Quantum Phase Transition in Hall Conductivity on an Anisotropic Kagome Lattice

We study the quantum Hall effect(QHE) on the Kagom\'{e} lattice with anisotropy in one of the hopping integrals. We find a new type of QHE characterized by the quantization rules for Hall conductivity $\sigma_{xy}=2ne^{2}/h$ and Landau Levels $E(n)=\pm v_{F}\sqrt{(n+1/2)\hbar Be}$ ($n$ is an integer), which is different from any known type. This phase evolves from the QHE phase with $\sigma_{xy}=4(n+1/2)e^{2}/h$ and $E(n)=\pm v_{F}\sqrt{2n\hbar Be}$ in the isotropic case, which is realized in a system with massless Dirac fermions (such as in graphene). The phase transition does not occur simultaneously in all Hall plateaus as usual but in sequence from low to high energies, with the increase of hopping anisotropy.Comment: 5 pages, 4 figure

SU(5) Symmetry of spdfg Interacting Boson Model

The extended interacting boson model with s-, p-, d-, f- and g-bosons being included (spdfg IBM) are investigated. The algebraic structure including the generators, the Casimir operators of the groups at the SU(5) dynamical symmetry and the branching rules of the irreducible representation reductions along the group chain are obtained. The typical energy spectrum of the Symmetry is given.Comment: 12 pages, 2 figure

Patterns and influencing factor of synonymous codon usage in porcine circovirus

<p>Abstract</p> <p>Background</p> <p>Analysis of codon usage can reveal much about the molecular evolution of the viruses. Nevertheless, little information about synonymous codon usage pattern of porcine circovirus (PCV) genome in the process of its evolution is available. In this study, to give a new understanding on the evolutionary characteristics of PCV and the effects of natural selection from its host on the codon usage pattern of the virus, Patterns and the key determinants of codon usage in PCV were examined.</p> <p>Methods</p> <p>We carried out comprehensive analysis on codon usage pattern in the PCV genome, by calculating relative synonymous codon usage (RSCU), effective number of codons (ENC), dinucleotides and nucleic acid content of the PCV genome.</p> <p>Results</p> <p>PCV genomes have relatively much lower content of GC and codon preference, this result shows that nucleotide constraints have a major impact on its synonymous codon usage. The results of the correspondence analysis indicate codon usage patterns of PCV of various genotypes, various subgenotypes changed greatly, and significant differences in codon usage patterns of Each virus of Circoviridae.There is much comparability between PCV and its host in their synonymous codon usage, suggesting that the natural selection pressure from the host factor also affect the codon usage patterns of PCV. In particular, PCV genotype II is in synonymous codon usage more similar to pig than to PCV genotype I, which may be one of the most important molecular mechanisms of PCV genotype II to cause disease. The calculations results of the relative abundance of dinucleotides indicate that the composition of dinucleotides also plays a key role in the variation found in synonymous codon usage in PCV. Furthermore, geographic factors, the general average hydrophobicity and the aromaticity may be related to the formation of codon usage patterns of PCV.</p> <p>Conclusion</p> <p>The results of these studies suggest that synonymous codon usage pattern of PCV genome are the result of interaction between mutation pressure and natural selection from its host. The information from this study may not only have theoretical value in understanding the characteristics of synonymous codon usage in PCV genomes, but also have significant value for the molecular evolution of PCV.</p

Influencing factors to the friction charging in water delivery metal pipeline

AbstractElectrochemical reaction is the major influencing factor to the metal pipe corrosion, and the extra electric charge generated in the metal by the friction of the metal pipe with water flow will affect the electrochemical reaction and the corrosion process of the metal pipe. The effects of the kinds of water, the water flow rates and the installing of an electric charge trapper on the electric charge are investigated by measuring the current and voltage generated in the test pipe. The research results show that when using the deionized water as the test water, the current increases and the voltage decreases with the rising of the flow rate; the voltage generated in the case of using the city water has a different change from that of using the deionized water, it is smaller than that of using the deionized water with keeping it in static state, and then increases with the rising of the flow rate; however, with the increasing of the flow rate, the voltages generated in both cases of using deionized water and city water are close to a same value; the voltage generated in the case of installing the electric charge trapper is smaller than that of without the electric charge trapper. It is because that some electric charge in the water flow are caught by the electric charge trapper and then transported to the metal to neutralize an equal amounts of electric charge

New definition of potential spicity by the least square method

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 7351-7365, doi:10.1029/2018JC014306.A differentiable function whose contours are orthogonal to potential density (σ) contours does not exist. However, such a function, called potential spicity (π), can be defined in the least square sense; these two functions form a practically orthogonal coordinate system in potential temperature‐salinity (θ‐S) space. Thus, in addition to the classical potential temperature‐salinity (θ‐S) diagram, seawater properties can be studied in the potential density‐potential spicity (σ − π) diagram.Guangzhou Science and Technology Program key projects. Grant Number: 201804020056 National Natural Science Foundation of China. Grant Numbers: 41476167, 91752108 National Natural Science Foundation of Guangdong Province, China Grant Number: 2016A030311042; Strategic Priority Research Program of the Chinese Academy of Sciences Grant Number: XDA11030302; Guangzhou Science and Technology Program; NSF of Guangdong Province, China2019-04-1

Sign structure in the square-lattice tt-t′t^\prime-JJ model and numerical consequences

Understanding the doped Mott insulator is a central challenge in condensed matter physics. This study identifies an intrinsic Berry-phase-like sign structure for the square-lattice $t$-$t'$-$J$ model with the nearest-neighbor ($t$) and next-nearest-neighbor hopping ($t'$), which could help explain the origin of the quasi-long-range superconducting and stripe phases observed through density matrix renormalization group (DMRG) calculation. We first demonstrate that the hole binding underlies both the superconducting and stripe orders, and then show that the hole pairing generically disappears once the phase-string or mutual statistics component of the sign structure is switched off in DMRG calculation. In the latter case, the superexchange interaction no longer plays a crucial role in shaping the charge dynamics, where a Fermi-liquid-like phase with small hole Fermi pockets is found. It is in sharp contrast to the large Fermi surfaces in either the stripe phase found at $t'/t0$ in the original $t$-$t'$-$J$ model on the 6-leg ladder.Comment: 13 pages, 10 figure