Studies of the Initial Steps of Lysine Biosynthesis in E. coli

1. A pUC9 derived plasmid, pDA2, containing the gene encoding for DHDPA synthase was obtained from Dr. P. Stragier in Paris. The E. coli strain MV1190 (RecA-) was transformed by pDA2 to produce an overexpressing strain for DHDPA synthase. The specific activity of this crude extract showed 200-fold more activity than that from the wild-type

Power extraction by a water turbine in inviscid free surface flow with vertical shear

Hydro-kinetic, tidal stream, and ocean current energy turbines operate in flows subject to vertical shear, which has an influence on the turbines, especially ones located near the bed. The gravity applied on a fluid is proportional to its density, thus the static pressure induced by gravity is enhanced by the higher density of water than air. Turbines are expected to be placed in fast moving, shallow flows. Hence the Froude number may be relatively high and changes to the free surface are likely, leading to additional flow confinement. In order to investigate the combined effect of vertical shear and gravity on idealized turbines, an extension of linear momentum actuator disc theory (LMADT) is used to estimate the thrust and power extracted by an idealized turbine for two types of free surface inviscid flow. It is assumed that there is fast pressure recovery and that the core flow contains self-similar velocity profiles. Results from a parameter study in which the velocity profiles and turbine settings are varied show that idealized turbines operate at higher efficiency under the effect of gravity, but operate at either higher or lower efficiency under shear flow. The proposed model can also be used to investigate energy extracted by turbines in a periodically spaced array, enabling better evaluation of array efficiency

Semiclassical almost isometry

Let M be a complex projective manifold, and L an Hermitian ample line bundle on it. A fundamental theorem of Gang Tian, reproved and strengthened by Zelditch, implies that the Khaeler form of L can be recovered from the asymptotics of the projective embeddings associated to large tensor powers of L. More precisely, with the natural choice of metrics the projective embeddings associated to the full linear series |kL| are asymptotically symplectic, in the appropriate rescaled sense. In this article, we ask whether and how this result extends to the semiclassical setting. Specifically, we relate the Weinstein symplectic structure on a given isodrastic leaf of half-weighted Bohr-Sommerfeld Lagrangian submanifolds of M to the asymptotics of the the pull-back of the Fubini-Study form under the semiclassical projective maps constructed by Borthwick, Paul and Uribe.Comment: exposition improve

Tracer Advection in an Idealised River Bend with Groynes

This paper presents numerical simulations of particle advection in the bend of an open channel containing groynes, which is an idealised form of a shallow river bend in a wide river. The flow field is computed using a boundary-fitted solver of the non-orthogonal, curvilinear shallow water equations. The computational grid is generated by solving Poisson-type elliptic partial differential equations using an iterative multi-grid scheme for prescribed boundary coordinates. The shallow water equations are discretised with finite differences in space, and 4th order Runge-Kutta integration in time. Tracers introduced at specific initial locations have their trajectories computed using Lagrangian particle tracking. The numerical shallow flow model is verified by comparison to the analytical solution of fully developed flow in an open channel. The combined shallow flow and Lagrangian particle-tracking model is then used to simulate the advection of tracer particles in a rectangular channel containing a pair of parallel groynes, and tracer particles in a curved open channel containing groynes, of dimensions roughly equivalent to a Danube River bend

Toeplitz operators on symplectic manifolds

We study the Berezin-Toeplitz quantization on symplectic manifolds making use of the full off-diagonal asymptotic expansion of the Bergman kernel. We give also a characterization of Toeplitz operators in terms of their asymptotic expansion. The semi-classical limit properties of the Berezin-Toeplitz quantization for non-compact manifolds and orbifolds are also established.Comment: 40 page

Deficiency and excess of groundwater iodine and their health associations.

More than two billion people worldwide have suffered thyroid disorders from either iodine deficiency or excess. By creating the national map of groundwater iodine throughout China, we reveal the spatial responses of diverse health risks to iodine in continental groundwater. Greater non-carcinogenic risks relevant to lower iodine more likely occur in the areas of higher altitude, while those associated with high groundwater iodine are concentrated in the areas suffered from transgressions enhanced by land over-use and intensive anthropogenic overexploitation. The potential roles of groundwater iodine species are also explored: iodide might be associated with subclinical hypothyroidism particularly in higher iodine regions, whereas iodate impacts on thyroid risks in presence of universal salt iodization exhibit high uncertainties in lower iodine regions. This implies that accurate iodine supply depending on spatial heterogeneity and dietary iodine structure optimization are highly needed to mitigate thyroid risks in iodine-deficient and -excess areas globally