The distribution of pelagic tars and plastics in the south Atlantic bight

Pelagic tars and plastics were sampled on six MARMAP cruises in the southeastern continental shelf and slope waters of the United States using a Boothbay neuston net. Both tars and plastic beads were widespread throughout the study area and the incidence of these contaminants increased offshore. Distribution patterns appeared to be related to currents. Average tar and plastic concentrations obtained on recent cruises were similar to concentrations noted in previous MARMAP sampling programmes along the northwestern Atlantic and Gulf coasts.     

Imagining the border and Southern spaces: Cinematic explorations of race and gender

For some time the US-Mexico border has been a symbol – and site – of conflict, collaboration, and transnational mobility. Related to the border, the topic of undocumented immigration, and Mexican migrants in particular, has received considerable attention in US mainstream media. Cinema in particular, provides a context for producing and interrogating discourses of nationalism, nativism, and fear. The cinematic examples I draw on illustrate an ongoing fear (and terror) about borders and border crossing of various forms. In this paper I explore how narratives of borders and nationhood are mapped onto immigrant bodies and border spaces through specific filmic representations. In order to undertake this study I focus on three cinematic examples exploring immigration at the US-Mexico border – Touch of Evil, The Border and Lone Star. I examine how concepts of borders, race, and gender, and tropes of ‘The South’ are reterritorialized around immigrant bodies and specific locales. I argue that an inability to control and ‘fix’ boundaries around possible ‘threats’ to specific US spaces and identities is counteracted by displacing this fear onto more easily marked targets that are viewed as posing challenges to US national (and personal) security, i.e., undocumented immigrants. At the same time, cinematic images illustrate that the threats and spaces for immigrants themselves become increasingly marginalized, blurred, and frequently erased. This revised version was published online in August 2006 with corrections to the Cover Date.     

剩余视极化率异常在寻找焦家式深部金矿床的应用研究

本文首次提出剩余视极化率异常的概念和求 取公式。利用已知焦家式深部金矿床上所 测得大、 小两种极距激电中梯视极化率ηα,而求得的剩余视 极化率ηαsy,经与已知深部矿床对比,发现其ηαsy异 常具有单纯反映矿体的能力,而与破碎带内的强蚀 变岩石所形成的极化率异常无关。     

Characterisation of glacial sediments using geophysical methods for groundwater source protection

A sequence of glacial and alluvial deposits overlying the Cretaceous Chalk in Eastern England was characterised using two geophysical techniques: electrical resistivity imaging and electromagnetic (EM) induction. Extensive geological data were available from trenching and boreholes. Synthetic modelling of the electrical resistivity imaging technique was undertaken to identify its limitations and to optimise survey design. The EM induction method provided a quick and cost-effective reconnaissance technique for identifying large-scale lateral variation in lithology, and for siting resistivity profiles and further boreholes. The resistivity imaging technique provided detailed information on the vertical continuity of permeable units, and was able to identify permeable pathways through the sequence. Certain limitations in detecting thin sand or gravel layers underlying electrically conductive clay were seen in both the synthetic and field data. Nevertheless, the study shows that knowledge of these limitations allows interpretation for the purpose of groundwater vulnerability assessment, given that an appropriate amount of invasive investigation has been conducted.     

地图模糊矩阵模型与制图术语表述数学化研究

笔者在过去所研究地图模糊矩阵模型的基础上,进一步探讨了建立地图模糊矩阵模型问题,通过矩阵运算来对地图学中有关制图综合、图象变换等概念给出了数学定义,从而使概念表述数学化。     

微机地图图形工作站上地图数字化子系统的设计与实现

借助于微型计算机而建立的地图图形工作站其目的在于完成数字化地图生产,即从地图数据的获取、管理、编辑、更新到图形输出等一系列过程。而地图数字化子系统则是该工作站上完成数据获取这一最初也是最重要过程的软件系统。文中介绍了笔者研制的地图图形工作站上的地图数字化子系统。该系统是在自行设计和研制的地图图形工作站的总框架下完成的,现已具备数字地图产业化生产能力,能有效地配合工作站完成数字地图的生产。同时,该系统对于不同的数据获取途径以及诸如我国地(形)图的独特要求(如汉字注记的处理)等方面有良好的适应性。     

一种消除stokes积分卷积化近似误差影响的有效方法

在应用快速Hartly变换(FHT)或快速Fourier变换(FFT)计算Stokes积分公式时,总是先将Stokes 公式化成卷积形式,然后用 FHT或 FFT完成卷积运算,从而避免了复杂费时的积分计算。但由于 Stokes公式不严格满足卷积定义,欲将其化成卷积形式必须作一些近似。这种近似虽能在一定精度范围满足要求,但对于高精度要求仍有不能允许的计算误差。本文建议采用球面坐标转换方法,能有效地消除无论是用 FHT或 FFT 计算Stokes 积分卷积化所带来的误差影响。     

测量球面无标记物体定轴转动角位移的客观散斑法

本文提出了测量球面无标记物体定轴转动角位移的客观散斑法。通过记录球面散射的散斑位移,计算球面物体的定轴角位移,并给出了实验验证。测量方法简单、测量精度高。实验结果与理论相符。