Direct Observation of Valley-polarized Topological Edge States in Designer Surface Plasmon Crystals

The extensive research of two-dimensional layered materials has revealed that valleys, as energy extrema in momentum space, could offer a new degree of freedom for carrying information. Based on this concept, researchers have predicted valley-Hall topological insulators which could support valley-polarized edge states at non-trivial domain walls. Recently, several kinds of photonic or sonic crystals have been proposed as classical counterparts of valley-Hall topological insulators. However, direct experimental observation of valley-polarized edge states in photonic crystals is still difficult until now. Here, we demonstrate a designer surface plasmon crystal comprising metallic patterns deposited on a dielectric substrate, which can become a valley-Hall photonic topological insulator by exploiting the mirror-symmetry-breaking mechanism. Topological edge states with valley-dependent transport are directly visualized in the microwave regime. The observed edge states are confirmed to be fully valley-polarized through spatial Fourier transforms. Topological protection of the edge states at sharp corners is also experimentally demonstrated

Ontology-based Prediction of Compound Relations : A Study Based on SUMO

This paper explores the interaction between conceptual structure and morpho-syntax. In particular, we show that ontology-based conceptual classification can be used to predict internal relations in compounds. We propose an ontology-based approach to predict the semantic relation between the two component words in Mandarin VV compounds. A Mandarin VV compound is classified according to the eventive relation between the two simplex verbs. These relations specify how the eventive meanings of the two simplex verbs combine to form the meaning of the compound. The three types of eventive relations that we deal with in this paper are: coordinate, modificational, and resultative. Since the way in which two events combine with each other depends upon their event types, we hypothesize that the eventive relations can be predicted by the conceptual classified event types of the two simplex verbs. An approach of ontology-based prediction is proposed based on this hypothesis. The assignment of ontology classification for each simplex verb is based on SUMO and Sinica BOW. The correlation between the ontology class of each verb position and each eventive type is trained and scored based on a manually tagged lexical database. We encode the ontology information of each VV compound in a 3-tuple based on these correlation scores. This 3-tuple is represented as a three-dimensional vector and used to predict the eventive type of new VV compounds. Our classification experiment on unknown VV compounds yields good recall and precision

A Novel Method of Encoded Multiplexing Readout for Micro-pattern Gas Detectors

The requirement of a large number of electronic channels poses a big challenge for Micro-pattern Gas Detector (MPGD) to achieve good spatial resolution. By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5*5 cm2 Thick Gas Electron Multiplier (THGEM) detector using a 8 keV Cu X-ray source with 100um slit, where 166 strips are read out by 21 encoded readout channels. The test results show a good linearity in its position response, and the spatial resolution root-mean-square (RMS) of the test system is about 260 {\mu}m. This method has an attractive potential to build large area detectors and can be easily adapted to other detectors like MPGDs

The Necessary and Sufficient Conditions of Separability for Multipartite Pure States

In this paper we present the necessary and sufficient conditions of separability for multipartite pure states. These conditions are very simple, and they don't require Schmidt decomposition or tracing out operations. We also give a necessary condition for a local unitary equivalence class for a bipartite system in terms of the determinant of the matrix of amplitudes and explore a variance as a measure of entanglement for multipartite pure states.Comment: Submitted to PRL in Sep. 2004, the paper No is LV9637. Submitted to SIAM on computing, in Jan., 2005, the paper No. is SICOMP 44687. Under reviewing no

Amide Activation by Tf2O: Reduction of Amides to Amines by NaBH4 under Mild Conditions

An expeditious and practical method for the reduction of amides to amines is reported. The method is consisted of activation of amides with Tf2O followed by reduction with sodium borohydride in THF at room temperature. Various amides/lactams gave the corresponding amines in good to excellent yields, even with hindered amides and secondary amides. This method also presents other advantages such as TBDPS-group tolerance, short reaction time, simple workup and purification procedure.NSF of China [20832005]; National Basic Research Program (973 Program) of China [2010CB833200