θ扫描在粘土X射线定量分析中的应用

根据Ｘ射线衍射中θ扫描的基本原理，在理论分析的基础上认为θ曲线峰的形状能较精确地反映粘土矿物的定向水平和分层现象，而峰的积分面积比常规２θ曲线峰的积分面积更能客观地反映粘土矿物的含量。提出在粘土矿物Ｘ射线定量计算中用θ峰积分面积代替常规的２θ峰积分面积，并通过分析各粘土矿物的θ峰形了解样品中粘土矿物的分层情况     

Migmatite structures in the Central Gneiss Complex, Boca de Quadra, Alaska

Abstract Migmatite structures in the Coast Plutonic-Metamorphic Complex are well exposed in the inlet of Boca de Quadra, southeast Alaska. Two types of anatectic migmatites are present. Patch migmatites formed by in situ melting and subsequent crystallization of melt. Diktyonitic migmatites comprise a discontinuous veined network of leucocratic material, in which leucosomes enclose boudins of host rock. The margins of these boudins show the development of both melanosomes and shear band fabrics.
Strain analysis of diktyonitic melanosomes indicates that these regions have undergone volume decreases of 20-27%. This volume decrease is attributed to melt extraction into the adjacent fracture-filling leucosomes. Thus, diktyonitic migmatites formed by shear-induced segregation of partial melt, whereas in patch migmatites the lack of shear stresses inhibited melt segregation. The variable structural style of anatectic migmatites in Boca de Quadra is not related to host-rock composition, but may be due to differences in the amount of differential stress during migmatization. These in turn may be controlled by host-rock strength and/or diachroneity of migmatization and deformation.
Determination of volume changes during migmatization using strain analysis is potentially capable of discriminating intrusive and anatectic migmatites and consequently of documenting melt segregation and subsequent migration across crustal levels.     

1980年代以来英美城市社会极化问题及其研究

城市社会极化，是一种复杂的社会经济现象，是举世瞩目的现代社会问题。社会学家和地理学家从经济转变、种族、职业收入、财富分配、家庭结构和教育等多个角度对此进行了大量研究。本文着重介绍1980年代以来英美学者对社会极化问题的解释与论证，主要包括对城市社会极化的认识、新城市贫困(尤其是大城市中心区)的成因、种族隔离对少数民族(特别是黑人)的影响等方面。     

马氏珠母贝黄壳色家系的生长、壳色分离及总抗氧化能力比较

以马氏珠母贝(Pinctada fucata martensii)黄壳色作为选育指标构建了黄壳家系,对其4个生长性状和黄壳色性状分离比进行了统计分析,并测定了黄壳家系中黄壳、褐壳色个体不同组织中的总抗氧化能力(TAC)。结果发现:黄壳色性状能遗传并发生分离,其分离不完全符合孟德尔遗传分离定律;褐壳色亲本不会产生黄壳色子代,推测褐壳色是纯合子;第一代黄壳家系5、7月龄贝仅壳宽值显著小于褐壳家系(P0.05),壳高、壳长、总质量差异不显著, 11月龄贝仅壳长和壳宽值显著小于褐壳家系, 14、20月龄贝的壳高、壳长、壳宽、总质量这4个生长性状均极显著小于褐壳家系(P0.01);在第一代6个黄壳家系内,黄壳、褐壳色个体的4个生长性状差异不显著;黄壳色贝在足、心、性腺中的TAC显著低于褐壳色贝(P0.05);在鳃、闭壳肌、消化腺组织中TAC高于褐壳色贝,但差异不显著。     

基于共享度的上海郊区社区居民活动空间隔离及其影响因素

在流动性不断增强与居民活动模式日益多样化的背景下,城市社会空间分异与隔离的内涵不断扩展,居民在日常生活中面临的空间隔离受到关注。以活动空间为基础的社会空间分异研究快速兴起,以期从更加动态的视角理解城市社会空间。基于上海市郊区问卷调查数据,构建活动空间共享度指标,建立个体尺度的活动空间分异指数和孤立指数,刻画社区内不同收入群体的活动空间隔离状况,并建立活动空间共享度的多层模型分析活动空间隔离的影响因素。研究发现居住在同一社区的不同收入居民之间存在活动空间隔离,居民更愿意与其社会经济属性相似的人共享活动空间。活动空间隔离程度受到个体社会经济属性、社区设施状况、社区周边环境、社区人口密度和社会混合程度等因素的影响,居住在人口密度高、社会混合度高、社区商业配置良好、公共空间充足的开放社区能提高居民的活动空间共享度,增加不同群体社会接触的可能性。     

"全球城市"极化与上海社会空间分异研究

采用2000年全国第五次人口普查的统计数据,对上海社会空间分异的当前趋势进行探讨,结合中国崛起的历史性、地域性,针对上海城市经济结构、产业结构的转型问题,对全球化下我国城市社会空间发展的趋向进行分析,发现上海目前的社会经济结构尚未出现社会空间极化.通过对社会空间因子空间分布的实证分析,进一步揭示上海社会空间分异程度尚不明显.     

The grain-size characterisation of coastal sand from the Somme estuary to Belgium: Sediment sorting processes and mixing in a tide- and storm-dominated setting

Sand-rich Holocene to modern clastic deposits in the eastern English Channel and the southern North Sea coasts of France and Belgium occur extensively as nearshore-sand bank, estuarine-tidal flat, aeolian dune and beach sub-environments. Sand samples (n = 665) collected from these deposits suggest the presence of three different populations: a largely dominant (83%) medium to fine quartz sand population (“b”), and finer- (14%) and coarser-grained (4%) populations (respectively “c” and “a”). The distribution of these populations among the four sub-environments reflects tide- and storm-dominated sorting and transport processes and a variable degree of mixing. These populations are derived from a mixture of very fine- to very coarse-grained fluvial, outwash and paraglacial sediments deposited on the beds of the eastern English Channel and southern North Sea during the late Pleistocene lowstand. The nearshore-sand bank environment, which also corresponds to the main offshore source area of the coastal deposits, exhibits population heterogeneity reflecting the variability of hydrodynamic conditions and sediment sorting in this zone. The nearshore topography of tidal ridges, banks and troughs in these tidal seas leads to variable bed and tide- and storm-induced shear stress conditions. These conditions only allow for the mobilisation and onshore transport of some of the finer fractions (populations “b” and “c”), leaving an offshore mixture of these finer populations with coarser, less mobilisable sediments (population “a”). Once in the coastal zone, these two finer populations undergo further hydrodynamic sorting and segregation. Variably sorted very fine sands to silts (population “c”) are trapped in the low-energy estuarine-tidal flat sub-environment, while the highly homogeneous population “b” is further sorted in aeolian dune and beach sub-environments. This sorting occurs via a coastal sand transport pathway linking the Somme estuary mouth to the southern North Sea bight where tidal range and wave energy decrease relative to the English Channel. Since this sand transport pathway enables longshore transport of hydrodynamically sorted medium to fine sand derived directly from the immediate nearshore zone, it has further contributed to a net flux of this sand population from the eastern English Channel sea bed to the southern North Sea.     

The ethno-class trajectory of new neighborhoods in Israel

The subject of this article falls within the debate on the development of new neighborhoods beyond the hub of the metropolis and how this relates to planning from below. It regards new neighborhoods as being increasingly shaped through deliberate action in the form of public policy at the state and local levels. However, it emphasizes the central role of the government establishment, national institutions and ideologies in walling out and exclusionary practices. Research into four representative new neighborhoods in Israel, which were planned under the new spatial regime of the 1990s, reveals patterns of discrimination and ethno-class stratification that enable the preservation of nationalism and ethnic logic as the main, yet concealed, axis organizing social and spatial life.     

Hydrodynamics and sediment-transport in the nearshore of Poverty Bay, New Zealand: Observations of nearshore sediment segregation and oceanic storms

Nearshore regions act as an interface between the terrestrial environment and deeper waters. As such, they play important roles in the dispersal of fluvial sediment and the transport of sand to and from the shoreline. This study focused on the nearshore of Poverty Bay, New Zealand, and the processes controlling the dispersal of sediment from the main source, the Waipaoa River. Hydrodynamics and sediment-transport in water shallower than 15 m were observed from April through mid-September 2006. This deployment afforded observations during 3-4 periods of elevated river discharge and 5 dry storms.Similar wind, river discharge, wave, current, and turbidity patterns were characterized during three of the wet storms. At the beginning of each event, winds blew shoreward, increasing wave heights to 2-3 m within Poverty Bay. As the cyclonic storms moved through the system the winds reversed direction and became seaward, reducing the local wave height and orbital velocity while river discharge remained elevated. At these times, high river discharge and relatively small waves enabled fluvially derived suspended sediment to deposit in shallow water. Altimetry measurements indicated that at least 7 cm was deposited at a 15 m deep site during a single discharge event. Turbidity and seabed observations showed this deposition to be removed, however, as large swell waves from the Southern Ocean triggered resuspension of the material within three weeks of deposition. Consequently, two periods of dispersal were associated with each discharge pulse, one coinciding with fluvial delivery, and a second driven by wave resuspension a few weeks later. These observations of nearfield sediment deposition contradict current hypotheses of very limited sediment deposition in shallow water offshore of small mountainous rivers when floods and high-energy, large wave and fast current, oceanic conditions coincide.Consistently shoreward near-bed currents, observed along the 10 m isobath of Poverty Bay, were attributed to a combination of estuarine circulation, Stokes drift, and wind driven upwelling. Velocities measured at the 15 m isobath, however, were directed more alongshore and diverged from those at the 10 m isobath. The divergence in the currents observed at the 10 and 15 m locations seemed to facilitate segregation of coarse and fine sediment, with sand transported near-bed toward the beach, while suspended silts and clays were exported to deeper water.