CRYSTAL AND MOLECULAR-STRUCTURE OF 8,2'-CYCLOADENOSINE TRIHYDRATE

8,2'-Cycloadenosine, C IoHi~NsO4.3H20, is a modified arabinosyladenosine nucleoside which has been cyclized at the C(8) and 0(2') atoms. THe trihydrate crystallizes in the orthorhombic space group P2~2~2~, with a = 8.680 (2), b = 5.991 (2), c = 27.203 (4) A, Z = 4. The structure was refined to R = 0.0672 for 1411 unique reflections, photographically recorded. The arabinofuranose ring has a flattened C(4')-endo-C(3')- exo pucker. The conformation about C(4')-C(5') is gauche-gauche, and that about the sugar-base bond is high anti. The crystal structure involves extensive base-base hydrogen bonding, N(1), N(6) and N(7) all being participants

Experimental Identification of the Kink Instability as a Poloidal Flux Amplification Mechanism for Coaxial Gun Spheromak Formation

The magnetohydrodynamic kink instability is observed and identified experimentally as a poloidal flux amplification mechanism for coaxial gun spheromak formation. Plasmas in this experiment fall into three distinct regimes which depend on the peak gun current to magnetic flux ratio, with (I) low values resulting in a straight plasma column with helical magnetic field, (II) intermediate values leading to kinking of the column axis, and (III) high values leading immediately to a detached plasma. Onset of column kinking agrees quantitatively with the Kruskal-Shafranov limit, and the kink acts as a dynamo which converts toroidal to poloidal flux. Regime II clearly leads to both poloidal flux amplification and the development of a spheromak configuration.Comment: accepted for publication in Physical Review Letter

Transmission of hand, foot and mouth disease and its potential driving factors in Hong Kong

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On a mechanism for enhancing magnetic activity in tidally interacting binaries

We suggest a mechanism for enhancing magnetic activity in tidally interacting binaries. We suppose that the deviation of the primary star from spherical symmetry due to the tidal influence of the companion leads to stellar pulsation in its fundamental mode. It is shown that stellar radial pulsation amplifies torsional Alfv{\'e}n waves in a dipole-like magnetic field, buried in the interior, according to the recently proposed swing wave-wave interaction (Zaqarashvili 2001). Then amplified Alfv{\'e}n waves lead to the onset of large-scale torsional oscillations, and magnetic flux tubes arising towards the surface owing to magnetic buoyancy diffuse into the atmosphere producing enhanced chromospheric and coronal emission.Comment: Accepted in Ap

Ullemar's formula for the Jacobian of the complex moment mapping

The complex moment sequence m(P) is assigned to a univalent polynomial P by the Cauchy transform of the P(D), where D is the unit disk. We establish the representation of the Jacobian det dm(P) in terms of roots of the derivative P'. Combining this result with the special decomposition for the Hurwitz determinants, we prove a formula for the Jacobian which was previously conjectured by C. Ullemar. As a consequence, we show that the boundary of the class of all locally univalent polynomials in $U$ is contained in the union of three irreducible algebraic surfaces.Comment: 14 pages, submitted for "Complex Variables. Theory and Application

Building ventilation as an effective disease intervention strategy on a large and dense social contact network

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