An approximate analytical solution of the radiative transfer equation in hydrometeors accounting for scattering effects

An iterative method for the radiative transfer equation solution is suggested for the scattering hydrometeors. The method allows to find the layer scattering indicatrix. The method is shown to be more general as compared with the four-flux theory or the perturbation method and differs strongly from these ones because even in the case of the first iteration it gives the results which are very close to ones obtained by numerical methods for all rain scattering angles.     

Enhanced Lanthanide Luminescence Using Silver Nanostructures: Opportunities for a New Class of Probes with Exceptional Spectral Characteristics

The photophysical effects of europium tetracycline immobilized in thin polyvinyl alcohol films coated onto silver nanostructures have been investigated. Complimentary to recent reports from our laboratories that the close proximity of luorophores to silver nanostructures can enhance their intrinsic radiative decay rate, we show that up to a 16-fold enhancement in lanthanide luminescence is possible, accompanied by a notable reduction in luminescence lifetime. These results suggest the potential future development of a new class of significantly brighter lanthanide based probes with exceptional spectral properties, which can probably undergo significantly more excitation–emission event cycles due to the reduced lifetime, substantially increasing detectability.     

类Ne铜离子双电子复合过程辐射跃迁几率的MCDF计算

在组态相互作用的ｊ－ｊ耦合下，用相对论多组态Ｄｉｒａｃ－Ｆｏｃｋ（ＭＣＤＦ）方法计算类Ｎｅ铜离子（２９Ｃｕ１９＋）双电子复合过程的辐射跃迁几率。在计算中涉及了大量的双激发态的和单激发态的相对论组态函数，得出了所有可能的跃迁几率，精选得出最可能的跃迁结果。文中所使用的相对论ＭＣＤＦ方法克服了其他方法诸如在相对论效应、组态相互作用等方面的缺陷，从而获得了很好的结果。所得的结果可用于进一步计算类Ｎｅ铜离子的双电子复合系数     

Lie Bracket of Vector Fields in Noncommutative Geometry

The aim of this paper is to avoid some difficulties, related with the Lie bracket, in the definition of vector fields in a noncommutative setting, as they were defined by Woronowicz, Schmüdgen-Schüler and Aschieri-Schupp. We extend the definition of vector fields to consider them as derivations of the algebra, through Cartan pairs introduced by Borowiec. Then, using translations, we introduce the invariant vector fields. Finally, the definition of Lie bracket realized by Dubois-Violette, considering elements in the center of the algebra, is also extended to these invariant vector fields.     

Rightfulness of Summation Cut-Offs in the Albedo Problem with Gaussian Fluctuations of the Density of Scatterers

The one-dimensional version of the radiative transfer problem (i.e. the so-called rod model) is analysed with a Gaussian random extinction function (x). Then the optical length X = ₀ ^Ldx(x) is a Gaussian random variable. The transmission and reflection coefficients, T(X) and R(X), are taken as infinite series. When these series (and also when the series representing T ²(X), T ²(X), R(X)T(X), etc.) are averaged, term by term, according to the Gaussian statistics, the series become divergent after averaging. As it was shown in a former paper by the authors (in Acta Physica Slovaca (2003)), a rectification can be managed when a `modified' Gaussian probability density function is used, equal to zero for X > 0 and proportional to the standard Gaussian probability density for X > 0. In the present paper, the authors put forward an alternative, showing that if the m.s.r. of X is sufficiently small in comparison with , the standard Gaussian averaging is well functional provided that the summation in the series representing the variable T ^m-j (X)R ^j (X) (m = 1,2,..., j = 1,...,m) is truncated at a well-chosen finite term. The authors exemplify their analysis by some numerical calculations.     

Silver Fractal-Like Structures for Metal-Enhanced Fluorescence: Enhanced Fluorescence Intensities and Increased Probe Photostabilities

Substantial increases in fluorescence emission from fluorophore-protein–coated fractal-like silver structures have been observed. We review two methods for silver fractal structure preparation, which have been employed and studied. The first, a roughened silver electrode, typically yielded a 100-fold increase in fluorophore emission, and the second, silver fractal-like structures grown on glass between two silver electrodes, produced a 500-fold increase. In addition, significant increases in probe photostability were observed for probes coated on the silver fractal like structures. These results further serve to compliment our recent work on the effects of nobel metal particles with fluorophores, a relatively new phenomenon in fluorescence we have termed both metal-enhanced fluorescence [1] and radiative decay engineering [2,3]. These results are explained by the metallic surfaces modifying the radiative decay rate () of the fluorescent labels. We believe that this new silver-surface preparation, which results in ultrabright and photostable fluorophores, offers a new generic technology platform for increased fluorescence signal levels, with widespread potential applications to the analytical sciences, imaging, and medical diagnostics.     

Lie Brackets on Affine Bundles

Natural affine analogs of Lie brackets on affine bundles are studied.In particular, a close relation to Lie algebroids and a duality withcertain affine analog of Poisson structure is established as well asaffine versions of complete lifts and Cartan exterior calculi.     

Radiative decays of charged leptons in arbitrary order

In radiative decays of charged leptons induced by non-degenerate neutrino masses and consequent lepton flavour-mixing, the dominant suppression factor at the 1-loop level is (Σ m _a ² )/m _W ² ,m _a being the mass of theath neutrino. We show that this suppression factor is presentin all orders in a class of models including the standard model.     

类钠铁离子的辐射跃迁几率

本文在多组态Dirac-Fock理论框架下计算了类钠铁离子的能级及各能级n_il_i-n_kl_k,(n_i≤5,n_k≤15)间的电偶极辐射跃迁几率,证实了我们发现的新规律:在一个里德伯线系内,当上能级主量子数足够大之后,其跃迁几率仅与主量子数(不是等效主量子数)的三次方成反比。     

On Dirac's quantization condition

The consequences of Dirac's quantization condition are discussed. Observing that this condition generally leads to contradiction and that the normal explanation to resolve the contradiction seems unsatisfactory, we propose a modified quantization condition. It is shown that operator ordering ambiguity could be represented as the arbitrariness of the distribution functions in the modified condition.