be used as predictive in vitro screening tools for determining the potential deleterious effects associated with CNT

    Post-democracy and institutionalized austerity in France:budgetary politics during François Hollande’s presidency

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    This paper applies the concept of post-democracy coined by Crouch to shed light on the emerging political dynamics of macro-economic policy coordination in the Eurozone as they applied to France during Hollande’s presidency. Firstly, the paper explains the nature of EMU reform, characterized here as post-democratic by institutional design, before analysing its impact on France’s budgetary politics. Finally, the French case involving Hollande’s balancing act between supranational rules and domestic spending preferences is used as a way to reflect on the stability of this post-democratic arrangement for rescuing the Euro. The 2017 presidential election pitting Macron against Le Pen showed that post-democracy by design is sustainable only if the supply side of politics remains supportive of EMU – a condition undermined by the institutionalization of austerity, at least in France
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