758 research outputs found

    New Orleans, Nodal Point of the French Atlantic

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    This article argues for the importance of New Orleans within French and Francophone Studies, with a particular emphasis on a French Atlantic perspective. A historical overview discusses the role of New France, slavery, native Americans, Spain, immigration from Saint-Domingue, the Louisiana Purchase and the American Civil War in the formation of the city, and the rich and under-researched field of the city’s nineteenth-century literary output in French is surveyed. Among the unique aspects of this history are the coherent African cultures exported to Louisiana due to the trafficking of slaves of mostly Bambara ethnicity, their crucial role in the material survival of the colony, and the large presence – from intermarriage, manumission under Spanish rule, and an influx following the Haitian revolution - of free people of colour who contributed to the formation of a Caribbean-type racial hierarchy that did not exist elsewhere in the United States. The article ends with an overview of French representations of the city, in particular A Cotton Office in New Orleans by Edgar Degas, and the city’s place in world tourism, generating questions about the mobile and hybrid meanings attaching to ‘Frenchness’ in this context

    Iodine binding to humic acid

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    The rate of reactions between humic acid (HA) and iodide (I-) and iodate (IO3-) have been investigated in suspensions spiked with 129I at concentrations of 22, 44 and 88 µg L-1 and stored at 10oC. Changes in the speciation of 129I-, 129IO3- and mixed (129I-+129IO3-) spikes were monitored over 77 days using liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS). In suspensions spiked with 129I- 25% of the added I- was transformed into organic iodine (Org-129I) within 77 days and there was no evidence of 129IO3- formation. By contrast, rapid loss of 129IO3- and increase in both 129I- and Org-129I was observed in 129IO3--spiked suspensions. However, the rate of Org-129I production was greater in mixed systems compared to 129IO3--spiked suspensions with the same total 129I concentration, possibly indicating IO3-—I- redox coupling. Size exclusion chromatography (SEC) demonstrated that Org-129I was present in both high and low molecular weight fractions of the HA although a slight preference to bond with the lower molecular weight fractions was observed indicating that, after 77 days, the spiked isotope had not fully mixed with the native 127I pool. Iodine transformations were modelled using first order rate equations and fitted rate coefficients determined. However, extrapolation of the model to 250 days indicated that a pseudo-steady state would be attained after ~ 200 days but that the proportion of 129I incorporated into HA was less than that of 127I indicating the presence of a recalcitrant pool of 127I that was unavailable for isotopic mixing

    Emergent eddy saturation from an energy constrained eddy parameterisation

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    The large-scale features of the global ocean circulation and the sensitivity of these features with respect to forcing changes are critically dependent upon the influence of the mesoscale eddy field. One such feature, observed in numerical simulations whereby the mesoscale eddy field is at least partially resolved, is the phenomenon of eddy saturation, where the time-mean circumpolar transport of the Antarctic Circumpolar Current displays relative insensitivity to wind forcing changes. Coarse-resolution models employing the Gent--McWilliams parameterisation with a constant Gent--McWilliams coefficient seem unable to reproduce this phenomenon. In this article, an idealised model for a wind-forced, zonally symmetric flow in a channel is used to investigate the sensitivity of the circumpolar transport to changes in wind forcing under different eddy closures. It is shown that, when coupled to a simple parameterised eddy energy budget, the Gent--McWilliams coefficient of the form described in Marshall et al. (2012) [A framework for parameterizing eddy potential vorticity fluxes, J. Phys. Oceanogr., vol. 42, 539--557], which includes a linear eddy energy dependence, produces eddy saturation as an emergent property.Comment: 22 pages, 10 figures, Elsevier template, submitted to Ocean Modelling; comments welcom

    Magnetic Properties of YBa_2Cu_3O_{7-\delta} in a self-consistent approach: Comparison with Quantum-Monte-Carlo Simulations and Experiments

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    We analyze single-particle electronic and two-particle magnetic properties of the Hubbard model in the underdoped and optimally-doped regime of \YBCO by means of a modified version of the fluctuation-exchange approximation, which only includes particle-hole fluctuations. Comparison of our results with Quantum-Monte Carlo (QMC) calculations at relatively high temperatures (T∼1000KT\sim 1000 K) suggests to introduce a temperature renormalization in order to improve the agreement between the two methods at intermediate and large values of the interaction UU. We evaluate the temperature dependence of the spin-lattice relaxation time T1T_1 and of the spin-echo decay time T2GT_{2G} and compare it with the results of NMR measurements on an underdoped and an optimally doped \YBCO sample. For U/t=4.5U/t=4.5 it is possible to consistently adjust the parameters of the Hubbard model in order to have a good {\it semi-quantitative} description of this temperature dependence for temperatures larger than the spin gap as obtained from NMR measurements. We also discuss the case U/t∼8U/t\sim 8, which is more appropriate to describe magnetic and single-particle properties close to half-filling. However, for this larger value of U/tU/t the agreement with QMC as well as with experiments at finite doping is less satisfactory.Comment: Final version, to appear in Phys. Rev. B (sched. Feb. 99

    Swift follow-up of the Gravitational Wave source GW150914

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    The Advanced Laser Interferometer Gravitational-Wave Observatory (ALIGO) observatory recently reported the first direct detection of gravitational waves (GW) which triggered ALIGO on 2015 September 14. We report on observations taken with the Swift satellite two days after the trigger. No new X-ray, optical, UV or hard X-ray sources were detected in our observations, which were focused on nearby galaxies in the GW error region and covered 4.7 deg2 (~2 per cent of the probability in the rapidly available GW error region; 0.3 per cent of the probability from the final GW error region, which was produced several months after the trigger). We describe the rapid Swift response and automated analysis of the X-ray telescope and UV/Optical telescope data, and note the importance to electromagnetic follow-up of early notification of the progenitor details inferred from GW analysis

    Whole-exome sequencing and targeted copy number analysis in primary ciliary dyskinesia

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    Primary ciliary dyskinesia (PCD) is an autosomal-recessive disorder resulting from loss of normal ciliary function. Symptoms include neonatal respiratory distress, chronic sinusitis, bronchiectasis, situs inversus, and infertility. Clinical features may be subtle and highly variable, making the diagnosis of PCD challenging. The diagnosis can be confirmed with ciliary ultrastructure analysis and/or molecular genetic testing of 32 PCD-associated genes. However, because of this genetic heterogeneity, comprehensive molecular genetic testing is not considered the standard of care, and the most efficient molecular approach has yet to be elucidated. Here, we propose a cost-effective and time-efficient molecular genetic algorithm to solve cases of PCD. We conducted targeted copy number variation (CNV) analysis and/or whole-exome sequencing on 20 families (22 patients) from a subset of 45 families (52 patients) with a clinical diagnosis of PCD who did not have a molecular genetic diagnosis after Sanger sequencing of 12 PCD-associated genes. This combined molecular genetic approach led to the identification of 4 of 20 (20%) families with clinically significant CNVs and 7 of 20 (35%) families with biallelic pathogenic mutations in recently identified PCD genes, resulting in an increased molecular genetic diagnostic rate of 55% (11/20). In patients with a clinical diagnosis of PCD, whole-exome sequencing followed by targeted CNV analysis results in an overall molecular genetic yield of 76% (34/45)

    Greater physical activity is associated with neuroretinal thinning in glaucomatous and normative cohorts

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    Ella Claire Berry, Henry Marshall, Sean Mullany, Santiago Diaz Torres, Joshua Schmidt, Daniel Thomson, Mark Hassall, Stewart R Lake, Richard A Mills, John Landers, Stuart MacGregor, Robert Casson, Owen Siggs, Jamie E Crai
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