Universal relations between nongaussian fluctuations in heavy-ion collisions

We show that universality near a critical end point implies a characteristic relation between third- and fourth-order baryon susceptibilities $\chi_3$ and $\chi_4$, resulting in a banana-shaped loop when $\chi_4$ is plotted as a function of $\chi_3$ along a freeze-out line. Including the individual enhancements of $\chi_3$ and $\chi_4$ near a critical point, these features may be a consistent set of observations supporting the interpretation of baryon fluctuations data as arising from criticality.Comment: 5 pages, 6 figures, revtex style; v2 as publishe

Two-dimensional small-world networks: navigation with local information

Navigation process is studied on a variant of the Watts-Strogatz small world network model embedded on a square lattice. With probability $p$, each vertex sends out a long range link, and the probability of the other end of this link falling on a vertex at lattice distance $r$ away decays as $r^{-\alpha}$. Vertices on the network have knowledge of only their nearest neighbors. In a navigation process, messages are forwarded to a designated target. For $\alpha <3$ and $\alpha \neq 2$, a scaling relation is found between the average actual path length and $pL$, where $L$ is the average length of the additional long range links. Given $pL>1$, dynamic small world effect is observed, and the behavior of the scaling function at large enough $pL$ is obtained. At $\alpha =2$ and 3, this kind of scaling breaks down, and different functions of the average actual path length are obtained. For $\alpha >3$, the average actual path length is nearly linear with network size.Comment: Accepted for publication in Phys. Rev.

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_ DH5&#x3b1;, 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 &#xff08;MC-RR&#xff09;and microcystin-LR&#xff08;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_