336 research outputs found
Critical behavior of Anderson transitions in higher dimensional Bogoliubov-de Gennes symmetry classes
Disorder is ubiquitous in solid-state systems, and its crucial influence on
transport properties was revealed by the discovery of Anderson localization.
Generally speaking, all bulk states will be exponentially localized in the
strong disorder limit, but whether an Anderson transition takes place depends
on the dimension and symmetries of the system. The scaling theory and symmetry
classes are at the heart of the study of the Anderson transition, and the
critical exponent characterizing the power-law divergence of localization
length is of particular interest. In contrast with the well-established lower
critical dimension of the Anderson transition, the upper critical
dimension , above which the disordered system can be described by
mean-field theory, remains uncertain, and precise numerical evaluations of the
critical exponent in higher dimensions are needed. In this study, we apply
Borel-Pad\'e resummation method to the known perturbative results of the
non-linear sigma model (NLM) to estimate the critical exponents of the
Boguliubov-de Gennes (BdG) classes. We also report numerical simulations of
class DIII in 3D, and classes C and CI in 4D, and compare the results of the
resummation method with these and previously published work. Our results may be
experimentally tested in realizations of quantum kicked rotor models in
atomic-optic systems, where the critical behavior of dynamical localization in
higher dimensions can be measured.Comment: 11 pages, 6 figure
Emergent self-duality in long range critical spin chain: from deconfined criticality to first order transition
Over the past few decades, tremendous efforts have been devoted to
understanding self-duality at the quantum critical point, which enlarges the
global symmetry and constrains the dynamics. In this letter, we employ
large-scale density matrix renormalization group simulations to investigate the
critical spin chain with long-range interaction .
Remarkably, we reveal that the long-range interaction drives the deconfined
criticality towards a first-order phase transition as decreases. More
strikingly, the emergent self-duality leads to an emergent symmetry and
manifests at these first-order critical points. This discovery is reminiscent
of self-duality protected multicritical points and provides the example of the
critical line with generalized symmetry. Our work has far-reaching implications
for ongoing experimental efforts in Rydberg atom quantum simulators.Comment: 5 + 10 pages, 9 figures. Any comments or suggestions are welcome
Identification and Discrimination of Salmonella enterica Serovar Gallinarum Biovars Pullorum and Gallinarum Based on a One-Step Multiplex PCR Assay
Salmonella enterica serovar Gallinarum biovars Pullorum (S. Pullorum) and Gallinarum (S. Gallinarum) can result in pullorum disease and fowl typhoid in avian species, respectively, and cause considerable economic losses in poultry in many developing countries. Conventional Salmonella serotyping is a time-consuming, labor-intensive and expensive process, and the two biovars cannot be distinguished using the traditional serological method. In this study, we developed a rapid and reliable one-step multiplex polymerase chain reaction (PCR) assay to simultaneously identify and discriminate the biovars Pullorum and Gallinarum. The multiplex PCR method focused on three specific genes, stn, I137_08605 and ratA. Based on bioinformatics analysis, we found that gene I137_08605 was present only in S. Pullorum and S. Gallinarum, and a region of difference in ratA was deleted only in S. Pullorum after comparison with that of S. Gallinarum and other Salmonella serovars. Three pairs of primers specific for the three genes were designed for the multiplex PCR system and their selectivity and sensitivity were determined. The multiplex PCR results showed that S. Pullorum and S. Gallinarum could be identified and discriminated accurately from all tested strains including 124 strains of various Salmonella serovars and 42 strains of different non-Salmonella pathogens. In addition, this multiplex PCR assay could detect a minimum genomic DNA concentration of 67.4 pg/μL, and 100 colony forming units. The efficiency of the multiplex PCR was evaluated by detecting natural-occurring Salmonella isolates from a chicken farm. The results demonstrated that the established multiplex PCR was able to identify S. Gallinarum and S. Pullorum individually, with results being consistent with traditional serotyping and biochemical testing. These results demonstrated that a highly accurate and simple biovar-specific multiplex PCR assay could be performed for the rapid identification and discrimination of Salmonella biovars Gallinarum and Pullorum, which will be useful, particularly under massive screening situations
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