RNAGCN: RNA tertiary structure assessment with a graph convolutional network

RNAs play crucial and versatile roles in cellular biochemical reactions. Since experimental approaches of determining their three-dimensional (3D) structures are costly and less efficient, it is greatly advantageous to develop computational methods to predict RNA 3D structures. For these methods, designing a model or scoring function for structure quality assessment is an essential step but this step poses challenges. In this study, we designed and trained a deep learning model to tackle this problem. The model was based on a graph convolutional network (GCN) and named RNAGCN. The model provided a natural way of representing RNA structures, avoided complex algorithms to preserve atomic rotational equivalence, and was capable of extracting features automatically out of structural patterns. Testing results on two datasets convincingly demonstrated that RNAGCN performs similarly to or better than four leading scoring functions. Our approach provides an alternative way of RNA tertiary structure assessment and may facilitate RNA structure predictions. RNAGCN can be downloaded from https://gitee.com/dcw-RNAGCN/rnagcn.     

Design studies on the 4π γ-ray calorimeter for the ETF experiment at HIRFL-CSR

A high detection efficiency calorimeter which is used to detect γ-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed. Design of the geometry, results of the crystal tests and Monte Carlo simulations are presented in this paper. The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry. And the calorimeter is competent for the future External Target Facility (ETF) experiments.     

反质子与离子研究装置FAIR 介绍

 未来几年, 在德国将会建成一个新的国际科学装置FAIR。FAIR 是一个综合性的粒子加速器系统, 它是反质子与离子研究装置(Facility for Antiproton and IonResearch)的简称。FAIR 建成后, 将能提供任意一种稳定或非稳定化学元素(从氢到铀)离子的高能量和高强度的束流, 且束流具有前所未有的高品质。FAIR 还将提供短寿命原子的次级束流和反质子束流。FAIR 涵盖了很广的与离子相关的科学目标, 建成后它将为全欧洲乃至全世界的科学家开展前沿研究提供优良条件。     

Performance of a double sided silicon strip detector as a transmission detector for heavy ions

The performance of a double sided silicon strip detector （DSSSD）, which is used for the position and energy detection of heavy ions, is reported. The analysis shows that although the incomplete charge collection （ICC） and charge sharing （CS） effects of the DSSSD give rise to a loss of energy resolution, the position information is recorded without ambiguity. Representations of ICC/CS events in the energy spectra are shown and their origins are confirmed by correlation analysis of the spectra from both the junction side and ohmic side of the DSSSD.     

同位旋激发能研究

在扩展的Skyrme有效相互作用下,利用Hartree-Fock理论研究了同位旋激发能与温度、密度的关系.结果表明同位旋激发能随密度的降低以及温度的增加而降低.同时研究了对称能与同位旋激发能的关系,指出对称能是同位旋激发能的一部分,且占相当大的比重.最后研究了不同的势参数下,同位旋激发能随相对中子过剩的变化关系,发现同位旋激发能较强地依赖于对称能强度系数,而对不可压缩系数以及有效质量不太敏感.从而为实验上通过研究同位旋激发能来提取核物质状态方程中的对称能部分指出了一条途径.     

用于中能重离子反应测量的塑料闪烁探测器阵列

描述了用于中能(10-100MeV/u)重离子核反应前角度(5°≤θ≤20°)测量的36单元phoswich闪烁探测器阵列.每个phoswich探测器单元由1mm厚的快塑料闪烁体NE102A和100mm厚的慢塑料闪烁体NE115组成,用传统的快、慢门控制的QDC积分方法,对Z=1-20范围的碎片得到了好的粒子鉴别,其粒子分辨能力Z/△Z～45.     

30MeV/u 40Ar引起的反应中核温度参数的提取

利用同位素产额比方法,提取了30MeV/u ⁴⁰Ar轰击⁵⁸Ni,⁶⁴Ni和¹¹⁵In的反应中中等质量碎片(IMFs:3≤Z≤8)的发射体的核温度参数,给出了“表观”温度与一些物理量的依赖关系以及对边馈(side-feeding)效应的影响进行修正后的温度参数. 并就此进行了简单的讨论.     

用于放射性束流的RFQ冷却聚束器

简要概述RFQ冷却聚束器的基本原理, 并给出了利用SIMION程序模拟的部分结果. 设计中的RFQ冷却聚束器与国际上其它同类设备相比, 具有特征半径大、入射粒子的允许能量上限值高和氦气气压高的特点, 因此本文最后对需要克服的困难作了一个简要的阐述.     

RIBLL终端LASCAR闪烁体阵列探测器研制进展

介绍了RIBLL终端LASCAR闪烁体阵列探测器的工作原理和结构特点. 描述了为满足放射性核束实验的要求而对阵列所作的重要改进. 给出了LASCAR构型优化改造的工作设想和实施步骤. The principles and structure characteristics of LASCAR scintillator array detector at RIBLL terminal are described. Special emphases are laid upon the latest progress for the development of LASCAR array detector to meet the requirements of the RIB experiments. The working plan and steps for optimizing configuration of the LASCAR multi unit neutron scintillator array detector are also presented.