Nature of X(3872)X(3872) from its radiative decay

We study the radiative decay of $X(3872)$ based on the assumption that $X(3872)$ is regarded as a $c\overline{c}$ charmonium with quantum number $J^{PC}=1^{++}$ ($J,\,P,\,C$ stand for spin, parity and charge conjugation, respectively) in accordance with the Particle Data Group assignment. The form factors of $X(3872)$ transitions to $J/\psi\gamma$ and $\psi'\gamma$ ($\psi'$ denotes $\psi(2S)$ throughout the paper) are calculated in the framework of the covariant light-front quark model. The phenomenological wave function of a meson depends on the parameter $\beta$ which inverse essentially describes the confinement scale. In the present work, the parameters $\beta$ for the vector $J/\psi$ and $\psi'$ mesons will be determined through their decay constants which are from the experimental values of their partial decay widths to electron-positron pair. As for $X(3872)$ we determine the value of $\beta$ by the decay width of $X(3872)\rightarrow \psi'\gamma$. Then we examine the width of $X(3872)\to J/\psi\gamma$ in a manner of parameter-free prediction and confront it with the experimental value. Both of the hypothesises that $X(3872)$ is the $1P$ state or $2P$ state are considered, although the predicted $1P$ charmonium mass is significantly lower than the mass of $X(3872)$. It is found that one will encounter the inconsistency or contradiction between the widths of $X(3872)\to J/\psi\gamma$ and $X(3872)\to \psi'\gamma$ if interpreting $X(3872)$ as a pure charmonium. We thus conclude that $X(3872)$ can not be a pure $c\overline c$ resonance and other components are necessary in its wave function.Comment: 12 pages, 1 figur

Characterizing exons 11 and 1 promoters of the mu opioid receptor (Oprm) gene in transgenic mice

BACKGROUND: The complexity of the mouse mu opioid receptor (Oprm) gene was demonstrated by the identification of multiple alternatively spliced variants and promoters. Our previous studies have identified a novel promoter, exon 11 (E11) promoter, in the mouse Oprm gene. The E11 promoter is located ~10 kb upstream of the exon 1 (E1) promoter. The E11 promoter controls the expression of nine splice variants in the mouse Oprm gene. Distinguished from the TATA-less E1 promoter, the E11 promoter resembles a typical TATA-containing eukaryote class II promoter. The aim of this study is to further characterize the E11 and E1 promoters in vivo using a transgenic mouse model. RESULTS: We constructed a ~20 kb transgenic construct in which a 3.7 kb E11 promoter region and an 8.9 kb E1 promoter region controlled expression of tau/LacZ and tau/GFP reporters, respectively. The construct was used to establish a transgenic mouse line. The expression of the reporter mRNAs, determined by a RT-PCR approach, in the transgenic mice during embryonic development displayed a temporal pattern similar to that of the endogenous promoters. X-gal staining for tau/LacZ reporter and GFP imaging for tau/GFP reporter showed that the transgenic E11 and E1 promoters were widely expressed in various regions of the central nervous system (CNS). The distribution of tau/GFP reporter in the CNS was similar to that of MOR-1-like immunoreactivity using an exon 4-specific antibody. However, differential expression of both promoters was observed in some CNS regions such as the hippocampus and substantia nigra, suggesting that the E11 and E1 promoters were regulated differently in these regions. CONCLUSION: We have generated a transgenic mouse line to study the E11 and E1 promoters in vivo using tau/LacZ and tau/GFP reporters. The reasonable relevance of the transgenic model was demonstrated by the temporal and spatial expression of the transgenes as compared to those of the endogenous transcripts. We believe that these transgenic mice will provide a useful model for further characterizing the E11 and E1 promoter in vivo under different physiological and pathological circumstances such as chronic opioid treatment and chronic pain models

Spindle oscillations are generated in the dorsal thalamus and modulated by the thalamic reticular nucleus

Spindle waves occur during the early stage of slow wave sleep and are thought to arise in the thalamic reticular nucleus (TRN), causing inhibitory postsynaptic potential spindle-like oscillations in the dorsal thalamus that are propagated to the cortex. We have found that thalamocortical neurons exhibit membrane oscillations that have spindle frequencies, consist of excitatory postsynaptic potentials, and co-occur with electroencephalographic spindles. TRN lesioning prolonged oscillations in the medial geniculate body (MGB) and auditory cortex (AC). Injection of GABA~A~ antagonist into the MGB decreased oscillation frequency, while injection of GABA~B~ antagonist increased spindle oscillations in the MGB and cortex. Thus, spindles originate in the dorsal thalamus and TRN inhibitory inputs modulate this process, with fast inhibition facilitating the internal frequency and slow inhibition limiting spindle occurrence

Students' acceptance of youtube for procedural learning

This research investigates students' acceptance of YouTube for procedural learning. Multiple regression was used to analyze the data based on sample of 240 respondents who pursuing studies in a public higher learning institution in Federal Territory of Labuan, Malaysia. Results revealed that there is connection between content richness, task-technology fit, YouTube self-efficacy and vividness and behavioral intention to use YouTube. Results may enhance the intentions of users on browsing YouTube for more procedural learning. YouTube can enlarge the functions as a mass-oriented means for procedural learning to increase the perceived usefulness of YouTube and improve the users' behavioral intention to browse YouTube. The role of this study is important to dedicate the YouTube users for the procedural learning in their education tasks. This study is to integrate the TAM with perceived ease of use and perceived usefulness to have an effect on the activity intention of users

Visualizing topological edge states of single and double bilayer Bi supported on multibilayer Bi(111) films

Freestanding single-bilayer Bi(111) is a two-dimensional topological insulator with edge states propagating along its perimeter. Given the interlayer coupling experimentally, the topological nature of Bi(111) thin films and the impact of the supporting substrate on the topmost Bi bilayer are still under debate. Here, combined with scanning tunneling microscopy and first-principles calculations, we systematically study the electronic properties of Bi(111) thin films grown on a NbSe2 substrate. Two types of non-magnetic edge structures, i.e., a conventional zigzag edge and a 2x1 reconstructed edge, coexist alternately at the boundaries of single bilayer islands, the topological edge states of which exhibit remarkably different energy and spatial distributions. Prominent edge states are persistently visualized at the edges of both single and double bilayer Bi islands, regardless of the underlying thickness of Bi(111) thin films. We provide an explanation for the topological origin of the observed edge states that is verified with first-principles calculations. Our paper clarifies the long-standing controversy regarding the topology of Bi(111) thin films and reveals the tunability of topological edge states via edge modifications.Comment: 36 pages, 10 figure

Study of Bs→πρB_{s}\to \pi \rho decays in the perturbative QCD approach

In this note, we calculate the branching ratio and CP asymmetry parameters of $B_s\to\pi\rho$ in the framework of perturbative QCD approach based on $k_T$ factorization. This decay can occur only via annihilation diagrams in the Standard Model. We find that (a)the charge averaged $Br(B_s\to\pi^{+}\rho^{-}+\pi^{-}\rho^{+})$ is about $(9-12)\times10^{-7}$; $Br(B_s\to\pi^{0}\rho^{0}) \simeq 4\times10^{-7}$; and (b) there are sizable CP asymmetries in the processes, which can be tested in the near future Large Hadron Collider beauty experiments (LHC-b) at CERN or BTeV experiments at Fermilab.Comment: 6 pages, 3 figure