Industrial Structure and the Sources of Agglomeration Economies: Evidence from Manufacturing Plant Production

The impacts of agglomeration and local industrial structure are examined through an analysis of establishment‐level productivity. Using micro‐level data, measures of regional industrial specialization, economic diversity, and industrial competitive structure are incorporated together into a production function system estimated cross‐sectionally for three years and three manufacturing industries in the U.S. The findings demonstrate the importance of the influences of regional industrial competitive structure and diversity on performance.     

秦巴山区及毗邻地区野生百合性状描述

通过对秦巴山区及毗邻地区的野生百合性状的观察记载,运用主成分分析和聚类分析方法对68个性状的数量分析得出,影响百合分类的前几个主要性状群为：花的综合性状,叶的特征以及包括株高、茎粗、茎干硬度等种质指标及附属指标。而叶柄的有无、花梗长、鳞片颜色、茎干突起、花药长等指标是野生百合分类的重要性状。主成分分析和聚类分析选取的25个性状,能比较客观的反应种间的差别,将所观察的几种百合分成2组。结合观赏角度和园林应用方面,对百合的形态特征和生物学特性等进行描述。     

Agglomeration Economies and Employment Growth: New Evidence from the Information Technology Sector in Italy

This paper uses local labour market area (LLMA) data to investigate the dynamics of employment in the information technology (IT) sector in Italy between 2001 and 2005. The aim is to test if agglomeration forces might significantly affect local IT employment growth. The OLS results are broadly consistent with those of earlier studies. In particular, IT employment growth is enhanced by industrial diversity (Jacobs externalities) and by plant size (economies of scale). At the same time, LLMAs with higher IT concentrations are associated with lower employment growth rates. As a robustness check, quantile regression analysis is performed. This additional set of results reveals that the role of agglomeration forces is different across IT growth levels.     

Ranking State Environmental Outputs: Evidence from Panel Data

This paper uses state‐level pollution data from 1986–1997 to construct two indices that rank U.S. states according to environmental outputs. A major finding is that marginal performers in other indices, such as Wyoming, garner top spots in these ranking systems. The paper also presents findings from fixed and random effects models of panel data that imply state income levels are positively associated with environmental outputs after a threshold level of income is obtained.     

浙江西天目山及邻近地区种子植物生物多样性流研究

为研究天目山脉植物多样性流特征,采用区系地理成分、生物多样性容量与通量分析方法对该区龙王山、西天目和东天目3个自然保护区的种子植物进行分析。结果表明：3者的分布区类型在科级均以泛热带分布为主;在属级均以北温带分布为主;其植物区系均具有较为明显的过渡性特征。根据物种数及丰富度指数DG,西天目种子植物的生物多样性容量最大。3个保护区在连通性上,科的相似性系数均在70%以上,属的相似性略低,种的相似性除龙王山与西天目外均在50%以下,这表明天目山脉的不同保护区之间存在较为显著的种子植物分化。研究认为应该加强东天目的植物多样性保护与恢复,构建相应的生态廊道,这将有利于促进整个天目山脉生物多样性的保护。     

河北省太行山区石灰石矿区生态环境问题与生态复垦工程技术分析

矿山开采引发矿区生态退化与环境污染等一系列环境问题,严重制约了矿区社会经济的可持续发展。该文对河北省西部石灰石矿区环境问题进行分析的基础上,提出了适宜该矿区的生态复垦工程技术。     

Regional Marginal Costs and Cost Savings from Economies of Scale in Municipal Waste Treatment: An Application to the Chesapeake Bay Region

Marginal costs of removing effluent from waste treatment facilities are defined under different assumptions about regulatory policies. Marginal costs are different under a policy of uniform treatment for all plants compared to a least-cost policy, where different plants treat at different levels. The cost savings under these alternative policies are compared for river basins of the Chesapeake Bay when there are economies of scale in treatment costs. Current regulations for treatment plants in the Bay, which are not entirely uniform, are also compared to both the uniform and least-cost solutions. The potential savings from a least-cost policy are substantial for some basins.     

Discussion on the Environmental Protection and Planning of Traditional Villages

Resource environment of traditional villages is an important historical and cultural heritage of China. It deserves protection but currently is faced with severe destruction resulting from unsuccessful village planning or implementation. In this paper, problems existing in the planning of traditional villages are analyzed, and countermeasures for environmental protection and planning as well as proposals for implementation are put forward.     

沙河水库环境污染调查及其环境保护

监测了沙河水库的水质状况,结果表明：库区水质总体上符合Ⅱ类水标准,但是总磷在整个库区呈上升趋势,并全部超过Ⅱ类水质标准。污染源调查发现：农业生产中的化肥、农药淋失,生活垃圾排放是影响沙河水库水质的主要因素。论文还提出了水环境保护对策,以促进经济与环境保护的协调发展     

基于主成分和GIS 的关天经济区区域经济空间分异研究

在关中-天水经济区＂一核、一轴、三辐射＂的空间发展战略基础上,对经济区县域生产要素禀赋和生产技术水平等基本特征进行综合评价,据此划分区域并进行各区产业功能定位,以期为促进产业整合与升级和优化区域经济结构提供科学依据。运用多元统计的主成分分析,对研究区65个区（县）经济发展状况进行综合评价;运用区域分工指数和区位商衡量各县之间的产业集聚趋势,采用层次聚类法和GIS空间分析将经济区划分为5个区域;最后提出促进经济区地区分工及一体化,统筹区域经济发展的对策建议。     

The Impact of Real‐Time Information on Choices During the Commute Trip: Evidence from a Travel Simulator

ABSTRACT In the area of travel behavior, route choice when facing congestion has been widely researched. However, there are other behavioral alternatives based on people's activities and adaptive decision‐making strategies that have been overlooked. This paper focuses on how and what kind of information is used when considering a subset of these alternatives. Alternatives examined are the final choice of people's decision‐making process when faced with unexpected events during the commute trip in the presence of real‐time information collected using GABRIEL (Gis Activity‐Based tRavel sImuLator) in Columbus, OH. An empirical analysis of the data set, which includes a limited set of alternatives (six in total) is presented. Bivariate analysis and multinomial logit models are used to identify variables that influence the choice. Results show that people are willing to experiment with other alternatives if provided the information to support their choice.     

WTO框架下新疆棉花环境保护计划项目内容分析与探讨

依据WTO规则和新疆独特的自然生态条件,明确提出新疆棉花环境保护计划内容。通过在国内外多地实地考察调研,并与相关人员交流,同时查询相关文献资料(含统计数据、网上信息和政府文件等),了解WTO棉花补贴规则和新疆水资源、风沙、土壤盐碱化以及病虫草害等特点。新疆棉花环境保护计划包括新疆生态水供给、土地荒漠化治理、土壤改良和病虫草害生态防治四项内容,并阐述各项目设立理由与具体方案。为避免黄箱政策补贴引发的国际贸易纠纷,作者认为在新疆开展棉花环境保护计划行动十分必要,但由于WTO对环境保护补贴有明确的前置条件,再加上我国棉花环境保护补贴存在总量控制的现实问题,因而在落实环境保护计划方案时,应把环境保护计划与WTO 的其它补贴规则作为一个整体统筹考虑。     

The Impact of Environmental Regulations on the Industry Structure of Landfills

ABSTRACT Over the past twenty years, the environmental regulation of landfills has become increasingly restrictive both at the federal and state levels. Using a panel dataset of Ohio landfills, we developed a theoretical framework to explain the landfill operators’ responses to regulatory actions, and then estimate an empirical model of changes in industry structure. Because not all Ohio counties have landfill operations, we hypothesize that there is self‐selection in the location of landfills, which is accounted for with an appropriate econometric model. The study finds that environmental regulations had significant impact both on the location of landfill operations and concentration of the industry during the time period studied.     

Analysis of the Impact of DG on the Protection of Distribution System

The effects of DG on the protection of radial distribution system are discussed. With MATLAB/simulink software it builds distribution system model and DG model and calculates the current protection, according to the size and location of DG the effects on the short circuit current and protection of distribution system. The result shows the size of DG affects protection and makes it lose selectivity probably, DG upstream protection makes it amplify protection range, DG downstream protection makes it reduce protection range, and the original protections are necessary to install directional element.     

Status and Protection of National Wetland Parks in the Tibet Autonomous Region

This paper summarized the status, the brief history of the construction and development of national wetland parks in the Tibet Autonomous Region, and proposed corresponding measures for their later protection and development, in order to realize the sustainable development of national wetland parks.     

贵州高山生态区玉米新品种的特征特性与育种目标探讨

贵州高山生态区,包括毕节市和六盘水市海拔1400～2200 m之间的广大地区,玉米常年种植面积为24万hm2左右,是贵州省重要的玉米主产区之一,同时玉米作为该生态区最主要的粮食作物,产量的高低直接关系到粮食安全和农业生产的稳定发展.因此,选育和推广丰产性好的高产玉米新品种,长期以来都是促进当地玉米生产发展的重要技术措施.以毕节市为例,早在20世纪80年代初期就根据本地的自然生态条件、种质资源、农民对玉米的消费习惯和种植管理水平等,提出了以提高产量为主的“白色、大粒、硬粒”、“单交、三交、双交”配套的育种目标和育种方法,加上不断提出的对选育新品种的综合抗性和品质的要求,极大地推动了玉米新品种的选育推广和玉米生产水平的提高.