Some Unusual Properties of Turbulent Convection and Dynamos in Rotating Spherical Shells

The dynamics of convecting fluids in rotating spherical shells is governed at Prandtl numbers of the order unity by the interaction between differential rotation and roll-like convection eddies. While the differential rotation is driven by the Reynolds stresses of the eddies, its shearing action inhibits convection and causes phenomena such as localized convection and turbulent relaxation oscillations. The response of the system is enriched in the case of dynamo action. Lorentz forces may brake either entirely or partially the geostrophic differential rotation and give rise to two rather different dynamo states. Bistability of turbulent dynamos exists for magnetic Prandtl numbers of the order unity. While the ratios between mean magnetic and kinetic energies differ by a factor of 5 or more for the two dynamo states, the mean convective heat transports are nearly the same. They are much larger than in the absence of a magnetic field.Comment: To appear in Procs. IUTAM Symposium on Turbulence in the Atmosphere and Oceans, 08-7 = GA.06-0

Patterns of convection in rotating spherical shells

Patterns of convection in internally heated, self-gravitating rotating spherical fluid shells are investigated through numerical simulations. While turbulent states are of primary interest in planetary and stellar applications the present paper emphasizes more regular dynamical features at Rayleigh numbers not far above threshold which are similar to those which might be observed in laboratory or space experiments. Amplitude vacillations and spatial modulations of convection columns are common features at moderate and large Prandtl numbers. In the low Prandtl number regime equatorially attached convection evolves differently with increasing Rayleigh number and exhibits an early transition into a chaotic state. Relationships of the dynamical features to coherent structures in fully turbulent convection states are emphasized

Novel imino sugar α-glucosidase inhibitors as antiviral drugs

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Selection of the biological activity of DNJ neoglycoconjugates through click length variation of the side chain.

A series of neoglycoconjugates derived from deoxynojirimycin has been prepared by click connection with functionalised adamantanes. They have been assayed as glycosidase inhibitors, as inhibitors of the glycoenzymes relevant to the treatment of Gaucher disease, as well as correctors of the defective ion-transport protein involved in cystic fibrosis. We have demonstrated that it is possible to selectively either strongly inhibit ER-α-glucosidases and ceramide glucosyltransferase or restore the activity of CFTR in CF-KM4 cells by varying the length of the alkyl chain linking DNJ and adamantane