7,761 research outputs found
An Evaluation of the risks to food safety and shellfish farming in Great Britain,posed by marine biotoxins from, current and future emerging, marine microalgal species
Harmful marine microalgae are a global concern, impacting human and ecosystem health as well as having socioeconomic impacts for coastal communities. The changing world climate has an impact on marine organisms including the harmful algal species. These changes will have impacts on species already present in a nations waters whilst also influencing the emergence of novel species. This is assessed here, in part, with regards to Great Britain (GB).
This thesis explores the current extent of a harmful species, Alexandrium minutum, globally and in the South of GB. This shows that A. minutum occurs widely across the globe with different populations possessing varying toxin profiles. Populations from GB geographically neighbouring areas share similar toxin profiles. Within the South of GB, the current extent of A. minutum appears patchy, with evidence gathered by toxin profile analysis but successful germinations of vegetative cells from field samples proving unsuccessful. Experimental work determined a mechanism for the use of chemotaxonomy to differentiate the source of shellfish intoxications, allowing for separation of two key GB saxitoxin producers, A. minutum and Alexandrium catenella. This technique could enhance routine monitoring data with little additional cost.
Assessment of harmful microalgal taxa considered as non-native species (NNS) to GB suggested that several species could pose a risk of future successful invasion of GB coastal waters, within the next 30 years. This was principally based on the environmental tolerances of NNS. If established the impacts which NNS could impose on GB include similar impacts to native harmful species as well as a higher risk of environmental damage. Experimental work with a high-risk potential invasive species, Ostreopsis cf. ovata, indicated that this impact could be acute, with rapid mortalities observed in exposed naïve GB mussels.
Taken together this body of work shows the validity of chemotaxonomic assessment of toxin profiles as an additional tool for the tracking of harmful microalgal species as well as proactively assessing the risk and impacts which climate change might have for the future impacts of harmful marine microalgal species around GB
Framing God: Toward a Cognitive Account of Religious Rhetoric
The thesis develops a theory of religion based on social cognition and rhetoric
Towards a generalized theory of low-frequency sound source localization
Low-frequency sound source localization generates considerable amount of disagreement between audio/acoustics researchers, with some arguing that below a certain frequency humans cannot localize a source with others insisting that in certain cases localization is possible, even down to the lowest audible of frequencies. Nearly all previous work in this area depends on subjective evaluations to formulate theorems for low-frequency localization. This, of course, opens the argument of data reliability, a critical factor that may go some way to explain the reported ambiguities with regard to low-frequency localization. The resulting proposal stipulates that low-frequency source localization is highly dependent on room dimensions, source/listener location and absorptive properties. In some cases, a source can be accurately localized down to the lowest audible of frequencies, while in other situations it cannot. This is relevant as the standard procedure in live sound reinforcement, cinema sound and home-theater surround sound is to have a single mono channel for the low-frequency content, based on the assumption that human’s cannot determine direction in this band. This work takes the first steps towards showing that this may not be a universally valid simplification and that certain sound reproduction systems may actually benefit from directional low-frequency content
Global consensus Monte Carlo
To conduct Bayesian inference with large data sets, it is often convenient or
necessary to distribute the data across multiple machines. We consider a
likelihood function expressed as a product of terms, each associated with a
subset of the data. Inspired by global variable consensus optimisation, we
introduce an instrumental hierarchical model associating auxiliary statistical
parameters with each term, which are conditionally independent given the
top-level parameters. One of these top-level parameters controls the
unconditional strength of association between the auxiliary parameters. This
model leads to a distributed MCMC algorithm on an extended state space yielding
approximations of posterior expectations. A trade-off between computational
tractability and fidelity to the original model can be controlled by changing
the association strength in the instrumental model. We further propose the use
of a SMC sampler with a sequence of association strengths, allowing both the
automatic determination of appropriate strengths and for a bias correction
technique to be applied. In contrast to similar distributed Monte Carlo
algorithms, this approach requires few distributional assumptions. The
performance of the algorithms is illustrated with a number of simulated
examples
Repository as a service (RaaS)
In his oft-quoted seminal paper ‘Institutional Repositories: Essential Infrastructure For Scholarship In The Digital Age’ Clifford Lynch (2003) described the Institutional Repository as “a set of services that a university offers to the members of its community for the management and dissemination of digital materials created by the institution and its community members.” This paper seeks instead to define the repository service at a more primitive level, without the specialism of being an ‘Institutional Repository’, and looks at how it can viewed as providing a service within appropriate boundaries, and what that could mean for the future development of repositories, our expectations of what repositories should be, and how they could fit into the set of services required to deliver an Institutional Repository service as describe by Lynch.<br/
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