Latent ancestral graph of structure vector autoregressive models

A class of latent ancestral graph for modelling the dependence structure of structural vector autoregressive (VAR) model affected by latent variables is proposed.The graphs are mixed graphs with possibly two kind of edges,namely directed and bidirected edges.The vertex set denotes random variables at difforent times.In Gaussian case,the latent ancestral graph leads to a simple parameterization model.A modified iterative conditional fitting algorithm is presented to obtain maximum likelihood estimation of the parameters.Furthermore,a log-likelihood criterion is used to select the most appropriate models.Simulations are performed using illustrative examples and results are provided to demonstrate the validity of the methods.     

东准噶尔盆地巴塔玛依内山组火山岩锆石U-Pb年代及Hf同位素研究

对准噶尔盆地陆梁隆起东部三参1井所钻巴塔玛依内山组玄武岩, 开展了详细锆石内部结构研究基础上的U-Pb年代学、微量元素和Hf同位素系统分析. 结果显示, 所有锆石都属岩浆成因, 都有一致的稀土配分型式, 都具明显的Ce正异常(δCe=5.06~134)、Eu负异常(δEu=0.06~0.55)和重稀土元素富集特征. 25颗锆石中, 谐和年龄主要分成3组, 分别是(300.4±1.3) Ma (n=11), (339.2±2.7) Ma (n=3)和(392.0±1.7) Ma (n=8); 此外, 还有3颗近谐和年龄锆石, 它们的²⁰⁶Pb/²³⁸U年龄分别是(510±7), (488±6)和(453±6) Ma. 最小的谐和年龄为(300.4±1.3) Ma, 可以代表巴塔玛依内山组火山岩的形成时代(如晚阶段年龄). 其他年龄如早泥盆世、奥陶纪等, 与盆地周缘岛弧火山岩(富集Pb)和蛇绿岩的时代一致, 而且这些年龄锆石都具有正的ε_Hf(t)值(+3.6~+10.5), 推测所研究火山岩穿越的盆地基底, 可能与由早古生代-中古生代的残余洋壳和岛弧地体组成有关. 晚石炭世锆石的ε_Hf(t)值变化于 +17.1~+4.2, 显示该玄武岩主要来源于软流圈地幔或亏损岩石圈地幔熔融作用, 熔体在上升-侵位过程中混染了少量较古老基底物质组分. 由于这些玄武岩是后碰撞幔源岩浆直接加入到地壳的物质表现, 推测东准噶尔地区晚石炭世已经有了大规模的陆壳垂向生长过程.     

Research on the technology of femtosecond laser micromachining based on image edge tracing

Aiming at fabrication of complex microstructures and micro-patterns, a kind of femtosecond laser micromachining technology based on the BMP image edge tracing was proposed. We introduced the general principle of this technology and discussed the implementation of the machining paths extraction, optimization, tracing and the feedback of the machining procession in detail. On the basis of this technology, control software for femtosecond laser micromachining was developed. Furthermore, we have accomplished the fabrication of complicated two-dimensional (2D) micro-patterns on a copper thin film. The results indicate that this technology can be used for digital control micromachining of complex patterns or microstructures at micron and submicron scales by femtosecond laser.     

Late Paleozoic magmatism in South China:Oceanic subduction or intracontinental orogeny?

A gneissic granite with an U-Pb age of 313±4 Ma was found in northeastern Fujian Province,South China.It is an S-type granite characterized by high K2O,Al2O3 and low SiO2,Na2O contents with high A/CNK ratio of 1.22 for the whole rock.Zircons with stubby morphology from the gneissic granite yield 206 Pb/238 U ages ranging from 326 to 301 Ma with a weighted average age of 313±4 Ma,and negative εHf(t) values from -8.35 to -1.74 with Hf model ages (TCDM) of 1.43 to 1.84 Ga.This S-type granite probably originated from late Paleoproterozoic crust in intracontinental orogeny.Integrated with previous results on paleogeographic reconstruction of South China,the nature of Paleozoic basins,Early Permian volcanism and U-Pb-Hf isotope of detrital zircons from the late Paleozoic to early Mesozoic sedimentary rocks,we suggest the occurrence of a late Paleozoic orogeny in the eastern Cathaysia Block,South China.This orogenic cycle includes Late Carboniferous (340-310 Ma) orogeny (compression) episode and Early Permian (287-270 Ma) post-orogenic or intraplate extension episode.Therefore,the late Paleozoic magmatism in the southeastern South China probably occurred during the intraplate orogeny rather than the arc-related process.     

Paleoproterozoic basement beneath the southern Jiangxi Province: Evidence from U-Pb ages and Lu-Hf isotopes in zircons from the Doushui lamprophyre

This paper presents geochemical analyses of a lamprophyre intruding the Caledonian Doushui granite body in Shangyou County, southern Jiangxi Province. U-Pb dating and Hf-isotope analyses are espe-cially carried out for zircons from it. Petrological and geochemical features show that the lamprophyre belongs to a high-K, weakly alkaline pyroxene-biotite lamprophyre. It is characterized by high Mg# (0.74), Ni (253 μg/g) and Cr (893 μg/g) contents, and also enriched in incompatible elements, such as REE, Rb, Sr...     

Cloning and functional analysis of the sequences flanking mini-Tn5 in the magnetosome-deleted mutant NM21 of Magnetospirillum gryphiswaldense MSR-1

A magnetosome-deleted mutant NM21 of Magnetospirillum gryphiswaldense MSR-1 was generated by mini-Tn5 lacZ2 transposon mutagenesis, and a 3073-bp fragment flanking mini-Tn5 lacZ2 in NM21 was cloned by Anchored PCR. Sequencing analysis showed that this fragment involved three putative ORFs; the mini-Tn5 lacZ2 was inserted into ORF1. Functional complementary test indicated that the 3073-bp fragment was required for biosynthesis of magnetosomes in M. gryphiswaldense MSR-1. The majority of proteins, which had h...     

体育教学改革的思考

一、存在的问题 （一）体育教学实践中思想不够开放。随着时代的发展,体育教学思想不断在寻求新的变化,体育教学大纲做了重大调整,从过去的以竞技体育教学为主要目的的教学逐步演变到以健康教育为主要的目的的体育教学,突出了以健康教育为主的体育教学,淡化了竞技体育教学。但在具体的体育教学实践过程中,由于传统的体育教学思想观念和体育教学体制难以在短时间内转变,体育教学仍然难以突破“重竞技,     

MR影像体素形态学的阿尔茨海默病自动分类方法

为了确定轻度认知功能障碍(MCI)与阿尔茨海默病(AD)患者发生萎缩的重要脑区,实现正常老年人(NC)对照组、MCI与AD三组人群的分类,选择了178名被试的脑部MR影像,利用体素形态学与方差分析方法,考察NC,MCI与AD三组人群的MR影像中灰质体积差异;然后,采用递归特征消去法对特征进行降维;最后,利用线性支持向量机对这3种人群进行分类.实验结果表明,MCI组与NC组、MCI组与AD组、AD组与NC组的平均分类准确率分别为(90.2±1.3)%,(74.7±0.9)%,100%.对分类产生重要影响的脑区包括海马、海马旁回、杏仁核、梭状回和嗅皮层等.所提方法不仅能有效揭示NC,MCI,AD三组人群的脑灰质差异,阐明MCI患者与AD患者脑区发生萎缩的过程与特性,而且能准确区分这3组人群,具有显著的临床应用价值.     

Towards a Wireless Sensor Platform for Energy Efficient Building Operation

Currently, the IT-support for energy performance rating of buildings is insufficient. So-called IT-platforms often "built" of an ad-hoc, inconsistent combination of off-the-shelf building management compo-nents, distributed data metering equipment and several monitoring software tools. A promising approach to achieve consistent, holistic performance data management is the implementation of an integrated, modular wireless sensor platform. This paper presents an approach of how wireless sensors can be seamlessly integrated into existing and future intelligent building management systems supporting improved building performance and diagnostics with an emphasis on energy management.     

Waveform diversity based sonar system for target localization

A new monostatic army system taking advantage of diverse waveforms to improve the performance of underwater target localization is proposed.Unlike the coherent signals between different elements in common active array,the transmitted signals from different elements here are spatially orthogonal waveforms which allow for array processing in the transit mode and result in an extension of array aperture.The mathematical derivation of Capon estimator for this sonar system is described in detail.And the performance of this orthogonal-waveform based sonar is analyzed and compared with that of its phased-array counterpart by water tank experiments.Experimental results show that this sonar system could achieve 12 dB-15 dB additional array gain over its phased-array counterpart,which means a doubling of maximum detection range.Moreover,the angular resolution is significantly improved at lower SNR.