Limit on the B0-->rho0rho0 branching fraction and implications for the Cabibbo-Kobayashi-Maskawa angle alpha

We search for the decay B0-->rho(0)rho(0) in a data sample of about 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We find no significant signal and set an upper limit of 1.1x10(-6) at 90% C.L. on the branching fraction. As a result, the uncertainty due to penguin contributions on the Cabibbo-Kobayashi-Maskawa unitarity angle alpha measured in B-->rhorho decays is decreased to 11 degrees at 68% C.L.     

基于函数调用图的静态数据分配

在许多嵌入式设计中,数据存储器是稀缺资源.如何基于静态分配方案,用最少的内存空间来存储程序数据成为嵌入式设计中一个非常重要的问题.如果两个函数之间不存在直接或者间接的调用关系的话,这两个函数的局部变量的生命期就没有重叠.这样的两个函数的局部变量可以共用存储空间而不会影响程序的正确性.基于这个思路,本文提出一种基于函数调用图的拓扑排序的最优静态分配算法(TBA)并证明了该分配算法的最优性.该分配算法通过静态分析技术,构建函数调用图(FCG),基于FCG的拓扑排序,计算每个函数的私有数据段的全局地址以及段内每个符号的全局地址,并根据重定位表更新对这些符号的引用.实验结果表明该算法优于前人提出的启发式算法.     

Empirical,Semi-Empirical and Experimental Determination of K X-Ray Fluorescence Parameters of Some Elements in the Atomic Range 21 ≤ Z ≤ 30

In this study, the semi-empirical and empirical calculations of K X-ray intensity ratios, K-shell fluorescence yields, and vacancy transfer probabilities have been performed for 3d transition elements. Also, σ_Kα, σ_Kβ production cross-sections, K_β/K_α intensity ratios, ω_K fluorescence yields, and η_KL vacancy transfer probabilities of 3d transition elements have been measured. The samples were excited by 59.5 keV γ-rays from a ²⁴¹Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.     

EPR of Cu2+-doped Cs2CO3 and CsHCO3: evidence of the Jahn–Teller effect

Cu²⁺-doped Cs₂CO₃ and CsHCO₃ single crystals were investigated by electron paramagnetic resonance between 113–273 and 173–313 K, respectively. For both single crystals, two sites were observed for the Cu²⁺ at ambient temperature for arbitrary orientations of the single crystals in the magnetic field. However, when the temperature is varied, the spectra indicate the equivalence of the two sites at 225 and 240 K for the single crystals, respectively, to the above order. Below and above these temperatures two sites for Cu²⁺ appear, and below 133 and 173 K the signals do not vary and two sites were always observed. This is attributed to the transition of the dynamic Jahn–Teller effect to a static situation at lower temperatures. Cu²⁺ seems to replace Cs⁺ and the charge compensation is fulfilled by another Cs⁺. Spin-Hamiltonian parameters for both single crystals at ambient temperature are reported and discussed.     

Radioactivity measurements and risk assessments of spa waters in some areas in Turkey

The current study presents the results of the activity of radionuclides in spa waters, and evaluates their radiological influences on the population consuming these waters in the Central and Eastern Black Sea regions of Turkey. Since these waters are used for therapy and consumption purposes unconsciously, their radiological impact on the people was computed by taking into consideration the annual intake through ingestion of ²²⁶Ra, ²³²Th, ⁴⁰K, ¹³⁷Cs and ²²²Rn. The mean activities were estimated to be 11.35 for gross alpha, 6.23 for gross beta, 2.96 for ²²⁶Ra, 0.42 for ²³²Th, 0.069 for ¹³⁷Cs, 0.19 for ⁴⁰K, and 267 Bq L^–1 for ²²²Rn, respectively. The estimated effective doses from spa water were found to be 49.77 µSv a^–1 (²²⁶Ra), 5.95 µSv a^–1 (²³²Th), 0.07 µSv a^–1 (¹³⁷Cs), 0.83 µSv a^–1 (⁴⁰K) and 56.03 µSv a^–1 (²²²Rn). These values were evaluated and compared with related verified values from literature. Also, physico-chemical characterizations of spa water samples considered in the current study were investigated. This study would be useful for consumers and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters.     

A particular solution of Heun equation for Hulthen and Woods‐Saxon potentials

In this article a particular solution of Heun equation is derived by making use of the Nikiforov‐Uvarov (NU) method which provides exact solutions for general hypergeometric equation and eigenvalues together with eigenfunctions of the Heun equation for this particular solution are obtained. One to one correspondence (isomorphism) of the aforesaid equation with the radial Schrödinger equation is emphasized and also physical counterparts of the parameters in this equation are put forward by introducing solutions for two different potential functions (Hulthen and Woods‐Saxon potentials).

     

Zeros of the Jones Polynomial for Multiple Crossing-Twisted Links

Let D be a general connected reduced alternating link diagram, C be the set of crossings of D and C′ be the nonempty subset of C. In this paper we first define a multiple crossing-twisted link family {D ⁿ (C′)|n=1,2,…} based on D and C′, which produces (2,2n+1)-torus knot family, the link family A _n defined in Chang and Shrock (Physica A 301:196–218, 2001) and the pretzel link family P(n,n,n) as special cases. Then by applying Beraha-Kahane-Weiss’s Theorem we prove that limits of zeros of Jones polynomials of {D ⁿ (C′)|n=1,2,…} are the unit circle |z|=1 (It is independent of the selections of D and C′) and several isolated limits, which can be determined by computing flow polynomials of subgraphs of G corresponding to D. Furthermore, we use the method of Brown and Hickman (Discrete Math. 242:17–30, 2002) to prove that, for any ε>0, all zeros of Jones polynomial of the link D ⁿ (C) lie inside the circle |z|=1+ε, provided that n is large enough. Our results extend results of F.Y. Wu, J. Wang, S.-C. Chang, R. Shrock and the present authors and refine partial result of A. Champanerkar and L. Kofman.     

Surface enhanced covalency and its effect on the surface states ofd-band metal oxides

The effect of electron-electron interactions on the surface states of ionicd-band oxides is reported. The local density of states of surface cations in the valence band region is significantly increased when surface states occur in the band gap. Coulomb repulsion associated with thissurface enhanced covalency tends to force surface states out of the band gap. These results suggest an explanation of recent experiments on SrTiO₃ and TiO₂.