几种理化因子对斑节对虾白斑杆状病毒(WSBV)感染力的影响

将部分纯化的ＷＳＢＶ暴露于不同理化条件下,通过人工感染的方法测定ＷＳＢＶ的感染力。结果表明,病毒在纯水中１ｈ能保持感染活性,全在３ｍｏｌ／Ｌ ＮａＣｌ的高盐溶液中１ｈ失去感染力;ＷＳＢＶ在３０℃中４ｈ感染活性丧失,在７０～９０℃中１０ｍｉｎ均失去感染力;当环境ｐＨ值为５以下或１２．６以上时,ＷＳＢＶ在１ｈ后丧失感染活性;ＮＰ０－４０,Ｔｒｉｔｏｎ－Ｘ－１００,ＣｌＯ２或甲醛等均能灭活ＷＳＢＶ。     

基于点云数据的地裂缝监测对象提取研究以江苏无锡光明村为例

利用三维激光扫描技术得到的无锡光明村点云数据建立模型,通过运用Geomagic软件对监测对象地裂缝进行特征识别,评价地裂缝以及其对周围建筑物的影响。运用统计原理及数值计算,通过选取特征点以及特征直线的方法,以得到地裂缝的倾向、走向、长度、深度及两侧高差等特征数值信息,并且得出创建的特征点个数与结果准确率之间的关系。其次,采用平面拟合的方法,利用拟合平面的特征法向量,通过几何变换与计算,对由地裂缝引起的周围建筑物（此处重点研究墙体）的变形变化进行计算,定性并定量地分析地裂缝对墙体的影响。通过对地裂缝的特征以及周围墙体受影响程度的分析,提供该地裂缝的整治建议,为该地区后续地质情况分析以及灾害后的修复工作提供指导。在此基础上提供一种利用Geomagic获取检测对象特征信息的方法。     

An upper limit to coronal X-rays from single,magnetic white dwarfs

Pointed ROSAT PSPC exposures of 9277 and 6992 sec, directed toward the nearby, single, cool, magnetic white dwarfs GR 290 and EG 250 yielded no counts significantly above the expected background rate. The corresponding flux limits (for an assumed source temperature of l keV) are 1.0 and 1.7 × 10⁻¹⁴erg cm⁻² s⁻¹, within the 0.1–2.5 keV bandpass of the instrument (99% confidence limits). This is more than an order of magnitude below the tentative detection level (for GR 290) and limits (for four other similar stars) obtained from archival Einstein data in 1991. The corresponding limits on coronal electron density are comparable with those implied if cyclotron emission is not responsible for any of the features observed in the optical spectra of magnetic white dwarfs. X-ray data currently provide no evidence for the existence of coronae around these stars. A final long observation (25,000 sec of GD 356) is scheduled for later this year on ROSAT, along with coordinated EUVE observations.     

Quantifying the spatial heterogeneity of points

Variation in the spatial heterogeneity of points reflects the evolutionary process or mechanism of geographical events. The key to depicting this variation is quantifying spatial heterogeneity. In this paper, the spatial heterogeneity of a point pattern is defined as the degree of aggregation-type deviation from complete spatial randomness. In such a case, a goodness-of-fit-type statistic based on the distribution of nearest-neighbor distances called the level of heterogeneity (LH*) is regarded as a standard measurement, and a normalized version called the normalized level of heterogeneity (NLH*) is proposed for datasets with different point numbers and study region areas. Considering the complex integration calculation of LH* and NLH*, simulation experiments are implemented to test the capability of some classic nearest-neighbor statistics in quantifying spatial heterogeneity. The results showed that except for the standard LH* statistic, only Clark and Evans’ statistic (A-w) and Byth and Ripley’s statistic (H-xw) are robust. Statistics NLH*, (A-w) and (H-xw) are validated by quantifying the spatial heterogeneity of two-dimensional crime events, three-dimensional earthquake events and four-dimensional origin-destination (OD) events. The results indicate that these statistics all have a reasonable explanation in quantifying spatial heterogeneity for real-world geographical events of different types and with different dimensions. Compared with NLH*, Clark and Evans’ (A-w) statistic and Byth and Ripley’s (H-xw) statistic are recommended from the perspective of accessibility.     

北京房山大理岩的岩石学微观特征及风化机理讨论

北京地区许多石质古建筑都使用了房山大石窝的大理岩来建造的。本文以汉白玉(白色大理岩)和青白石(青色大理岩)为例,通过薄片镜下观察、X射线衍射(XRD)、X射线荧光(XRF)、扫描电镜(SEM)和电子探针等测试手段,对房山大理岩的岩石学微观特征进行了研究。研究对象为取自房山大石窝的新鲜岩样和取自北京古代石质建筑的风化剥落物。结果证实北京大理岩主要矿物成分是白云石,部分大理岩还含有一定量的石英。基于图像处理软件,对汉白玉和青白石矿物晶体的粒径进行了统计分析。在此基础上,从温度变化、酸雨的溶解、水的溶蚀、微裂隙的盐类充填的角度分析了大理岩的风化机理。相关研究可为北京大理岩石质文物的修复保护提供科学参考。     

Point defects in crystalline zircon (zirconium silicate), ZrSiO<Subscript>4</Subscript>: electron paramagnetic resonance studies

This article outlines the present state of knowledge of paramagnetic defects in crystalline zircon as obtained mainly, but not exclusively, from electron paramagnetic resonance (EPR) studies in crystalline zircon (zirconium silicate, ZrSiO₄). The emphasis is on single-crystal studies where, in principle, unambiguous analysis is possible. Firstly, the crystallography of zircon is presented. Secondly, the relationships between available crystal-site symmetries and the symmetries of observed paramagnetic species in zircon, and how these observations lead to unambiguous assignments of point-group symmetries for particular paramagnetic species are detailed. Next, spin-Hamiltonian (SH) analysis is discussed with emphasis on the symmetry relationships that necessarily exist amongst the Laue classes of the crystal sites in zircon, the paramagnetic species occupying those sites and the SH itself. The final sections of the article then survey the results of EPR studies on zircon over the period 1960–2002.     

基于POI数据的山西省旅游景区分类及空间分布特征

运用大数据与传统地理信息系统相结合的方式,以山西旅游景区POI(Point of Interest)数据为研究对象,对其进行分类后,研究其总体空间分布格局、分布方向以及具体地市空间分布特征.结果 表明:山西旅游景区总体分布格局呈现晋中地区集聚特征,具体各类旅游景区的集聚形态与程度有所差异.其中,地文景观类旅游景区集聚于...     

Reply to discussion of Jamaican cenozoic ichnology: review and prospectus: (v. 50, p. 364–382)

Mitchell and Ramsook comment on the lithostratigraphic assignment of Jamaican Cenozoic ichnofossils discussed in Donovan et al. They argue that the Paleogene Richmond Formation should be subdivided to produce a ‘Moore Town formation’ in eastern Jamaica, but the latter remains undefined as a lithostratigraphic unit and no new lithostratigraphic evidence is produced to support their supposition. Further, their use of a flawed table of trace fossil distributions does not support their thesis. The distribution of trace fossils in the White Limestone Group presented by Donovan et al. follows the lithostratigraphic scheme that was current at the time that the research was originally undertaken in the early 2000s. Yet, whatever lithostratigraphic scheme is utilised for the island, it is apparent that the more accurate data is provided by the biostratigraphy of the larger benthic foraminifers. Copyright © 2015 John Wiley & Sons, Ltd.     

利用VB开发的MAPGIS明码数据格式文件生成系统

MAPGIS目前还没有提供直接由坐标数据输入成图的功能.利用VB开发的一个直接使用现成数据源生成MAPGIS的明码数据格式文件的系统,使得将现有数据加载到相关的地形、地质、物探等成果图件上的操作变得简单和十分方便.论述了系统的开发思路和主要特点.     

Accurate 3D comparison of complex topography with terrestrial laser scanner: Application to the Rangitikei canyon (N-Z)

Surveying techniques such as terrestrial laser scanner have recently been used to measure surface changes via 3D point cloud (PC) comparison. Two types of approaches have been pursued: 3D tracking of homologous parts of the surface to compute a displacement field, and distance calculation between two point clouds when homologous parts cannot be defined. This study deals with the second approach, typical of natural surfaces altered by erosion, sedimentation or vegetation between surveys. Current comparison methods are based on a closest point distance or require at least one of the PC to be meshed with severe limitations when surfaces present roughness elements at all scales. To solve these issues, we introduce a new algorithm performing a direct comparison of point clouds in 3D. The method has two steps: (1) surface normal estimation and orientation in 3D at a scale consistent with the local surface roughness; (2) measurement of the mean surface change along the normal direction with explicit calculation of a local confidence interval. Comparison with existing methods demonstrates the higher accuracy of our approach, as well as an easier workflow due to the absence of surface meshing or Digital Elevation Model (DEM) generation. Application of the method in a rapidly eroding, meandering bedrock river (Rangitikei River canyon) illustrates its ability to handle 3D differences in complex situations (flat and vertical surfaces on the same scene), to reduce uncertainty related to point cloud roughness by local averaging and to generate 3D maps of uncertainty levels. We also demonstrate that for high precision survey scanners, the total error budget on change detection is dominated by the point clouds registration error and the surface roughness. Combined with mm-range local georeferencing of the point clouds, levels of detection down to 6 mm (defined at 95% confidence) can be routinely attained in situ over ranges of 50 m. We provide evidence for the self-affine behaviour of different surfaces. We show how this impacts the calculation of normal vectors and demonstrate the scaling behaviour of the level of change detection. The algorithm has been implemented in a freely available open source software package. It operates in complex 3D cases and can also be used as a simpler and more robust alternative to DEM differencing for the 2D cases.