IBDV particles packaged with only segment A dsRNA

AbstractMulti-segmented dsRNA viruses have been suggested to utilize cis-acting elements in the plus-strand RNA to accomplish genomic RNA assortment during viral packaging. It is not clear if bi-segmented dsRNA birnavirus uses the same strategy. By applying a reverse genetic technique, we generated IBDV particles packaged with only segment A by co-transfection DF-1 cells of cDNA from segment A and VP1 (without 5′ and 3′ noncoding region of segment B) supporting random assortment mechanism and indicating the packaging elements of segment B include sequences in the 5′ and 3′ NCR. However, gfp-containing IBDV could not be generated in the presence of gfp cDNA constructs flanked by 5′ and 3′ NCR from segment A or segment B. The data suggest additional packaging signals are required for IBDV genomic packaging. The presence of VP1 protein in the IBDV-A particles also suggests the formation of ribonucleoprotein (RNP) complexes might be involved in the assembly of viral particles

A Trusted-based Cloud Computing Virtual Storage System and Key Technologies

With the popularity of Cloud Computing, people become incresingly concern about security problems, especially the data security, which has become the biggest obstacle for the development of Cloud Computing. In order to protect confidentiality and integrity of user data in Cloud Computing, this paper firstly studies the relevant research works in fields of trusted computing and Cloud Computing data protection and secondly introduces the concept of trusted into Cloud Computing data protection, presents the concept of Trusted Virtual Block Storage Device (TVBSD) and designs the Trusted Cloud Computing Virtual Storage System (TCCVSS). And then, the key technologies such as isolation, block device encryption and two-way authentication are expounded in this paper. Finally, the result of experiments shows that the system and the related technologies can not only effectively ensure the security of user data, but also control the consequent performance overhead in a proper range

Bc→J/ψB_c \to J/\psi helicity form factors and the Bc+→J/ψ+(P,V,ℓ+νℓ)B_c^+ \to J/\psi+(P, V, \ell^+ \nu_\ell) decays

In this paper, we calculate the $B_c\to J/\psi$ helicity form factors (HFFs) up to twist-4 accuracy by using the light-cone sum rules (LCSR) approach. After extrapolating those HFFs to the physically allowable $q^2$ region, we investigate the $B^+_c$-meson two-body decays and semi-leptonic decays $B_c^+ \to J/\psi+(P, V, \ell^+ \nu_\ell)$ with $P/V$ stands for light pseudoscalar/vector meson, respectively. The branching fractions can be derived by using the CKM matrix element and the $B_c$ lifetime from the Particle Data Group, and we obtain ${\cal B}(B_c^+ \to J/\psi \pi^+)=(0.136^{+0.002}_{-0.002})\%$, ${\cal B}(B_c^+ \to J/\psi K^+)=(0.010^{+0.000}_{-0.000})\%$, ${\cal B}(B_c^+ \to J/\psi \rho^+) =(0.768^{+0.029}_{-0.033})\%$, ${\cal B}(B_c^+ \to J/\psi K^{\ast +})=(0.043^{+0.001}_{-0.001})\%$, ${\cal B}(B_c^+ \to J/\psi \mu^+\nu_\mu)=(2.802^{+0.526}_{-0.675})\%$ and ${\cal B}(B_c^+ \to J/\psi \tau^+\nu_\tau)=(0.559^{+0.131}_{-0.170})\%$. We then obtain ${\cal R}_{\pi^+/\mu^+\nu_\mu} = 0.048^{+ 0.009}_{-0.012}$ and ${\cal R}_{K^+ / \pi^+} = 0.075^{+0.005}_{-0.005}$, which agree with the LHCb measured value within $1\sigma$-error. We also obtain ${\cal R}_{J/\psi}=0.199^{+ 0.060}_{-0.077}$, which like other theoretical predictions, is consistent with the LHCb measured value within $2\sigma$-error. Those imply that the HFFs under the LCSR approach are also applicable to the $B^+_c$ meson two-body decays and semi-leptonic decays $B_c^+ \to J/\psi+(P, V, \ell^+ \nu_\ell)$, and the HFFs obtained by using LCSR in a new way implies that there may be new physics in the $B_c\to J/\psi \ell^+ \nu_\ell$ semi-leptonic decays.Comment: 10 pages, 4 figures, published versio

Shearing and Mixing Performance of Ultrahigh-Molecular-Weight Hydrolyzed Polyacrylamide (HPAM) Solution in a Helixes Static Mixer

Static mixers have been widely used to dilute high viscosity, high-molecular-weight polymer mother liquor for polymer flooding, in which the mixing performance plays a critical role. In this work, a novel mixing configuration, named as Helixes static mixer, was proposed to reduce high viscosity degradation rate of polyacrylamide solution resulting from mechanical shear during mixing process. Computational fluid dynamics simulations along with experiments were performed to investigate the mixing process. Several criteria such as the intensity of segregation, mixing distance, pressure loss, and shear strain rate were used to evaluate the mixing and shear performance of static mixers. Compared to the SMX and Kenics static mixer, a longer mixing distance is needed for the Helixes static mixer to achieve an ideal mixture. A lower shear strain rate along with less viscosity degradation rate is obtained in flow field of Helixes static mixer. The spiral-lead and helical directions of mixing elements were optimized to improve mixing performance. Experimental results are in good agreement with the numerical simulations on the intensity of segregation. The viscosity degradation rate of HPAM solution which flows through Helixes static mixer is lower than that of SMX and Kenics static mixers