Spatial characteristics of exurban settlement pattern in the United States

Despite pervasive exurban development in the United States (US) over the last several decades, a lack of relatively precise data has hindered basic research, including classification of the types of emerging exurban settlement patterns. But because exurbia transcends the traditional dichotomy of urban versus rural and metropolitan versus nonmetropolitan, standard census data are of limited value in analyzing these regions. To address this gap, we made use of a spatially explicit population database to indentify and examine the configuration of exurban settlement. We developed a multidimensional spatial patch index, which captures the variation exurban settlement across the landscape, along the lines of shape, size and contiguity typology of exurban patches. This index reveals substantial heterogeneity in fine-scale pattern not reflected by aggregate measures of exurban settlement density.Using this index, we then explored to what extent metropolitan characteristics commonly believed to influence urban decentralization also are associated with the configuration of decentralization. We find that while large, contiguous clumps of exurban settlement are correlated with these metropolitan characteristics, other exurban pattern types (such as isolated or linear patches) are not. Therefore, it appears that the factors that contribute to more urban decentralization may also lead to greater contiguity and concentration of exurban settlement. Additionally, we find that the processes that lead to isolated and dispersed exurban settlement may be different from those that foster contiguous, concentrated exurban settlement.     

A national assessment of green infrastructure and change for the conterminous United States using morphological image processing

Green infrastructure is a popular framework for conservation planning. The main elements of green infrastructure are hubs and links. Hubs tend to be large areas of ‘natural’ vegetation and links tend to be linear features (e.g., streams) that connect hubs. Within the United States, green infrastructure projects can be characterized as: (1) reliant on classical geographic information system (GIS) techniques (e.g., overlay, buffering) for mapping; (2), mainly implemented by states and local jurisdictions; and (3) static assessments that do not routinely incorporate information on land-cover change. We introduce morphological spatial pattern analysis (MSPA) as a complementary way to map green infrastructure, extend the geographic scope to the conterminous United States, and incorporate land-cover change information. MSPA applies a series of image processing routines to a raster land-cover map to identify hubs, links, and related structural classes of land cover. We identified approximately 4000 large networks (>100 hubs) within the conterminous United States, of which approximately 10% crossed state boundaries. We also identified a net loss of up to 3.59 million ha of links and 1.72 million ha of hubs between 1992 and 2001. Our national assessment provides a backbone that states could use to coordinate their green infrastructure projects, and our incorporation of change illustrates the importance of land-cover dynamics for green infrastructure planning and assessment.     

Environmental factors influencing microcystin distribution and concentration in the Midwestern United States

During May–September 2000–2001, physicochemical data were collected from 241 lakes in Missouri, Iowa, northeastern Kansas, and southern Minnesota U.S.A., to determine the environmental variables associated with high concentrations of the cyanobacterial hepatotoxin microcystin (MC). The study region represents a south–north latitudinal gradient in increasing trophic status, with total phosphorus (TP) and total nitrogen (TN) values ranging between 2–995 and 90–15870 μg/L, respectively. Particulate MC values, measured by ELISA, ranged from undetectable to 4500 ng/L and increased with increasing latitude. Despite latitudinal trends, environmental variables explained <50% of the variation in MC values. Inspection of MC–TN and MC–Secchi bivariate plots revealed distinctly nonlinear trends, suggesting optima for maximum MC values. Nonlinear interval maxima regression indicated that MC–TN maxima were characterized by a unimodal curve, with maximal (>2000 ng/L) MC values occurring between 1500 and 4000 μg/L TN. Above 8000 μg/L TN all MC values were <150 ng/L. MC–Secchi maxima were characterized by exponential decline, with maximal MC values occurring at Secchi depths <2.5 m. The development of empirical relationships between environmental variables and MC values is critical to effective lake management and minimization of human health risks associated with the toxin. This study indicates MC values are linked to the physicochemical environment; however, the relationships are not traditional linear models.     

高昂的美国酒店特许经营费

对于酒店业主而言，加入酒店特许经营联盟费用不菲。但在当今酒店业激烈竞争的市场环境下，酒店特许经营能够让业主充分利用品牌的固有价值和已建立的市场地位，在更广的范围内提升入住率，并能够共享酒店连锁集团所创造的优势资源的实惠，牢牢吸引着酒店业主，让他们为加入酒店特许经营联盟许下重金。     

Development of normalization factors for Canada and the United States and comparison with European factors

In Life Cycle Assessment (LCA), normalization calculates the magnitude of an impact (midpoint or endpoint) relative to the total effect of a given reference.The goal of this work is to calculate normalization factors for Canada and the US and to compare them with existing European normalization factors. The differences between geographical areas were highlighted by identifying and comparing the main contributors to a given impact category in Canada, the US and Europe. This comparison verified that the main contributors in Europe and in the US are also present in the Canadian inventory. It also showed that normalized profiles are highly dependent on the selected reference due to differences in the industrial and economic activities. To meet practitioners' needs, Canadian normalization factors have been calculated using the characterization factors from LUCAS (Canadian), IMPACT 2002+ (European), and TRACI (US) respectively. The main sources of uncertainty related to Canadian NFs are data gaps (pesticides, metals) and aggregated data (metals, VOC), but the uncertainty related to CFs generally remains unknown. A final discussion is proposed based on the comparison of resource extraction and resource consumption and raises the question of the legitimacy of defining a country by its geographical borders.     

Homeless in the United States

The way public authorities presently define the homeless in the United States carries forward a complex historical legacy. The causal and moral assessments of the homeless, grounded in the work ethic of our capitalist society, have left behind four interpretations of the homeless as vagrant, deviant, sick or victim. Analysis of recent studies of the homeless, while uncovering the presence of all four definitions, found that most of the ‘new’ homeless are victims of the economy or sick.     

美国的城市规划法规体系

美国的城市规划有近百年的历史,规划法规体系十分完善,可以明确地分为联邦、州、地方3个层次.本文对各层次规划法规的主要内容、问题与特点、立法程序、负责机构进行了比较系统的概括,对各级规划法规的权限、纵向的调控管理、法规的实施监督做了相应的总结.为了更好地说明问题,本文列举了典型实例,并结合美国规划立法在近几年的改革和探索,有选择地介绍了一些最新的发展趋势和立法模式,旨在对我国规划法规的改革和现代化起到参考作用.     

美国的城市规划法规体系

美国的城市规划有近百年的历史,规划法规体系十分完善,可以明确地分为联邦、州、地方３个层次。本文对各层次规划法规的主要内容、问题与特点、立法程序、负责机构进行了比较系统的概括,对各级规划法规的权限、纵向的调控管理、法规的实施监督做了相应的总结。为了更好地说明问题,本文列举了典型实例,并结合美国规划立法在近几年的改革和探索,有选择地介绍了一些最新的发展趋势和立法模式,旨在对我国规划法规的改革和现代化起到参考作用。     

The Performance of Non-profit Housing Developments in the United States

Over the past two decades, non-profit organisations have played an increasingly important role in meeting the housing needs of low and moderate-income families. Not enough is known, however, about the performance of the housing developments sponsored by non-profit organisations. The purposes of the research described in this paper were: to assess the performance of a sample of housing developments sponsored by non-profit organisations in the US; to identify the factors that affect that performance and; to identify the lessons learned about effective project development and management. These questions are examined by studying the performance of 36 developments that received the Fannie Mae Foundation's Maxwell Award between 1989 and 1994. The results indicate that all the developments continue to provide decent, affordable housing for low-income persons. A major threat to the future viability of the rental and special needs developments, however, is the lack of adequate operating and replacement reserves. The most important factors in performance are stability in the leadership of the sponsoring organisations, local demand for affordable housing, the terms of the permanent financing and the screening and selection of tenants. Lessons learned from the experience of the developments studied and policy recommendations are presented.     

发达国家郊区发展系列谈之十美国的郊区——以奥兰治县和费尔法克斯县为例

一、“后郊区”：奥兰治县 奥兰治县（Orange County）是位于美国加利福尼亚州南部的一个县,濒临太平洋,在洛杉矶的东南部。面积2,455平方公里。2007年人口3,098,121人,是加利福尼亚州1人口第三大县,人口密度为1,392人／平方公里。     

美国质量管理一瞥

依据考察印象谈美国的质量管理情况。     

美国的灭火与救援机器人研发综述

设想某一个城镇生产木材调色板的流水线车间里 ,由于电器原因引发了一场火灾 ,致使建筑物坍塌。没有人能够确切地说出有多少工人被埋压在里面 ,更糟的是 ,当毗邻墙体坍塌时 ,隔壁的旧轮胎储藏室也被埋压在下面。于是市消防局派遣一批机器人去现场救援。第一个到达的机器人进入现场调查情况 ,该机器人能忍耐80 0℃的高温炙烤 ,身上安装了摄像机 ,可以给 90 m外的控制室发送图片 ,控制室的指挥人员就可以根据图片决定是否派消防队员冒险进入现场。第二个机器人是无人驾驶卡车 ,进入后便从 75 m远的地方以2 6 gal/ s的速度往火场喷水 ,并用它所…     

Public construction in the United States

This paper analyses the patterns of public sector construction expenditure in the United States for the 1957–1985 period. Expenditure trends of six categories of public works are analysed at three regional scales. Demand and supply factors influencing capital expenditures are briefly interpreted.     

美国对"棕地"的更新改造与再开发

为了促进"棕地"的更新改造与再开发,美国联邦政府制定了专门计划与一系列措施,不少地方政府也予以积极配合,力图以此推动地方经济的发展,并取得了一定的成效.尽管"棕地"问题对我们还是一个比较陌生的概念,但并不等于此类问题在我国还没有发生.