1,125 research outputs found
An evaluation of Paralytic Shellfish Toxin occurrence and magnitude around the UK coast since 2008; using chemotaxonomy to maximise routine monitoring data
A dedicated monitoring programme exists within the UK for the analysis of marine biotoxins of microalgal origin, in shellfish from classified production areas. For England, Wales and Scotland this is currently delivered by Cefas on behalf of the Food Standards Agency (FSA) and Food Standards Scotland (FSS). This monitoring programme tests for three groups of toxins, including the paralytic shellfish toxins (PSTs), using chemical analytical techniques, as well as identifying their causative organisms, using light microscopy. Although toxicity and toxin profile within shellfish from around the UK is well documented, since the implementation of chemical analytical testing, the underlying causative microalgal species remain undetermined in most areas. This is due to a lack of resource within the monitoring programme to perform definitive identification following light microscopy and a lack of specific research work confirming the toxin producers in all areas. Presented here is an analysis of PST shellfish toxicity data from the UK monitoring programme displaying trends in distribution and magnitude of PSTs in shellfish over the last 15 years of monitoring. Further to this, toxin profile data generated following the implementation of HPLC-FLD for monitoring PSTs is analysed. This PST toxin profile analysis is used to offer a possible proxy method for the identification of microalgal species by their differing PST toxin profile as presented in the literature. The possible distribution of causative organisms is evaluated using this chemotaxonomic technique to allow for targeted future work
A review of the global distribution of Alexandrium minutum (Dinophyceae) and comments on ecology and associated paralytic shellfish toxin profiles, with a focus on Northern Europe
Alexandrium minutum is a globally distributed harmful algal bloom species with many strains that are known to produce paralytic shellfish toxins (PSTs) and consequently represent a concern to human and ecosystem health. This review highlights that A. minutum typically occurs in sheltered locations, with cell growth occurring during periods of stable water conditions. Sediment characteristics are important in the persistence of this species within a location, with fine sediments providing cyst deposits for ongoing inoculation to the water column. Toxic strains of A. minutum do not produce a consistent toxin profile, different populations produce a range of PSTs in differing quantities. Novel cluster analysis of published A. minutum toxin profiles indicates five PST profile clusters globally. Some clusters are grouped geographically (Northern Europe) whilst others are widely spread. Isolates from Taiwan have a range of toxin profile clusters and this area appears to have the most diverse set of PST producing A. minutum populations. These toxin profiles indicate that within the UK there are two populations of A. minutum grouping with strains from Northern France and Southern Ireland. There is a degree of interconnectivity in this region due to oceanic circulation and a high level of shipping and recreational boating. Further research into the interrelationships between the A. minutum populations in this global region would be of value
Tuna research and monitoring in the South Pacific
The island countries of the South Pacific have adopted a regional approach to the development and management of tuna resources, through 2 organizations based in the region - the Forum Fisheries Agency and the South Pacific Commission. Details are given of the Tuna and Billfish Assessment Programme, which involves tropical tunas and albacore
Tuna research and monitoring in the South Pacific
Tuna fisheries, Research programmes, Monitoring, Stock assessment, Tagging, South Pacific,
Asymmetry sum rule for molecular predissociation
© 2000 American Physical SocietyIn the case of weak diatomic molecular predissociation by noninteracting, optically inactive continuum states, it is demonstrated that the predissociation line shape is more accurately represented by a Beutler-Fano profile than by a Lorentzian. The weak asymmetry that is found to occur is due principally to interactions with neighboring vibrational resonances. For this type of predissociation in the case of multiple continua, a sum rule for the corresponding line-shape asymmetry is derived. This sum rule is verified numerically using single-channel and multichannel coupled Schrödinger-equation calculations for the Schumann-Runge band system of O2. Similar results are presented for the case of optically active continua.F. T. Hawes, L. W. Torop, B. R. Lewis and S. T. Gibso
A model structure for coloured operads in symmetric spectra
We describe a model structure for coloured operads with values in the
category of symmetric spectra (with the positive model structure), in which
fibrations and weak equivalences are defined at the level of the underlying
collections. This allows us to treat R-module spectra (where R is a cofibrant
ring spectrum) as algebras over a cofibrant spectrum-valued operad with R as
its first term. Using this model structure, we give suficient conditions for
homotopical localizations in the category of symmetric spectra to preserve
module structures.Comment: 16 page
Probing neutrino masses with future galaxy redshift surveys
We perform a new study of future sensitivities of galaxy redshift surveys to
the free-streaming effect caused by neutrino masses, adding the information on
cosmological parameters from measurements of primary anisotropies of the cosmic
microwave background (CMB). Our reference cosmological scenario has nine
parameters and three different neutrino masses, with a hierarchy imposed by
oscillation experiments. Within the present decade, the combination of the
Sloan Digital Sky Survey (SDSS) and CMB data from the PLANCK experiment will
have a 2-sigma detection threshold on the total neutrino mass close to 0.2 eV.
This estimate is robust against the inclusion of extra free parameters in the
reference cosmological model. On a longer term, the next generation of
experiments may reach values of order sum m_nu = 0.1 eV at 2-sigma, or better
if a galaxy redshift survey significantly larger than SDSS is completed. We
also discuss how the small changes on the free-streaming scales in the normal
and inverted hierarchy schemes are translated into the expected errors from
future cosmological data.Comment: 14 pages, 7 figures. Added results with the KAOS proposal and 1
referenc
The Topology and Size of the Universe from the Cosmic Microwave Background
We study the possibility that the universe has compact topologies T^3, T^2 x
R^1, or S^1 x R^2 using the seven-year WMAP data. The maximum likelihood 95%
confidence intervals for the size L of the compact direction are 1.7 < L/L_0 <
2.1, 1.8 < L/L_0 < 2.0, 1.2 < L/L_0 < 2.1 for the three cases, respectively,
where L_0=14.4 Gpc is the distance to the last scattering surface. An infinite
universe is compatible with the data at 4.3 sigma. We find using a Bayesian
analysis that the most probable universe has topology T^2 x R^1, with
L/L_0=1.9.Comment: Additional checks, Monte-Carlo skies, and study of dipole
contamination added. References added. 13 pages, 11 figure
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