Cloning and expression of first gene for biodegrading microcystins by Sphingopyxis sp. USTB-05

Harmful cyanobacterial blooms (HCBs) in natural waters are a growing environmental problem worldwide because microcystins (MCs) produced by cyanobacteria are potent hepatotoxins and tumor promoters. MCs are resistant against physical and chemical factors. Thus, biodegradation is the most efficient method for removing MCs, and a number of bacterial strains, especially genus _Sphingomonas_, have been isolated for biodegrading MCs. Although the pathway, enzyme, and gene for biodegrading MCs by _Sphingomonas sp._ have been widely identified recently, no gene concerned with the biodegradation of MCs has been successfully cloned and expressed. In this study, we show that the first and most important gene of mlrA, containing 1,008 bp nucleotides in length, in the biodegradation pathway of MCs by _Sphingopyxis sp._ USTB-05, which encodes an enzyme MlrA containing 336 amino acid residues, is firstly cloned and expressed in _E. coli_ DH5α, with a cloning vector of pGEM-T easy and an expression vector of pGEX-4T-1. The encoded and expressed enzyme MlrA is responsible for cleaving the target peptide bond between 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda) and Arg in the cyclic structure of microcystin-RR （MC-RR）and microcystin-LR（MC-LR), two typical and toxic types of MCs. Linear MC-RR and MC-LR are produced as the first products. These findings are important in constructing a new genetic bacterial strain for the efficient removal of MCs from the important water supplies and resolving the controversy on the biodegradation pathway of different types of MCs by genus _Sphingomonas_

Shear Viscosity of a Gluon Plasma in Perturbative QCD

We calculate the shear viscosity $\eta$ to entropy density $s$ ratio $\eta /s$ of a gluon plasma in kinetic theory including the gg->gg and ggggg processes. Due to the suppressed contribution to $\eta$ in the gg->gg forward scattering, it is known that the gluon bremsstrahlung ggggg process also contributes at the same order $O(\alpha_{s}^{-2})$ in perturbative QCD. Using the Gunion-Bertsch formula for the ggggg matrix element which is valid for the limit of soft bremsstrahlung, we find that the result is sensitive to whether the same limit is taken for the phase space. Using the exact phase space, the ggggg contribution becomes more important to $\eta$ than gg->gg for $\alpha_{s}\gtrsim 2\times 10^{-3}$. Therefore, at $\alpha_{s}=0.1$, $\eta /s\simeq 1.0$, between 2.7 obtained by Arnold, Moore and Yaffe (AMY) and 0.5 obtained by Xu and Greiner. If the soft bremsstrahlung limit is imposed on the phase space such that the recoil effect from the bremsstrahlung gluon is neglected, then the correction from the ggggg process is about 10-30% of the total which is close to AMY's prediction. This shows that the soft bremsstrahlung approximation is not as good as previously expected.Comment: RevTex 4, 14 pages, 3 figures; The results for the soft bremsstrahlung limit for the phase space are added. The difference between AMY and XG approach is addressed with more clarificatio

How Perfect a Gluon Plasma Can Be in Perturbative QCD?

The shear viscosity to entropy density ratio, \eta /s, characterizes how perfect a fluid is. We calculate the leading order \eta /s of a gluon plasma in perturbation using the kinetic theory. The leading order contribution only involves the elastic gg -> gg (22) process and the inelastic ggggg (23) process. The Hard-Thermal-Loop (HTL) treatment is used for the 22 matrix element, while the exact matrix element in vacuum is supplemented by the gluon Debye mass insertion for the 23 process. Also, the asymptotic mass is used for the external gluons in the kinetic theory. The errors from not implementing HTL and the Landau-Pomeranchuk-Migdal effect in the 23 process, and from the uncalculated higher order corrections, are estimated. Our result for \eta /s lies between that of Arnold, Moore and Yaffe (AMY) and Xu and Greiner (XG). Our result shows that although the finite angle contributions are important at intermediate \alpha_s (\alpha_s \sim 0.01-0.1), the 22 process is still more important than 23 when \alpha_s < 0.1. This is in qualitative agreement with AMY's result. We find no indication that the proposed perfect fluid limit \eta /s \simeq 1/(4\pi) can be achieved by perturbative QCD alone.Comment: ReVTex 4, 11 pages, 5 figures. A coding error in the exact matrix element for the 23 process is corrected. Results in Fig. 2,3 and Table I are re-calculated, and relevant discussions are adjusted. Part of the conclusion is change

Fresh Multiple Access: A Unified Framework Based on Large Models and Mean-Field Approximations

Information freshness has attracted increasingly attention in the past decade as it plays a critical role in the emerging real-time applications. Age of information (AoI) holds the promise of effectively characterizing the information freshness, hence widely considered as a fundamental performance metric. However, in multiple-device scenarios, most existing works focus on the analysis and optimization of AoI based on queueing systems. The study for a unified approach for general multiple access control scheme in freshness-oriented scenarios remains open. In this paper, we take into consideration the combination of the fundamental freshness metric AoI and multiple access control schemes to achieve efficient cross-layer analysis and optimization in freshness-oriented scenarios, which is referred to as fresh multiple access. To this end, we build a unified framework with a discrete-time tandem queue model for fresh multiple access. The unified framework enables the analysis and optimization for general multiple access protocols in fresh multiple access. To handle the high dimension framework embedded in fresh multiple access, we introduce large model approaches for the Markov chain formulation in AoI oriented scenarios. Two typical AoI-based metric are studied including age of incorrect information (AoII) and peak AoII. Moreover, to address the computational complexity of the large model, we present mean-field approximations which significantly reduces the dimension of the Markov chain model by approximating the integral affect of massive devices in fresh multiple access.Comment: accepted by Journal of Communications and Network

Raise Management Standards of Property Tax on Transnational Corporations

As China joined WTO, more and more foreign multinational companies will enter China. They run enterprises within the territory of China. This will inevitably play an active role in promoting the economic construction of China. But we should pay attention to some foreign multinational companies in China that often reduce the incomes of Chinese branch companies by utilizing transfer prices. Thus they achieve the goal of evading payment of duty. These make the tax revenue of Chinese Government fall sharply. So it is very important to raise management level of property tax to the multinational companies. This text explains the loss caused by the foreign businessmen using improper means to transfer prices. They import raw materials at a high price and export the products at a low price. Also the corresponding measures are made out in this paper. Key words: Multinational companies, Import at a high price and export at a low price, Current capital, Transfer prices Résumé: Avec l’adhésion de la Chine à l’OMC, de plus en plus nombreux sont les entreprises transnationales qui s’investiraient en Chine. Cela poussera inévitablement la construction économique de la Chine. Néanmoins, nons devons noter que, actuellement, des entreprises étrangères en Chine diminuent les profits des filiales chinoise en transférant les prix et atteint ainsi leur but d’éviter la taxe. De cet effet, les recettes fiscales de la Chine diminuent considérablement. Donc, il est très important d’améliorer le viveau de gestion fiscale à l’égard des entreprises transnationales. Cet article expose d’abord le déficit provoqué par les actions malhonnêtes de commerçants étrangers qui transfèrent les prix avec des moyens illégitimes pour acheter les ressources productives à haut prix et vendre les produits à bas prix, et propose ensuite des contre-mesures. Mots-Clés: entreprise transnationale, acheter cher et vendre moins cher, fonds liquide

Coercive Region-level Registration for Multi-modal Images

We propose a coercive approach to simultaneously register and segment multi-modal images which share similar spatial structure. Registration is done at the region level to facilitate data fusion while avoiding the need for interpolation. The algorithm performs alternating minimization of an objective function informed by statistical models for pixel values in different modalities. Hypothesis tests are developed to determine whether to refine segmentations by splitting regions. We demonstrate that our approach has significantly better performance than the state-of-the-art registration and segmentation methods on microscopy images.Comment: This work has been accepted to International Conference on Image Processing (ICIP) 201