Novel Two-dimensional Carbon Allotrope with Strong Electronic Anisotropy

Two novel two-dimensional carbon allotropes comprised of octagons and pentagons are proposed based on the first-principles calculations. The two carbon allotropes, named OPG-L and OPG-Z, are found to have distinct properties. OPG-L is metallic, while OPG-Z is a gapless semimetal. Remarkably, OPG-Z exhibits pronounced electronic anisotropy with highly anisotropic Dirac points at the Fermi level. A tight-binding model is suggested to describe the low-energy quasiparticles, which clarifies the origin of the anisotropic Dirac points. Such an anisotropic electronic characteristic of OPG-Z is expected to have wide implications in nano-electronics.Comment: 6 pages, 5 figures (accepted by Physical Review B

Efficient Spatial Keyword Search in Trajectory Databases

An increasing amount of trajectory data is being annotated with text descriptions to better capture the semantics associated with locations. The fusion of spatial locations and text descriptions in trajectories engenders a new type of top-$k$ queries that take into account both aspects. Each trajectory in consideration consists of a sequence of geo-spatial locations associated with text descriptions. Given a user location $\lambda$ and a keyword set $\psi$, a top-$k$ query returns $k$ trajectories whose text descriptions cover the keywords $\psi$ and that have the shortest match distance. To the best of our knowledge, previous research on querying trajectory databases has focused on trajectory data without any text description, and no existing work has studied such kind of top-$k$ queries on trajectories. This paper proposes one novel method for efficiently computing top-$k$ trajectories. The method is developed based on a new hybrid index, cell-keyword conscious B$^+$-tree, denoted by \cellbtree, which enables us to exploit both text relevance and location proximity to facilitate efficient and effective query processing. The results of our extensive empirical studies with an implementation of the proposed algorithms on BerkeleyDB demonstrate that our proposed methods are capable of achieving excellent performance and good scalability.Comment: 12 page

Clinical observation of torsional phacoemulsification for a beginner

AIM: To observe the clinical security of torsional phacoemulsification for a beginner.<p>METHODS: The clinical data of 200 eyes who accepted torsional phacoemulsification by a beginner from February 2012 to March 2013 were reviewed. The operation complications were analyzed and the postoperative effect was assessed.<p>RESULTS: There was no collapse of the anterior chamber during operation. When the last nuclear was removed the surge occurred mildly. Posterior capsular rupture happened in 8 eyes, 5 eyes' intraocular lens#IOL#implanted in sclera sulcus after anterior vitrectomy, 3 eyes' IOL in bag without vitreous outflow. One eye without continuous curvilinear capsulotomy was transferred to the superior doctor for extracapsular cataract extraction#ECCE#. One eye with the loose zonular fiber was implanted a capsular tension ring by the superior doctor. Seven cases need suture because of short sclera tunnel incisions. Uncorrected visual acuity a week after operation: 2 eyes#1%#<0.05, 31 eyes#15.5%#0.05-<0.3, 64 eyes#32%#≥0.3, 103 eyes#51.5%#≥0.5. There was no grade 3 corneal edema. The high intraocular pressure can be controlled by anterior chamber penetration or drugs.<p>CONCLUSION: The technique of torsional phacoemulsification is safe and effective for a beginner

Transport properties of dense deuterium-tritium plasmas

Consistent descriptions of the equation of states, and information about transport coefficients of deuterium-tritium mixture are demonstrated through quantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm$^{3}$ and a temperature of $10^{4}$ eV). Diffusion coefficients and viscosity are compared with one component plasma model in different regimes from the strong coupled to the kinetic one. Electronic and radiative transport coefficients, which are compared with models currently used in hydrodynamic simulations of inertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is also discussed from the highly degenerate to the intermediate region.Comment: 4 pages, 3 figure