Critical Exponents of the Classical 3D Heisenberg Model: A Single-Cluster Monte Carlo Study

We have simulated the three-dimensional Heisenberg model on simple cubic lattices, using the single-cluster Monte Carlo update algorithm. The expected pronounced reduction of critical slowing down at the phase transition is verified. This allows simulations on significantly larger lattices than in previous studies and consequently a better control over systematic errors. In one set of simulations we employ the usual finite-size scaling methods to compute the critical exponents $\nu,\alpha,\beta,\gamma, \eta$ from a few measurements in the vicinity of the critical point, making extensive use of histogram reweighting and optimization techniques. In another set of simulations we report measurements of improved estimators for the spatial correlation length and the susceptibility in the high-temperature phase, obtained on lattices with up to $100^3$ spins. This enables us to compute independent estimates of $\nu$ and $\gamma$ from power-law fits of their critical divergencies.Comment: 33 pages, 12 figures (not included, available on request). Preprint FUB-HEP 19/92, HLRZ 77/92, September 199

Topologically Protected Quantum State Transfer in a Chiral Spin Liquid

Topology plays a central role in ensuring the robustness of a wide variety of physical phenomena. Notable examples range from the robust current carrying edge states associated with the quantum Hall and the quantum spin Hall effects to proposals involving topologically protected quantum memory and quantum logic operations. Here, we propose and analyze a topologically protected channel for the transfer of quantum states between remote quantum nodes. In our approach, state transfer is mediated by the edge mode of a chiral spin liquid. We demonstrate that the proposed method is intrinsically robust to realistic imperfections associated with disorder and decoherence. Possible experimental implementations and applications to the detection and characterization of spin liquid phases are discussed.Comment: 14 pages, 7 figure

The influence of the accessory genome on bacterial pathogen evolution

Bacterial pathogens exhibit significant variation in their genomic content of virulence factors. This reflects the abundance of strategies pathogens evolved to infect host organisms by suppressing host immunity. Molecular arms-races have been a strong driving force for the evolution of pathogenicity, with pathogens often encoding overlapping or redundant functions, such as type III protein secretion effectors and hosts encoding ever more sophisticated immune systems. The pathogens’ frequent exposure to other microbes, either in their host or in the environment, provides opportunities for the acquisition or interchange of mobile genetic elements. These DNA elements accessorise the core genome and can play major roles in shaping genome structure and altering the complement of virulence factors. Here, we review the different mobile genetic elements focusing on the more recent discoveries and highlighting their role in shaping bacterial pathogen evolution

Evaluation of phosphorus in forest soils: Comparison of phosphorus uptake, extraction method and soil properties

Phosphorus in soils from plantation of red pine ( Pinus resinosa Ait.) was determined using six extractants: 0.002 N H 2 SO 4 (pH 3.0); 0.025 N HCl+ +0.03 N NH 4 F; 0.5 N NaHCO 3 (pH 8.5); N NH 4 OAc (pH 4.8); anion exchange resin (Dower −2, Cl-form); H 2 O. Correlations of extractable P with Al- and Al-+Fe-P indicated that these fractions are the dominant forms of inorganic P in most of the soils.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43473/1/11104_2005_Article_BF02149737.pd

Detection of progressive retinal nerve fiber layer thickness loss with optical coherence tomography using 4 criteria for functional progression

To compare the rates of retinal nerve fiber layer (RNFL) thickness loss using optical coherence tomography (OCT) in progressing versus nonprogressing eyes using 4 methods to define functional progression. Normal and glaucomatous eyes with ≥3 years of follow up were prospectively enrolled. Standard automated perimetry (Swedish Interactive Threshold Algorithm Standard 24-2) and OCT (Stratus OCT, Carl Zeiss Meditec, Dublin, CA) imaging were performed every 6 months in glaucomatous eyes. OCT imaging was performed annually in normal eyes. Functional progression was determined using early manifest glaucoma trial criterion, visual field index (VFI), Progressor software, and the 3-omitting method. Seventy-six eyes (46 glaucoma and 30 normal) of 38 patients were enrolled with a mean follow-up of 43.9 ± 5.02 months (range: 36 to 48 mo). Eleven eyes progressed using Progressor criterion, 5 eyes using VFI, 2 eyes using the 3-omitting method, and 2 eyes using Early Manifest Glaucoma Trial criterion. The annual rate of average RNFL loss (μm/y) was significantly greater (P0.05) in nonprogressing glaucomatous eyes compared with normal eyes. Using linear mixed-effect models, mean (P<0.001) and peak (P=0.01) intraocular pressure were significantly associated with rate of average RNFL atrophy in glaucomatous eyes. Despite differences in criteria used to judge functional progression, eyes with standard automated perimetry progression have significantly greater rates of RNFL loss measured using OCT compared with nonprogressing eyes