A Two-Phase Paradigm for Joint Entity-Relation Extraction

An exhaustive study has been conducted to investigate span-based models for the joint entity and relation extraction task.However,these models sample a large number of negative entities and negative relations during the model training,which are essential but result in grossly imbalanced data distributions and in turn cause suboptimal model performance.In order to address the above issues,we propose a two-phase paradigm for the span-based joint entity and relation extraction,which involves classifying the entities and relations in the first phase,and predicting the types of these entities and relations in the second phase.The two-phase paradigm enables our model to significantly reduce the data distribution gap,including the gap between negative entities and other entities,aswell as the gap between negative relations and other relations.In addition,we make the first attempt at combining entity type and entity distance as global features,which has proven effective,especially for the relation extraction.Experimental results on several datasets demonstrate that the span-based joint extraction model augmented with the two-phase paradigm and the global features consistently outperforms previous state-ofthe-art span-based models for the joint extraction task,establishing a new standard benchmark.Qualitative and quantitative analyses further validate the effectiveness the proposed paradigm and the global features.

Discovery of Three Variable Stars in Direction toward NGC 4565

We present the results of a variable star search in a field next to the edge-on galaxies NGC 4565 from the archive data of Beijing-Arizona-Taibei-Connecticut Multicolor Sky Survey. Three new variable stars were discovered. Based on spectra obtained from the 2.16m NAOC telescope, we identify two of these as RR Lyr stars and one as a special T Tauri star.

Preliminary Study on Pyrolysis of Polymethylsilsesquioxane by FT-IR and XPS

Changes of composition and structure of various samples of polymethylsilsesquioxane (PMSQ) pyrolysed at different temperature under flowing nitrogen were investigated by means of FT-IR and X-ray photoelectron spectroscopy. Two temperature domains correspond to important changes in the chemical composition of PMSQ. The former (Tp < 500oC) is related to the transition from regular structure to irregular structure and the latter (Tp > 500oC) is associated with the organic-inorgnic transition.

Detailed study of B037 based on HST images

B037 is of interest because it is both the most luminous and the most highly reddened cluster known in M31. Deep observations and high spatial resolution images with the Advanced Camera for Surveys on the Hubble Space Telescope （HST） first showed that this cluster is crossed by a dust lane. Photometric data in the F606W and F814W filters obtained in this paper indicate that colors of （F606W - F814W） in the dust lane are redder-0.4 mag than ones in the other regions of B037. The HST images show that this dust lane seems to be contained in B037, instead of in the M31 disk or the Milky Way. As far as we know, the formation of dust requires gas with a rather high metallicity. However, B037 has a low metallicity of [Fe/H] =→1.07 ±0.20. So, it seems improbable that the observed dust lane is physically associated with B037. It is clear that the origin of this dust lane is worthy of future study. In addition, based on these images, we present the precise variation of ellipticity and position angle, and of surface brightness profile, and determine the structural parameters of B037 by fitting a single-mass isotropic King model. In the F606W filter, we derive the best-fitting scale radius r0 = 0.56±0.02＂ （= 2.16±0.08 pc）, a tidal radius rt = 8.6±0.4I＂ （= 33.1±1.5 pc）, and a concentration index c = log（rt/ro） = 1.19±0.02. In the F814W filter, we derive r0 = 0.56 4± 0.01H （_=2.16 ±0.04 pc）, rt = 8.9 ±0.3＂ （= 34.3±1.2 pc）, and c = log（rt/ro） = 1.20±0.01. The extinction-corrected central surface brightness is μ0 = 13.53±0.03 mag arcsec^-2 in the F606W filter, and 12.85±0.03 mag arcsec^-2 in the F814W filter. We also calculate the half-light radius at rh = 1.05±0.03＂（= 4.04±0.12 pc） in the F606W filter and rh =1.07±0.01＂（= 4.12±0.04 pc） in the F814W filter. In addition, we derived the complete magnitudes of B037 in the V and I bands by transforming the magnitudes from the ACS system to the standard system, which are in good agreement with previous ground-based broad- band photometry studies.