A modified TreePM code

We discuss the performance characteristics of using the modification of the tree code suggested by Barnes in the context of the TreePM code. The optimization involves identifying groups of particles and using only one tree walk to compute the force for all the particles in the group. This modification has been in use in our implementation of the TreePM code for some time, and has also been used by others in codes that make use of tree structures. We present the first detailed study of the performance characteristics of this optimization. We show that the modification, if tuned properly, can speed up the TreePM code by a significant amount. We also combine this modification with the use of individual time steps and indicate how to combine these two schemes in an optimal fashion. We find that the combination is at least a factor of two faster than the modified TreePM without individual time steps. Overall performance is often faster by a larger factor because the scheme for the groups optimizes the use of cache for large simulations.     

关于若干星座译名修改的建议

天上的星座及其名称可以说是一种独特的文化现象。由于恒星位置的相对固定,它们本身在天空就构成了一套潜在的符号系统,星座则是通过我们的划分和命名将其具体化了。中国古代的三垣二十八宿传统星官体系共有283星官,在晋朝就定型,一直沿用到清代封建王朝覆亡,而西方和现代使用的则是以古希腊托勒密时代星座为主体并在历史演变中逐渐形成的88星座体系。     

政策法规司：开门立法，全力做好“两法”修改

政策法规司司长王守智表示,今年将全力做好“两法”修改。积极配合国务院法制办,紧紧把握征地制度改革这一重大问题,解决低丘缓坡开发利用、集体建设用地流转、建设用地审批制度改革等紧迫问题,做好重大问题研究、数据测算和实地调研工作,推动尽快修订出台。将进一步梳理研究《矿产资源法》调整范围、矿业权与行政管理权的关系、资源利益调整、管理体制等重大问题．加强开门立法。     

对初中地理课本的几点修改建议

7月1日，香港回归祖国。当天下午，中央电视台直播香港特别区成立庆祝大会的实况，其间播映全国各省、市、自治区赠送的礼品时，映出全国地图作为背景，一一标示各省、市、自治区的轮廓形状。其中内蒙古自治区及其邻近省、区的轮廓璀状，和目前的地图上画法明显不同。     

对《中国地层指南》的几点修改意见和建议

本文根据《中国地层指南》试行10年来的实际情况,对《指南》提出了四点修改意见。文章具体分析了《指南》在生产科研中的指导意义和存在问题,对“地层的概念”、“地层划分的多重性”,“生物带”和“地层单位的符号”等四个方面提出了具体的修改意见。     

江苏省人民检察院办案技术楼试桩方案设计

通过单桩承载力估算及分析,将原试桩方案进行了修改,经过对试桩进行自平衡检测,证实改良方案满足设计荷载要求,从而为新的工程桩参数设计提供了理论依据,降低了工程成本,缩短了施工工期.     

《中图法》（第四版）地理学分散立类原因探析

本文论述了《中国图书馆分类法》(第四版以下简称《中图法》)地理类目的分布情况，探讨了地理学分散立类的原因，最后提出了具体的修改建议。     

Tectonic Stress Wave,Microfracture Wave,and a Modified Elastic-Rebound Model of Earthquakes

Based on a sample of some real earthquakes,we have suggested in previous papers that there is a density-tectonic stress wave with ultra-low frequency which is emitted from the epicenter region for months before earthquakes,and a micro-fracture wave 1 ～ 10 days before earthquakes. The former has been observed by different kinds of measurements and the latter has been observed by a few chance observations which consists of electromagnetic,gravitational and sonic fluctuations. We show real observational results that depict the two waves and they have very different frequencies,which are not difficult to discriminate. The classical elastic-rebound model is one of the most influential theories on earthquakes,and the thermodynamic elastic-rebound model has amended the classical framework. Considering the two waves above,we attempt to further modify the elasticrebound model,and the new framework could be called the "micro-fracture elasticrebound model". We infer that tectonic earthquakes could have three special phases: the accumulation of tectonic stress,micro-fracture,and main-fracture. Accordingly,there would be three waves which come from the epicenter of a tectonic earthquake,i. e. ,the tectonic stress wave with ultra-low frequency a few months before the earthquake,the micro-fracture wave about 1 ～ 10 days before the earthquake and the main-fracture wave (common earthquake wave).     

即时新闻

1中共中央、国务院近日印发了《关于加快推进农业科技创新持续增强农产品供给保障能力的若干意见》。涉及到关于土地问题的有如下意见:稳定和完善农村土地政策。加快修改完善相关法律,落实现有土地承包关系保持稳定并长久不变的政策。按照依法自愿有偿原则,引导土地承包经营权流转,发展多种形式的适度规模经营,