3,978 research outputs found
Projective non-Abelian Statistics of Dislocation Defects in a Z_N Rotor Model
Non-Abelian statistics is a phenomenon of topologically protected non-Abelian
Berry phases as we exchange quasiparticle excitations. In this paper, we
construct a Z_N rotor model that realizes a self-dual Z_N Abelian gauge theory.
We find that lattice dislocation defects in the model produce topologically
protected degeneracy. Even though dislocations are not quasiparticle
excitations, they resemble non-Abelian anyons with quantum dimension sqrt(N).
Exchanging dislocations can produces topologically protected projective
non-Abelian Berry phases. The dislocations, as projective non-Abelian anyons
can be viewed as a generalization of the Majorana zero modes.Comment: 4 pages + refs, 4 figures. RevTeX
Synthetic Topological Degeneracy by Anyon Condensation
Topological degeneracy is the degeneracy of the ground states in a many-body
system in the large-system-size limit. Topological degeneracy cannot be lifted
by any local perturbation of the Hamiltonian. The topological degeneracies on
closed manifolds have been used to discover/define topological order in
many-body systems, which contain excitations with fractional statistics. In
this paper, we study a new type of topological degeneracy induced by condensing
anyons along a line in 2D topological ordered states. Such topological
degeneracy can be viewed as carried by each end of the line-defect, which is a
generalization of Majorana zero-modes. The topological degeneracy can be used
as a quantum memory. The ends of line-defects carry projective non-Abelian
statistics, and braiding them allow us to perform fault tolerant quantum
computations.Comment: 4 pages + references + 3 pages of supplementary material, 2 figures.
reference update
The Role of Impulsivity in Dietary Restraint and Counter-Regulation
Dietary restraint, or chronically controlling one\u27s weight through diet, is a difficult pursuit. When faced with tempting foods, only a minority of restrained eaters manage to regulate their intake. Impulsivity, a multidimensional construct implicated in addictive behaviors, may be a factor that predicts regulation. The goals of the current study were twofold: firstly, we examined the effect of consuming a diet-violating preload on state impulsivity, and secondly, we examined how dietary restraint and changes in state impulsivity interact to influence subsequent overeating. In a laboratory study, female participants (n=146) with differing levels of dietary restraint provided measures of their state impulsiveness before and after consuming a 16oz preload of either a milkshake (High Calorie group) or water (Control group). The two state impulsivity subtypes assessed were inhibitory control, measured using the Stop Signal Task (SST), and food-specific impulsive choice, measured using a modified Delay Discounting Task. Results showed that after consuming a preload, all participants showed decreases in food-specific impulsive choice but not in inhibitory control. For those in the milkshake condition who were high in dietary restraint, higher initial inhibitory control and larger decreases in food-specific impulsive choice predicted lower subsequent caloric intake. No effects of impulsivity on consumption were seen for participants in the Control condition. These results suggest that subtypes of state impulsivity play differential roles in the eating behaviors of restrained eaters, and highlight important predictors of counter-regulation. Understanding the causal pathway between restraint and counter-regulation informs future directions in creating healthy eating interventions
Doping a spin-orbit Mott Insulator: Topological Superconductivity from the Kitaev-Heisenberg Model and possible application to (Na2/Li2)IrO3
We study the effects of doping a Mott insulator on the honeycomb lattice
where spins interact via direction dependent Kitaev couplings J_K, and weak
antiferromagnetic Heisenberg couplings J. This model is known to have a spin
liquid ground state and may potentially be realized in correlated insulators
with strong spin orbit coupling. The effect of hole doping is studied within a
t-J-J_K model, treated using the SU(2) slave boson formulation, which correctly
captures the parent spin liquid. We find superconductor ground states with spin
triplet pairing that spontaneously break time reversal symmetry. Interestingly,
the pairing is qualitatively different at low and high dopings, and undergoes a
first order transition with doping. At high dopings, it is smoothly connected
to a paired state of electrons propagating with the underlying free particle
dispersion. However, at low dopings the dispersion is strongly influenced by
the magnetic exchange, and is entirely different from the free particle band
structure. Here the superconductivity is fully gapped and topological,
analogous to spin polarized electrons with px+ipy pairing. These results may be
relevant to honeycomb lattice iridates such as A2IrO3 (A=Li or Na) on doping.Comment: 8 pages + 6 pages supplementary material; 5 figures, 3 tabl
Periodic solutions for a delay model of plankton allelopathy on time scales
In this paper, a delay model of plankton allelopathy is investigated. By using the coincidence degree theory, sufficient conditions for existence of periodic solutions are obtained. The presented criteria improve and extend previous results in the literature
Acid-volatile sulfide and simultaneously extracted metals in surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea: Concentrations, spatial distributions and the indication of heavy metal pollution status
Surface sediments were collected from the coastal waters of southwestern Laizhou Bay and the rivers it connects with during summer and autumn 2012. The acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) were measured to assess the sediment quality. The results showed that not all sediments with [SEM]-[AVS] > 0 were capable of causing toxicity because the organic carbon is also an important metal-binding phase in sediments. Suppose the sediments had not been disturbed and the criteria of US Environmental Protection Agency had been followed, heavy metals in this area had no adverse biological effects in both seasons except for few riverine samples. The major ingredient of SEM was Zn, whereas the contribution of Cd - the most toxic metal studied - to SEM was 0 were capable of causing toxicity because the organic carbon is also an important metal-binding phase in sediments. Suppose the sediments had not been disturbed and the criteria of US Environmental Protection Agency had been followed, heavy metals in this area had no adverse biological effects in both seasons except for few riverine samples. The major ingredient of SEM was Zn, whereas the contribution of Cd - the most toxic metal studied - to SEM was <1%. The distributions of AVS and SEM in riverine sediments were more easily affected by anthropogenic activity compared with those in marine sediments. (C) 2013 Elsevier Ltd. All rights reserved
First-principles study, fabrication and characterization of (Zr0.25Nb0.25Ti0.25V0.25)C high-entropy ceramic
The formation possibility of a new (Zr0.25Nb0.25Ti0.25V0.25)C high-entropy
ceramic (ZHC-1) was first analyzed by the first-principles calculations and
thermodynamical analysis and then it was successfully fabricated by hot
pressing sintering technique. The first-principles calculation results showed
that the mixing enthalpy of ZHC-1 was 5.526 kJ/mol and the mixing entropy of
ZHC-1 was in the range of 0.693R-1.040R. The thermodynamical analysis results
showed that ZHC-1 was thermodynamically stable above 959 K owing to its
negative mixing Gibbs free energy. The experimental results showed that the
as-prepared ZHC-1 (95.1% relative density) possessed a single rock-salt crystal
structure, some interesting nanoplate-like structures and high compositional
uniformity from nanoscale to microscale. By taking advantage of these unique
features, compared with the initial metal carbides (ZrC, NbC, TiC and VC), it
showed a relatively low thermal conductivity of 15.3 + - 0.3 W/(m.K) at room
temperature, which was due to the presence of solid solution effects,
nanoplates and porosity. Meanwhile, it exhibited the relatively high
nanohardness of 30.3 + - 0.7 GPa and elastic modulus of 460.4 + - 19.2 GPa and
the higher fracture toughness of 4.7 + - 0.5 MPa.m1/2, which were attributed to
the solid solution strengthening mechanism and nanoplate pullout and microcrack
deflection toughening mechanism.Comment: 49 pages,6 figures, 4 table
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