Deposition of annual growth lines in the apex of the common limpet (Patella vulgata) from Shetland Islands,UK and Norway: Evidence from field marking and shell mineral content of annual line deposition

The abundance, accessibility and value of limpets as a source of food and bait for coastal peoples have resulted in their high frequency in shell middens worldwide. The limpet Patella vulgata is found in middens from the Mediterranean to Norway, and morphometric and sclerochronological analyses of its shell can provide insight into harvesting patterns and paleoenvironmental variables valuable in reconstructing climate. Previous work with P. vulgata has relied on lines on the exterior of the shell, or on lines exiting on the shell surface in shell cross-section, as annual or sub-annual markers. Shell damage may compromise these lines and limit the use of some shells, but growth lines are also found in the better-preserved shell apex. We investigated whether the growth lines in the apex of P. vulgata from two locations in Northern Europe are annual using calcein-marking and recapture. Investigations were performed at one site in the Shetland Islands (UK) and at one site at the northern limit of P. vulgata's range in Northern Norway. We also used laser ablation to measure the concentration of minerals in the shells of two individuals from Shetland to determine if patterns of minerals suggested as bioproxies for temperature and productivity varied annually. All individuals deposited one growth line in the apex during their year in the field, and the lowest ratios of Sr/Ca and Ba/Ca and to a lesser extent Mg/Ca were coincident with annual lines on the shells from Shetland. Growth at both sites was modelled using the von Bertalanffy growth function, and apex growth was nearly five times faster in Shetland than in Norway, probably a result of differences in temperature between the two locations.     

Phase‐field modeling of epitaxial growth of polycrystalline quartz veins in hydrothermal experiments

Mineral precipitation in an open fracture plays a crucial role in the evolution of fracture permeability in rocks, and the microstructural development and precipitation rates are closely linked to fluid composition, the kind of host rock as well as temperature and pressure. In this study, we develop a continuum thermodynamic model to understand polycrystalline growth of quartz aggregates from the rock surface. The adapted multiphase‐field model takes into consideration both the absolute growth rate as a function of the driving force of the reaction (free energy differences between solid and liquid phases), and the equilibrium crystal shape (Wulff shape). In addition, we realize the anisotropic shape of the quartz crystal by introducing relative growth rates of the facets. The missing parameters of the model, including surface energy and relative growth rates, are determined by detailed analysis of the crystal shapes and crystallographic orientation of polycrystalline quartz aggregates in veins synthesized in previous hydrothermal experiments. The growth simulations were carried out for a single crystal and for grain aggregates from a rock surface. The single crystal simulation reveals the importance of crystal facetting on the growth rate; for example, growth velocity in the c‐axis direction drops by a factor of ~9 when the faceting is complete. The textures produced by the polycrystal simulations are similar to those observed in the hydrothermal experiments, including the number of surviving grains and crystallographic preferred orientations as a function of the distance from the rock wall. Our model and the methods to define its parameters provide a basis for further investigation of fracture sealing under varying conditions.     

论乡村地理学的对象、内容和理论框架

本文从历史、经验和理论三个角度论证了乡村地理学以乡村区域系统为研究对象。在对乡村区域系统特征分析的基础上概括出当代乡村地理学13个方面65个要点的基本研究内容,并偿试性地建构了以结构、进化和与环境关联为主体的乡村区域系统理论框架。     

论自然环境对人类社会发展作用方式

自然环境对人类社会发展的控制是一种可能性控制,这种控制的具体方式有四:一是经由自然稀缺性控制人类社会的持续发展;二是经由空间差异性控制人类社会的空间分化和区域发展;三是经由其时间上的变化控制人类社会发展的波动与周期;四是经由其使用价值的多样性控制资源与环境利用的社会选择范围与方向。作者对前两种方式做了重点论述。     

文化传播的空间基础及模式分析

本文从广义的文化背景出发,探讨了文化传播(扩散)的物质基础-信息-语言文化系统,以及文化传播与地理环境的相互关系,在此基础上,笔者对文化传播的空间模式进行了系统的分析。     

引进外资对中国工业化和经济结构变化的影响

本文从中国经济增长两个阶段的不同特点入手,分析了90年代中期以后中国大量引进外资的深层次原因。采用制造业增加值占GDP的比重作为衡量中国工业化进展程度的指标对整个90年代中国工业化的进程进行了实证分析,结果发现,中国的工业化从90年代中期以来实际上长期处于低速徘徊的阶段。大量引进外资导致中国工业化过程中存在两个明显的"替代效应",一是"外资替代效应",二是"弱质替代强质"现象。两个"替代效应"对中国工业化和经济结构变化的影响是极为深刻的。     

迁村并点理论与实践初探--以长安子午镇为例

迁村并点是解决三农问题、合理配置土地资源、消除城乡差别的重要手段,是实现区域空间整合的有效途径。本文对国内的迁村并点的研究现状进行了综述,以长安子午镇为例,通过对地域整体环境的把握,分析地域居民点之间的时空关系,提出区域整合的基本思路并对产业发展方向做了进一步的规划设想。     

湖南省区域趋同分析

根据区域趋同基本理论,采用新古典方法分析了湖南省区域趋同状况.结果表明,自我国实施社会主义市场经济体制以来,湖南省区域经济增长总体表现为条件趋同,趋同速度约为每年1.93%.受地理区位的影响,湖南省内部区域差异较大,国家发展政策对湖南省区域趋同的影响相当显著,例如,湘西自治州纳入西部大开发增强了湖南省区域增长的收敛性.而产业结构和投资状况对于区域经济增长的作用不强.在此基础上,提出几点促进湖南省区域趋同的对策.     

辽宁省城市基本公共服务质量差异的时空分析

基于基本公共服务的内涵,从教育服务、文化服务、卫生服务、基础设施服务、社会保障服务、生态环境服务和信息服务7个方面构建了基本公共服务质量评价指标体系,运用熵值法对2003-2011年辽宁省城市基本公共服务质量进行综合测度,并以此为变量,利用差异系数和基尼系数对辽宁省各市基本公共服务质量差异的演变过程与空间格局进行定量分析。结果发现:辽宁省各市基本公共服务质量整体为上升的趋势,表现出较为明显的规模特征,沈阳市和大连市两极突出;2003-2011辽宁省城市基本公共服务质量区域差异总体扩大的基础上,呈现先扩大后缩小的演变趋势,且以文化服务、卫生服务和基础设施服务的差异为主;空间上,公共服务质量空间提升极化作用不断增强,表现为不断向"沈阳-大连、盘锦-本溪"的"十字"轴线紧靠。     

基于夜间灯光数据的中国土地城镇化水平时空动态

基于长时间序列夜间灯光遥感数据,本研究从国家、八大经济区、省、地等四个尺度综合分析了中国1992-2010年土地城镇化水平时空动态特征。结果表明,在1992-2010年间:中国土地城镇化水平增长迅速,年均增长率为8.34%,明显高于同时期人口城镇化水平增长速度;土地城镇化水平区域差异十分显著,东部沿海经济区在八大经济区中土地城镇化水平最高且增长速度最快,香港、澳门特别行政区土地城镇化水平远高于其它省区;土地城镇化的热点区域主要集中分布于长三角、山东半岛、海峡西岸等11个城市群地区。