catena-Poly[[diaqua­cobalt(II)]-μ-4,4′-[1,4-phenyl­enebis(­oxy)]dibutano­ato-κ4 O,O′:O′′,O′′′]

In the title coordination polymer, [Co(C14H16O6)(H2O)2]n, the CoII ion, situated on a twofold rotation axis, is coordinated by four O atoms from two 4,4′-[1,4-phenyl­enebis(­oxy)]dibutano­ate (L) ligands and two water mol­ecules in a highly distorted octa­hedral geometry. Each L ligand is situated on an inversion center and bridges two CoII atoms, forming a zigzag polymeric chain propagating in [10]. Inter­molecular O—H⋯O hydrogen bonds further consolidate the crystal packing

Bipartite Flat-Graph Network for Nested Named Entity Recognition

In this paper, we propose a novel bipartite flat-graph network (BiFlaG) for nested named entity recognition (NER), which contains two subgraph modules: a flat NER module for outermost entities and a graph module for all the entities located in inner layers. Bidirectional LSTM (BiLSTM) and graph convolutional network (GCN) are adopted to jointly learn flat entities and their inner dependencies. Different from previous models, which only consider the unidirectional delivery of information from innermost layers to outer ones (or outside-to-inside), our model effectively captures the bidirectional interaction between them. We first use the entities recognized by the flat NER module to construct an entity graph, which is fed to the next graph module. The richer representation learned from graph module carries the dependencies of inner entities and can be exploited to improve outermost entity predictions. Experimental results on three standard nested NER datasets demonstrate that our BiFlaG outperforms previous state-of-the-art models.Comment: Accepted by ACL202

Do institutions matter? Estimating the effect of institutions on economic performance in China

This paper estimates the effect of institutions on economic performance using cross-city data from China. We argue that China's ongoing reforms are part of a long and circuitous historical transition from antiquity to modernity, which started about 150 years ago. Learning from Western countries has been a central aspect of this historical process. The West had a laThis paper estimates the effect of institutions on economic performance using cross-city data from China. We argue that China's ongoing reforms are part of a long and circuitous historical transition from antiquity to modernity, which started about 150 years ago. Learning from Western countries has been a central aspect of this historical process. The West had a large influence on the early stage of this transition, which has persisted to current reforms. This study uses the enrollment in Christian missionary lower primary schools in China in 1919 as an instrument for present institutions. Employing a two-stage least squares method, we find that the effect of institutions on economic performance in China is positive and significant. The results are robust according to various tests including additional controls, such as geographic factors and government policy-related variables.institutions; christian; geography; policy

Study of the anomalous cross-section lineshape of e^+e^-\to D\bar D at \psi(3770) with an effective field theory

We study the anomalous cross-section lineshape of $e^+e^-\rightarrow D\bar D$ with an effective field theory. Near the threshold, most of the $D\bar D$ pairs are from the decay of $\psi(3770)$. Taking into account the fact that the nonresonance background is dominated by the $\psi(2S)$ transition, the produced $D\bar D$ pair can undergo final-state interactions before the pair is detected. We propose an effective field theory for the low-energy $D\bar D$ interactions to describe these final-state interactions and find that the anomalous lineshape of the $D\bar D$ cross section observed by the BESII collaboration can be well described.Comment: 10 pages,6 figures, redo the calculation with PDS scheme and more discussions added, accepted by Phys.Lett.