520 research outputs found

    Modelling storm responses on a high-energy coastline with XBeach

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    The XBeach model has been used to simulate the morphological impacts of storms on sandy and gravel beaches. Taking as a case study Rossbeigh Spit located on the high-energy coast of western Ireland, the study reported here tests the capacity of XBeach to reproduce barrier breaching during a storm in December 2008. It demonstrates that predictions of the breaching event agree reasonably well with observations. However, the main focus of the paper is to establish using the model results, site-specific critical wave and water level conditions giving rise to dune erosion, overwashing and breaching. By deriving simple-to-use expressions to define hydrodynamic thresholds the study advances the ability to predict the impacts of infrequent and rarely observed storm events and is considered to provide useful coastal management tool for assessing the vulnerability of sandy barriers to breaching high-energy during storms

    Polarization mode dispersion compensator field trial and field fiber characterization

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    Two high-PMD long distance routes were characterized and used to test an optical polarization mode dispersion compensator (PMDC) under field conditions. For this trial, 110 km routes with mean PMD values of 25 and 26.5 ps were provisioned with commercial WDM transport equipment and tested for several weeks. The route was comprised of three spans of characterized fiber that followed railroad tracks. We show the temporal variation of the output polarization state and the evolution of first- and second-order PMD spectra over 7 days. The deployment of a variable-length PMDC on these links allowed error-free transmission of an OC-192 signal. Splitting the output to receivers with and without PMDC demonstrated specific PMD events that caused errors in the absence of a PMDC. (C) 2002 Optical Society of America

    Family environment is associated with endemic Burkitt lymphoma: a population-based case-control study

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    Endemic Burkitt\u27s lymphoma (eBL) has been linked to Epstein-Barr virus and holoendemic Plasmodium falciparum malaria. These co-infections, however, are insufficient to explain the non-random occurrence of Endemic Burkitt\u27s lymphoma within Equatorial Africa. To explore whether this distribution could be explained by household characteristics and family environment, we conducted a case-control study using 41 hospitalized incident endemic Burkitt\u27s lymphoma cases and 91 healthy controls identified through a population-based multistage cluster-sampling scheme in Nyanza Province, Kenya. In a multivariate analysis, odds ratios associated with having one, two, and three or more younger siblings compared with none were 0.28 (90% CI: 0.09, 0.83), 0.59 (90% CI: 0.16, 2.23) and 0.15 (90% CI: 0.03, 0.67) respectively, suggesting that children with endemic Burkitt\u27s lymphoma were more likely than controls to be last-born. Children with endemic Burkitt\u27s lymphoma were also more likely to live in non-monogamous families (OR=3.12, 90% CI:1.19, 8.17) and to have at least one deceased parent (OR=3.38, 90% CI: 1.18, 9.64). Household characteristics, especially sibship relationships, may contribute to endemic Burkitt\u27s lymphoma and therefore warrant further study

    The Human Lipodystrophy Gene BSCL2/Seipin May Be Essential for Normal Adipocyte Differentiation

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    OBJECTIVE—Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is a recessive disorder featuring near complete absence of adipose tissue. Remarkably, although the causative gene, BSCL2, has been known for several years, its molecular function and its role in adipose tissue development have not been elucidated. Therefore, we examined whether BSCL2 is involved in the regulation of adipocyte differentiation and the mechanism whereby pathogenic mutations in BSCL2 cause lipodystrophy
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