Calculations of Chern number: equivalence of real-space and twisted-boundary-condition formulae

Chern number is a crucial invariant for characterizing topological feature of two-dimensional quantum systems. Real-space Chern number allows us to extract topological properties of systems without involving translational symmetry, and hence plays an important role in investigating topological systems with disorder or impurity. On the other hand, the twisted boundary condition (TBC) can also be used to define the Chern number in the absence of translational symmetry. Here we study the relation between these different definitions of Chern number. Through analyzing the TBC formula and two real-space formulae (the non-commutative Chern number and the Bott index formula), we show that these approaches are equivalent in the thermodynamic limit. The equivalence is also numerically confirmed via the Haldane model.Comment: 16 pages, 6 figure

Floquet Engineering of Hilbert Space Fragmentation in Stark Lattices

The concept of Hilbert space fragmentation (HSF) has recently been put forward as a routine to break quantum ergodicity. While HSF widely exists in dynamical constraint models, it is still challenging to tune HSF. Here, we propose a scheme to tune HSF in a one-dimensional tilted lattice of interacting spinless fermions with periodically driven tunneling. The dynamics is governed by effective Hamiltonians with kinetic constraints, which appear as density-dependent tunneling in the weak-tunneling perturbation expansion. The kinetic constraint can be tuned via changing the driving frequency, and three different kinds of strong HSF can be engineered. In general, the system is strongly constrained and exhibits a strong HSF. Two partial resonance frequencies are analytically given by a time-dependent perturbation theory for Floquet systems, at which some kinetic constraints are released and the system exhibits another two different strong HSF. We demonstrate the perturbation analysis with exact numerical simulation of the entanglement entropy, the density correlation functions and the saturated local density profiles. Our result provides a promising way to control HSF through Floquet engineering

Mechanical properties of La-based bulk amorphous alloy and composites

Influence of different microstructure of La-based fully amorphous samples and its composites on the impact fracture energy were investigated and discussed. Results showed improvement in fracture energy of glassy metals with the presence intermetallic phases, but deteriorated in the presence of dendrite phases and high volume % of crystalline phases.Singapore-MIT Alliance (SMA

Bacteria in the apical root canals of teeth with apical periodontitis

Background/PurposeBacteria in the tooth root canal may cause apical periodontitis. This study examined the bacterial species present in the apical root canal of teeth with apical periodontitis. Antibiotic sensitivity tests were performed to evaluate whether these identified bacterial species were susceptible to specific kinds of antibiotics.MethodsSelective media plating and biochemical tests were used first to detect the bacterial species in samples taken from the apical portion of root canals of 62 teeth with apical periodontitis. The isolated bacterial species were further confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry.ResultsWe found concomitant presence of two (32 teeth) or three species (18 teeth) of bacteria in 50 (80.6%) out of 62 tested teeth. However, only 34 bacterial species were identified. Of a total of 118 bacterial isolates (83 anaerobes and 35 aerobes), Prophyromonas endodontalis was detected in 10; Bacteroides, Dialister invisus or Fusobacterium nucleatum in 9; Treponema denticola or Enterococcus faecalis in 8; Peptostreptococcus or Olsenella uli in 6; and Veillonella in 5 teeth. The other 25 bacterial species were detected in fewer than five teeth. Approximately 80–95% of bacterial isolates of anaerobes were sensitive to ampicillin/sulbactam (Unasyn), amoxicillin/clavulanate (Augmentin), cefoxitin, and clindamycin. For E. faecalis, 85–90% of bacterial isolates were sensitive to gentamicin and linezolid.ConclusionRoot canal infections are usually caused by a mixture of two or three species of bacteria. Specific kinds of antibiotic can be selected to control these bacterial infections after antibiotic sensitivity testing

Which Should Be Used First for ALK-Positive Non-Small-Cell Lung Cancer: Chemotherapy or Targeted Therapy? A Meta-Analysis of Five Randomized Trials

Background and objectives: Targeted therapy is widely used in the era of precision medicine. Whether the sequence in which targeted therapy and chemotherapy are performed matters, is however not known. We examined the impact of the sequential treatment of targeted therapy and chemotherapy among advanced anaplastic lymphoma kinase (ALK), non-small cell lung cancer (NSCLC) patients. Materials and Methods: Randomized controlled trials comparing the use of ALK inhibitors with chemotherapy were included in this meta-analysis. We estimated the hazard ratios (HRs) and 95% confidence intervals (CI), for progression-free survival (PFS) and overall survival (OS) from a random effects model. Two-sided statistical tests were used to determine the significance of these estimates. Results: In five eligible studies (1404 patients), ALK targeted therapy, in comparison with chemotherapy, had a significantly higher PFS (HR = 0.48; 95% CI, 0.42(-)0.55), but not significantly higher OS (HR = 0.88; 95% CI, 0.72(-)1.07). Crossover from chemotherapy to ALK inhibitors was allowed after progression in all trials. The sensitivity analysis of the use of ALK inhibitors as either the first- or second-line treatment, showed improvements in PFS but not in OS. Conclusions: Our results indicate that using targeted therapy first improved PFS, but that the sequence in which the treatments were performed did not cause a significant difference in overall survival

Developing the Evaluation Framework of Technology Foresight Program: Lesson Learned from European Countries

Atlanta Conference on Science and Innovation Policy 2009This presentation was part of the session : Roundtables on Methods, Measures, and DataThis material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Foresight activities are valued in many countries since 1990s due to their long term strategic planning. These governments consequently allocate most resources in these foresight activities. As a result, the paper mainly develops the evaluation framework of technology foresight program, by integrating the concepts of evaluation and logic framework with the experience of foresight evaluation from developed countries, for instance European Union, Britain etc., to realize the outcomes of implementing foresight activities. Taking Sweden as a case study, the paper is also proposed to show the effectiveness of this new framework

Stable interaction-induced Anderson-like localization embedded in standing waves

We uncover the interaction-induced \emph{stable self-localization} of bosons in disorder-free superlattices. In these nonthermalized multi-particle states, one of the particles forms a superposition of multiple standing waves, so that it provides a quasirandom potential to localize the other particles. We derive effective Hamiltonians for self-localized states and find their energy level spacings obeying the Poisson statistics for Anderson-like localization. Surprisingly, we find that the correlated self-localization can be solely induced by interaction in the well-studied nonintegrable Bose-Hubbard models, which has been overlooked for a long time. We propose a dynamical scheme to detect self-localization, where long-time quantum walks of a single particle form a superposition of multiple standing waves for trapping the subsequently loaded particles. Our work provides an experimentally feasible way to realize stable Anderson-like localization in translation-invariant disorder-free systems

Identification of microRNA precursors in Bruguiera spp.

MicroRNAs (miRNA) are approximately 22 nt single stranded functional RNAs derived from long stem-loop precursors transcribed by RNA polymerase II. They regulate gene expression through post-transcriptional gene silencing and are important for the regulation of growth, development and stress responses in plants. Mature nucleotide sequences of many miRNA families are highly conserved across the plant kingdom and can be used to identify and annotate homologs and potential miRNA targets. In this study, mature miRNA sequences retrieved from the miRNA registry (miRBase) were used to identify precursor sequences of miRNA orthologs and their potential targets among Expressed Sequence Tags (ESTs) of the mangrove species Bruguiera cylindrica (L.) Blume, B. gymnorhiza (L.) Lam. and B. sexangula (Lour.) Poir. Candidate miRNA precursors, which potentially belong to the miR156/7, miR396 and miR529 families, had high sequence identity between Bruguiera cylindrica and Bruguiera gymnorhiza, and expression of RNA was confirmed in both species. A number of candidate targets for miR396 and miR529 were also identified among EST from B. gymnorhiza