Branching Ratio and Polarization of B→ρ(ω)ρ(ω)B\to\rho(\omega)\rho(\omega) Decays in Perturbative QCD Approach

In this work, we calculated the branching ratios, polarization fractions and CP asymmetry of decay modes $B\to\rho(\omega)\rho(\omega)$ in the Perturbative QCD approach, which is based on $\mathbf{k}_T$ factorization. After calculation, we find the the branching ratios of $B^0 \to \rho^+ \rho^-$, $B^+ \to \rho^+ \rho^0$ and $B^+ \to \rho^+ \omega$ are at the order of $10^{-5}$, and their longitudinal polarization fractions are more than 90%. The above results agree with BarBar's measurements. We also predict the branching ratios and polarizations of $B^0 \to \rho^0 \rho^0$, $B^0 \to \rho^0 \omega$ and $B^0 \to \omega \omega$, which will be measured in future. We predicted the CP asymmetry of $B^0 \to \rho^+ \rho^-$ and $B^+ \to \rho^+ \rho^0$, which will play important role in determining angle $\alpha$.Comment: 13 pages, 4 figure

1-Cyano­methyl-4-aza-1-azonia­bicyclo­[2.2.2]octane bromide dihydrate

In the crystal structure of the title compound, C8H14N3 +·Br−·2H2O, inter­molecular O—H⋯O and O—H⋯Br hydrogen bonding occurs. The water mol­ecules are connected into chains extending in the a-axis direction. The bromide anions are connected to the water mol­ecules, forming 10-membered rings. The cations are connected to the anions via weak C—H⋯Br inter­actions. Two carbon atoms of the cation are disordered and were refined using a split model (occupancy ratio 0.70:0.3)

1-Cyano­meth­yl-1,4-diazo­niabicyclo­[2.2.2]octane tetra­bromidocuprate(II)

In the crystal structure of the title complex, (C8H15N3)[CuBr4], the Cu atom is coordinated by four bromido ligands within a strongly distorted tetra­hedron. The anions and cations are connected by weak N—H⋯Br and C—H⋯Br hydrogen-bonding inter­actions

(1R,2S,3R,5S)-5-(1H-Benzimidazol-2-yl)cyclo­hexane-1,2,3,5-tetraol mono­hydrate

In the crystal structure of the title compound, C13H16N2O4·H2O, inter­molecular N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds form an extensive three-dimensional network, consolidating the crystal packing. The cyclo­hexane ring adopts a chair conformation

Second Language Acquisition of Chinese Verb-Noun Collocations

This study aims to investigate the acquisition of verb-noun collocations in Chinese by learners who study Chinese as a foreign language. By conducting a survey, this research attempt to discuss the following issues. 1) Does learners’ acquisition of verb-noun collocations increase with years of learning? 2) Is learners’ acquisition of verb-noun collocations related to the usage frequency of the verbs? 3) Are there any differences between patient objects and non-patient objects in verb-noun collocation acquisitions? 4) Does natural L2 exposure have an impact on collocational competence? Seven verbs are selected in this study, 看 kan, 开 kai, 做 zuo, 走 zou, 放 fang, 打 da, 带 dai. In order to answer the research questions, a survey which consisted of four parts was conducted. This survey was done in a public university in Massachusetts, USA. In total, 82 Chinese learners have participated in this study, and they were grouped into three instructional levels: Second-Year Chinese learners, Third-Year Chinese learners, and Fourth-Year Chinese learners. The data in this research show that the use of collocations is related to learners’ language proficiency, and this study has identified a hook-shaped learning curve in the acquisition of verb-noun collocations. In addition, the frequency is significant to the verb-noun acquisition, and the usage frequency of verbs plays a vital role compared to nouns. Furthermore, at all three proficiency levels, learners had a higher accuracy rate with regard to patient objects in verb-noun collocations. Collocations are problematic for learners who study Chinese as their foreign language; thus, it is essential for instructors to discuss effective teaching methodology for collocations. In this paper, some implications for teaching Chinese verb-noun collocations are provided by the researcher

Analysis and evaluation of the entropy indices of a static network structure

Although degree distribution entropy (DDE), SD structure entropy (SDSE), Wu structure entropy (WSE) and FB structure entropy (FBSE) are four static network structure entropy indices widely used to quantify the heterogeneity of a complex network, previous studies have paid little attention to their differing abilities to describe network structure. We calculate these four structure entropies for four benchmark networks and compare the results by measuring the ability of each index to characterize network heterogeneity. We find that SDSE and FBSE more accurately characterize network heterogeneity than WSE and DDE. We also find that existing benchmark networks fail to distinguish SDSE and FBSE because they cannot discriminate local and global network heterogeneity. We solve this problem by proposing an evolving caveman network that reveals the differences between structure entropy indices by comparing the sensitivities during the network evolutionary process. Mathematical analysis and computational simulation both indicate that FBSE describes the global topology variation in the evolutionary process of a caveman network, and that the other three structure entropy indices reflect only local network heterogeneity. Our study offers an expansive view of the structural complexity of networks and expands our understanding of complex network behavior.The authors would like to thank the financial support of the National Natural Science Foundation of China (71501153), Natural Science Foundation of Shaanxi Province of China (2016JQ6072), and the Foundation of China Scholarship Council (201506965039, 201606965057). (71501153 - National Natural Science Foundation of China; 2016JQ6072 - Natural Science Foundation of Shaanxi Province of China; 201506965039 - Foundation of China Scholarship Council; 201606965057 - Foundation of China Scholarship Council)Published versio