43,728 research outputs found
In situ recovery of secondary metabolites using adsorption resins : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy at Massey University, Palmerston North, New Zealand
Almost without exception a two to three fold increase in microbial secondary metabolite concentration was measured when adsorption resins were added in-situ during a submerged liquid fermentation. Anguidine was produced at a final concentration of 440 mg/L after five days in a shake flask that contained adsorption resin, compared to 300 mg/L without resin. Rapamcyin was produced at a final concentration of 87 mg/L after six days in a shake flask that had resin present, compared to 28 mg/L without resin. Ansamitocin P3 was produced at a final concentration of 24 mg/L after six days in a shake flask with resin, compared to 9.75 mg/L without resin. The increase in secondary metabolite concentration confirmed that the resins used provided a positive influence on secondary metabolite production. Adsorption resins for shake flask studies were selected based on their ability to achieve maximum adsorption of specific secondary metabolites in various fermentation systems. A library of adsorbed concentrations was collected for the three secondary metabolites studied. The lipophilicty of the metabolite, calculated by several software packages, was compared to the polarity of the adsorption resin to generate a relationship. By using the preceding set of data it is possible to select adsorption resins that improved the produced concentrations of the target organic secondary metabolites. The fermentation media compositions tested appeared to have no effect on the final product concentration when adsorption resins were added in situ during the fermentations. Based on the lipohilictiy of the secondary metabolite and the polarity of the resins, it is possible to select a resin that achieves a high adsorption concentration of the target organic secondary metabolite
On the Complexity of Random Quantum Computations and the Jones Polynomial
There is a natural relationship between Jones polynomials and quantum
computation. We use this relationship to show that the complexity of evaluating
relative-error approximations of Jones polynomials can be used to bound the
classical complexity of approximately simulating random quantum computations.
We prove that random quantum computations cannot be classically simulated up to
a constant total variation distance, under the assumption that (1) the
Polynomial Hierarchy does not collapse and (2) the average-case complexity of
relative-error approximations of the Jones polynomial matches the worst-case
complexity over a constant fraction of random links. Our results provide a
straightforward relationship between the approximation of Jones polynomials and
the complexity of random quantum computations.Comment: 8 pages, 4 figure
Doing the business: variegation, opportunity and intercultural experience among intra-EU highly-skilled migrants
Focusing on the working experiences of the French highly skilled in London's financial and business sectors, this paper examines the impact of ongoing pan-European variegation on intra-EU highly skilled migration in two key respects: firstly, in its role as a driver for mobility, through its association with divergent opportunity structures across different nations and regions; and secondly, as a potential obstacle to the successful realization of such opportunities, post migration, where mobility exposes the highly skilled migrant to new and embedded forms of difference. Such differences necessitate adaptations, and the acquisition of new inter-cultural competencies, that go on to mediate the experience, evaluations and outcomes of such opportunity-driven mobilities. In unpacking the particularities associated with the mobilities of specific populations (the French), to specific places (London) we seek to contribute to a people and place-sensitive understanding of the relationship between spatial mobility and social mobility
French connections: the networking strategies of French highly skilled migrants in London
Although the migration studies literature often takes social networks for granted, these social ties are not spontaneous but require effort and nurturing. There has been insufficient research on the actual process of networking, especially among highly skilled migrants. Our understanding of why and how migrants form networks with particular characteristics is still poor. In this article, we argue that it is necessary to consider both the structure and content of networks β the nature of the relationships as well as the flow of resources within various social ties. Drawing on qualitative data from a study of highly skilled French migrants in London's business and financial sector, we use a microanalysis of network-making processes. In the context of London as a dynamic and highly competitive financial centre, we examine the importance of opportunities, skills and shared interests in building new social relationships from scratch. In addition, we also assess how mobility and proximity, virtual communication and co-presence impact on geographically dispersed networks and why some long distance relationships endure while others fade over time. By bringing together classic literature on professional networking and wider discussions on how relationships are managed across time and space, our work contributes to a fuller understanding of why and how highly skilled migrants form networks with particular characteristics
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