Quantum cosmology in 2+1 and 3+1 dimensions

We study the Wheeler-DeWitt equations for the wave function of the universe in 2+1 and 3+1 dimensions. Perturbation methods are developed and the first few orders areexplicitly calculated for the case of an inflating universe. We find that early quantum fluctuation can produce large-scale inhomogenities in the global structure of the universe at later times.     

TCP, quantum gravity,the cosmological constant and all that...

We study cosmology from the point of view of quantum gravity. Some light is thrown on the nature of time, and it is suggested that the cosmological arrow of time is generated by a spontaneous breakdown of TCP. Conventional cosmological models in which quantum fields interact with a time-dependent gravitational field are shown to describe an approximation to the quantum gravitational wave function which is valid in the long-wavelength limit. Two problems with initial conditions are resolved in models in which a negative bare cosmological constant is cancelled by the classical excitation of a Bose field η with a very flat potential. These models can also give a natural explanation for the observed value of the cosmological constant.     

The flow of an electrically conducting fluid at a rear stagnation point

Summary We consider the impulsively generated magnetohydrodynamic flow at a rear stagnation point. The work of Leibovich is carried further by formulating the inner viscous problem and providing analytical solutions and complete numerical solutions for the entire range of the interaction parameter. It is shown that the present results are consistent with previously obtained numerical solutions to the steady equations of both similarity and non-similarity form.

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Résumé Nous considérons l'écoulement magneto-hydrodynamique impulsivement engendré à un point de stagnation arrière. On porte plus loin l'étude de Leibovich par la formulation du problème visqueux intérieur et en fournissant des solutions analytiques et numériques complètes correspondantes au champ entier du paramètre d'interaction. On montre que les résultats actuels sont en accord avec les solutions numériques, et de similitude et de non-similitude, déjà connues des équations stationnaires.

     

On the electric current from electrodes in a magnetized semiconductor film

The problem on the electric current from electrodes in a magnetizedsemiconductor film is reduced to the skew derivative problemfor the Laplace equation outside cuts in a plane. The problemfor the Laplace equation is studied under different conditionsat infinity, which have a certain physical meaning. With thehelp of potential theory, the skew derivative problem is reducedto a Fredholm integral equation of the second kind, which isuniquely solvable. The Neumann problem for the Laplace equationin the exterior of cuts in a plane is a particular case of ourproblem.     

阻抗谱法确定扩散系数

给出了阻抗谱法确定扩散系数的理论和方法;以钒酸盐阴极材料Na_(1+x)V_3O_(?)(L.T.)为例,应用本方法计算给出了Li~+在阴极中的扩散系数为10~(?)-10~(-9)cm~2·s~(-1);最后还对误差来源进行了讨论. 关键词：     

Studies in azide chemistry. Part X [1]. Synthesis of perfluoro-2-azido-1-azacyclohexene

Perfluoro-2-azido-1-azacyclohexene can be prepared by treating perfluoro-1-azacyclohexene with an equimolar proportion of sodium azide (in acetonitrile) or azidotrimethylsilane under mild conditions; ¹⁹F n.m.r. analysis reveals that this new imidoyl azide participates in ring ° chain valence tautomerism, the tetrazolo-isomer constituting 19% of the equilibrium mixture at 35 °C.     

Chromatographic resolution of racemic amines,carboxylic acids,and alcohols by a new homochiral reagent derived fromendo-borneol

Summary Chromatographic separation of racemic amines, carboxylic acids and alcohols can be achieved with excellent resolution as measured in terms of the chromatographic separation factor by derivatization with a homochiral oxazolidin-2-one easily prepared in three steps fromendo-borneol. The resolved materials can be isolated in excellent yields by cleavage of the resultant diastereomers using conventional methods, which also allow recovery of the chiral resolving agent for re-use.