Share-Shift Analysis of Geo-Economic Pattern on Global Cereal Crops in Recent 50 Years

In recent 50 years, with the rapid development of international food trade, the geoeconomic pattern of cereal crops has changed tremendously which produced a significant impact on global food security. This paper attempted to analysis the production pattern and trade pattern of global cereals, especially three main crops of wheat, maize and rice by using the method of share-shift. Given the fact of almost every economic phenomenon is driven by their economic return behind them, this paper attempted to a further step into their economic pattern by examining their net trade flow. The results showed that from the view of production and trade, the geographic pattern of global cereals has changed greatly which can be described as developing countries has replaced developed countries and become the world’s biggest cereals production and trading area. But when moving to the net trade flow, it turns out to be another story that can depicted as the regional fixation features of economic returns which can be convinced from the labor division of global cereals trade, among which developed countries acts as net trade profit area while developing countries as net trade output area, and their gap between net export and net import has been widening from the view of evolution trend. So what we learn from the evolution of geoeconomic pattern on this topic is that our place in global cereals trade system, and therefore alert us to concern not only on the pattern transition but also the economic meaning behind it, only by doing so can we learn to plan our food future more wisely and effectively.     

江汉平原建设用地扩张的时空特征与驱动力分析

建设用地的迅速扩张已经成为当前中国土地利用变化的主要特征。以中国科学院土地利用数据库（基于1995、2000和2005TM影像）为基础,利用GIS空间叠加分析和缓冲区分析技术,提取建设用地变化及其空间分布信息,运用建设用地扩张速度和强度指数对江汉平原1995～2005年10 a来建设用地扩张的时空特征进行了研究。在此基础上,结合各县市的社会经济等信息,运用灰色关联分析,对建设用地扩张的驱动力进行探讨。结果显示：总体上江汉平原建设用地扩张速度呈现增大趋势,但各县市之间扩张差异显著;各县市建设用地扩张分布上呈现组团状特点;沿交通线扩张的特征较为突出,尤其是后一阶段增幅高于前一阶段,沿江扩张增幅明显;总人口的增长是江汉平原建设用地扩张最主要的驱动力;交通条件改善、经济发展与区域建设用地扩张也有明显的相关关系     

中国高新技术产业的地理格局与地理集中

与传统产业相比,高新技术产业对地理集中具有更加强烈的内在要求,这导致其地理格局与传统产业具有明显的差别。在产业集中指数等相关理论方法和实证分析的基础上,力图从地理学视角,结合高新技术产业的时间序列数据和2008年断面数据,从整体产业和分行业研究了高新技术产业地理格局和地理集中的现状和变动趋势。研究发现,我国高新技术产业高度集中在沿海省区和陕、川两省,省区间差距悬殊;高新技术产业产值份额同经济发展显著相关。时间序列分析表明：长时间尺度产业集中持续增强,近年来趋于稳定;地理格局逐渐清晰,核心省区凸显。不同行业由于产业性质、发展基础、资源需求和市场群体的差异,有其各自的集中态势和演变趋势。     

In silico prediction of Tetrahymena pyriformis toxicity for diverse industrial chemicals with substructure pattern recognition and machine learning methods

There is an increasing need for the rapid safety assessment of chemicals by both industries and regulatory agencies throughout the world. In silico techniques are practical alternatives in the environmental hazard assessment. It is especially true to address the persistence, bioaccumulative and toxicity potentials of organic chemicals. Tetrahymena pyriformis toxicity is often used as a toxic endpoint. In this study, 1571 diverse unique chemicals were collected from the literature and composed of the largest diverse data set for T. pyriformis toxicity. Classification predictive models of T. pyriformis toxicity were developed by substructure pattern recognition and different machine learning methods, including support vector machine (SVM), C4.5 decision tree, k-nearest neighbors and random forest. The results of a 5-fold cross-validation showed that the SVM method performed better than other algorithms. The overall predictive accuracies of the SVM classification model with radial basis functions kernel was 92.2% for the 5-fold cross-validation and 92.6% for the external validation set, respectively. Furthermore, several representative substructure patterns for characterizing T. pyriformis toxicity were also identified via the information gain analysis methods.     

农牧交错带生态经济耦合评价模型及其实证研究

生态经济耦合评价模型是揭示生态与经济互动关系及其系统耦合要素演变过程的一种有效分析方法,农牧模式的生态经济耦合评价模型是开展农牧交错带生态经济可持续发展定量研究的有效手段.本研究基于生态经济耦合评价模型,以陕西省吴起县为例,利用黄土丘陵沟壑区各监测站数据和吴起县2007年土地利用现状、地形、坡度等数据,模拟分析了吴起县种植业作物产量与泥沙流失量随人均梯田面积的变化特征,评价了吴起县草畜业生态经济耦合现状并模拟分析了预计可达到的生态经济耦合指数.结果表明:坡耕地改梯田不仅能小幅度增加作物产量,而且能大幅度减少泥沙流失量,具有显著的生态经济效益;生态经济耦合指数可以定量表征生态经济耦合过程及其状态,吴起县目前农牧模式生态经济耦合过程还处在相对较低的水平,草畜业模拟生态经济耦合指数仅为992.20 元/t,大规模开展舍饲草畜业不可行,未来需在加强草场管理和合理载畜的前提下,逐步取消禁牧(放养羊)政策.     

Eld’s Deer Translocated to Human-Inhabited Areas Become Nocturnal

As human populations expand and nonhuman animals decline, understanding the interactions between people and wildlife is essential. For endangered species, appreciating the effect of human disturbance can be important for their conservation. However, a human disturbance angle is often absent from ecological research, despite growing evidence of the negative impact of nonfatal human interference. Here, we monitored Hainan Eld’s deer living within a reserve and translocated animals living amongst villagers. We show that translocated deer deviated from a crepuscular activity pattern and became increasingly nocturnal, and most active when villagers were not. It appears that translocated deer adapted over time to human disturbance and this pattern is similar to that of other species during periods of hunting. People do not pose an actual threat to Eld’s deer, but their presence triggered a response akin to predator avoidance and may be interfering with broader aspects of their biology and conservation.     

华北平原冬小麦-夏玉米种植模式碳足迹研究

农业碳足迹理论可以系统评价农业生产过程中人为因素引起的碳排放,是构建低碳农业的理论基础,对实现低碳农业其有重要的指导意义.为探明农业生产中的碳足迹,本文基于河北吴桥县农户生产调查数据,利用农业碳足迹理论及研究方法,评价了华北平原冬小麦-夏玉米两熟种植模式的碳足迹.结果表明:冬小麦-夏玉米种植模式碳足迹的大小为1 737.37±337.02 kgCe/hm2·a,生产1 kg粮食的碳成本是0.12±0.03 kgCe,其中冬小麦的碳足迹是1 101.31±251.91 kgCe/hm2·a,小麦的碳成本是0.16±0.04kgCe/kg,夏玉米的碳足迹是636.06±163.90 kgCe/hm2·a,玉米的碳成本是0.08±0.02 kgCe/kg.冬小麦-夏玉米种植模式碳足迹的组成中,化肥占总量的61.76％,电能占25.03％,柴油占7.44％,种子占4.75％,农药占1.02％.同时,发现N肥的施用量和电能消耗量均与碳足迹有正相关性,种植规模与碳成本有负相关性.因此,构建节肥、节水及规模化的低碳种植模式是实现华北平原农业节能减排的重要途径.     

基于模糊模式识别的系统安全模糊综合评价

针对模糊综合评价的不足之处,提出把权广义距离之和模糊模式识别运用到模糊综合评价当中,建立了基于模糊模式识别的模糊综合评价模型.通过对陕西某高层建筑火灾危险评价实例证明,该模型能使系统安全评价结果更准确、合理.     

秦皇岛市土地利用结构与土壤侵蚀空间格局分析

利用3S技术和景观生态学原理,以小流域为单元对秦皇岛市土地利用结构和土壤侵蚀等级类型进行空间分析,得出了不同土地利用结构所占面积和不同土壤侵蚀类型所占面积及分布小流域,并详细分析了秦皇岛市土壤侵蚀的主要影响因子和不同土地利用结构侵蚀现状。     

安庆沿江湿地景观格局变化及其驱动力

湿地具有重要的环境和生态功能,安庆沿江湿地自然保护区以其良好的自然性,正成为学术界关注的焦点和热点。基于1988、2006年两期TM遥感影像数据,借助于RS/GIS工具,获取安庆沿江湿地的景观斑块数据,运用Fragstats景观格局分析软件探讨了近20年来安庆沿江湿地景观格局的动态变化特征,研究结果表明：(1)安庆沿江湿地以湖泊和滩涂沼泽为主要景观类型;(2)研究期内湿地景观面积发生了较大幅度的缩减,各湿地景观类型间的动态变化较显著,以湖泊的萎缩变化最明显;(3)安庆沿江湿地景观在空间配置上趋于破碎和零散,景观斑块边界的复杂性程度和不规则程度在逐渐下降,形状趋于规整,景观类型结构和数量趋于均衡,景观斑块间连接程度有所降低。进一步探讨其驱动力因素,认为主要受到研究区内人口密度、农业开发活动、国家和区域政策法规以及湖区农户湿地环境保护意识等因素的影响。