共查询到20条相似文献，搜索用时 31 毫秒
1.
生物质能源生产的生态环境影响(英文) 总被引：1，自引：0，他引：1
生物质能源生产是能源发展领域的重大挑战,在解决新的替代能源中扮演着重要角色。本文着重论述了美国生物能源生产的生态环境问题。从经济、环境和战略方面考虑,生物能源有望提高国家安全,因而受政策驱动的美国生物能源生产技术备受注目。尽管生物能源具有诸多潜在效益,但是在北美,生物原料供应、高强度经营的土地上农药使用及其对陆地野生动物的潜在影响等令人担忧,我们分析了其中的原因。通常认为,未来生物能源的环境、经济效应是正面的;然而,谨慎地审视和发展生物能源经济以保护生态系统的可持续性显得至关重要。 相似文献
2.
3.
David Pimentel 《Natural Resources Research》2003,12(2):127-134
Several studies suggest that the $1.4 billion in government subsidies are encouraging the ethanol program without substantial benefits to the U.S. economy. Large ethanol industries and a few U.S. government agencies, such as the USDA, support the production of ethanol. Corn-farmers receive minimal profits. In the U.S. ethanol system, considerably more energy, including high-grade fossil fuel, is required to produce ethanol than is available in the energy-ethanol output. Specifically about 29% more energy is used to produce a gallon of ethanol than the energy in a gallon of ethanol. Fossil energy powers corn production and the fermentation/distillation processes. Increasing subsidized ethanol production will take more feed from livestock production, and is estimated to currently cost consumers an additional $1 billion per year. Ethanol production increases environmental degradation. Corn production causes more total soil erosion than any other crop. Also, corn production uses more insecticides, herbicides, and nitrogen fertilizers than any other crop. All these factors degrade the agricultural and natural environment and contribute to water pollution and air pollution. Increasing the cost of food and diverting human food resources to the costly inefficient production of ethanol fuel raise major ethical questions. These occur at a time when more than half of the world's population is malnourished. The ethical priority for corn and other food crops should be for food and feed. Subsidized ethanol produced from U.S. corn is not a renewable energy source. 相似文献
4.
《Urban geography》2013,34(3):258-278
An information theoretic model is used to compare the evolution of the spatial distribution of corporate headquarters in the United States during the period 1957- 1979 with an ideal time-space model. Dispersion of headquarters across the regions of the U.S. has been the dominant trend for most subsectors of the economy since the mid-1960s. Corporate concentration has been a compensatory trend that has left the overall system dispersion of headquarter location at a stable and unchanging level for the country as a whole. 相似文献
5.
David Wilson 《The Professional geographer》2013,65(2):139-149
This discussion hones and refines one conceptual orientation in geography and urban studies increasingly used to understand racialized poverty and marginalization in U.S. cities: racial economy. The article illuminates two aspects of this perspective, as an ongoing ontological project with six dominant features and as a base of epistemological understandings about contemporary racialized realities in current U.S. cities and society. This discussion shows racial economy to be still developing and in need of deeper theorizing. 相似文献
6.
Univariate indicators such as employment are often used to benchmark economic growth at the local and regional levels. However, the tremendous technological and industrial changes in the U.S. economy in the second half of the twentieth century suggest this practice may be outdated. In fact, the singular use of univariate indicators to benchmark regional development may obscure a much richer and more complex web of economic processes. Given the potential complexities associated with regional benchmarking in the current global economy, this paper will explore the numerical differences in economic performance presented by popular univariate indicators of regional growth. Results demonstrate a univariate approach to benchmarking presents an incomplete snapshot of regional performance that is incapable of capturing the multifaceted nature of economic growth in today’s global knowledge economy. Although job creation remains an important component to development efforts, many other factors should be considered in evaluations of regional performance, including the industries in which jobs are created and their associated wages. 相似文献
7.
J. Dennis Lord 《The Professional geographer》1984,36(1):51-63
Considerable instability exists among large U.S. metropolitan areas in their status as wholesale trade centers. Differences in wholesale trade growth rates, changes in national shares, and shifts in rank position reflect not only population growth patterns, but also structural changes in the national economy. In the latter instance, the wholesale product mix of SMSAs is an important factor in explaining their differential fortunes within the wholesaling hierarchy. 相似文献
8.
前苏联是世界上铁路运输利用率最高的国家。本文从其铁路发展的背景条件出发，分析了铁路成为前苏联最主要运输方式的原因，并进一步探讨了前苏联铁路网的建设、发展和分布特点，对我国正在进行的大规模铁路建设有一定借鉴意义。 相似文献
9.
LAUREL J. HUMMEL 《Geographical review》2005,95(1):47-72
ABSTRACT. Alaska was strategically key to the U.S. defense plan during the cold war (1946–1989). As such, it was the scene of an enormous and sustained military investment, the effect of which was amplified by Alaska's undiversified economy, sparse development, small resident population, and marginalized political status at the beginning of the era. The strong military presence affected Alaskan demographics, economic development, and infrastructure and figured prominently in the admission of Alaska to the union in 1959. The high profile and long‐term presence of the U.S. military had such a dramatic affect on the course of Alaska that the result was tantamount to a “militarized landscape.” 相似文献
10.
Raines G. L. Zientek M. L. Causey J. D. Boleneus D. E. 《Natural Resources Research》2002,11(3):167-186
For public land management in Idaho and western Montana, the U.S. Forest Service (USFS) has requested that the U.S. Geological Survey (USGS) predict where mineral-related activity will occur in the next decade. Cellular automata provide an approach to simulation of this human activity. Cellular automata (CA) are defined by an array of cells, which evolve by a simple transition rule, the automaton. Based on exploration trends, we assume that future exploration will focus in areas of past exploration. Spatial-temporal information about mineral-related activity, that is permits issued by USFS and Bureau of Land Management (BLM) in the last decade, and spatial information about undiscovered resources, provide a basis to calibrate a CA. The CA implemented is a modified annealed voting rule that simulates mineral-related activity with spatial and temporal resolution of 1 mi2 and 1 year based on activity from 1989 to 1998. For this CA, the state of the economy and exploration technology is assumed constant for the next decade. The calibrated CA reproduces the 1989–1998-permit activity with an agreement of 94%, which increases to 98% within one year. Analysis of the confusion matrix and kappa correlation statistics indicates that the CA underestimates high activity and overestimates low activity. Spatially, the major differences between the actual and calculated activity are that the calculated activity occurs in a slightly larger number of small patches and is slightly more uneven than the actual activity. Using the calibrated CA in a Monte Carlo simulation projecting from 1998 to 2010, an estimate of the probability of mineral activity shows high levels of activity in Boise, Caribou, Elmore, Lincoln, and western Valley counties in Idaho and Beaverhead, Madison, and Stillwater counties in Montana, and generally low activity elsewhere. 相似文献
11.
大国力量均势与东北亚格局 总被引：2，自引：1，他引：2
冷战后，国际安全格局与世界经济形势发生出深刻变化。雅尔塔体系的瓦解，将东北亚维持了半个多世纪的平衡格局打破，随着21世纪美国全球战略重心由欧洲大西洋岸向西太平洋，东北亚更成为新世纪大国力量角逐，寻求新的平衡的热点区域。我国地处东北亚的腹地，其政治经济格局的演化与调整均对我国政治经济产生重大影响。因而，分析研究东北亚地萄政治经济安全态势，有利于我国在新世纪争取更大的生存发展空间。 相似文献
12.
JULIE A. TUASON 《Geographical review》1999,89(1):34-53
ABSTRACT. Between 1898 and 1908 the National Geographic Magazine reported copiously on the territorial acquisition and U.S. colonial administration of the Philippines after the Spanish-American War. The pages of the magazine provide an intriguing window on connections between the emergence of geography as an organized profession and the expanding sphere of U.S. control of overseas territories. The overall picture reveals a shift from bold calls for direct economic exploitation of the natural resources and labor power of the Philippine Islands to more platitudinous justifications for U.S. control, based on moral responsibility and the ostensibly objective imperatives of “scientific” development. 相似文献
13.
Population Change in U.S. Cities: Estimating and Explaining the Extent of Decline and Level of Resurgence 总被引：1，自引：0，他引：1
The revalorization of the U.S. metropolis and restructuring of the U.S. economy are leading to increasingly complex patterns of population growth and decline. In this article we provide an empirical context for understanding the embodied nature of these changes by analyzing the long-term, demographic changes for the 100 largest cities. In terms of population change we identify four model urban types: steady decline, continuous increase, growth interrupted, and slowly resurgent. We consider, in detail, cities where population decline has halted and others where there are indications of population resurgence. The article focuses on these resurgent cities, provides some causal explanations, discusses the role of gentrification, and explores policy implications. 相似文献
14.
William G. Moseley 《The Professional geographer》2019,71(1):152-156
My overarching argument in this article is that the United States is no different than any other country in the world in that its population has elected good leaders and bad. As in other places, global and national neoliberal economic reforms have affected the U.S. economy, hallowing out the manufacturing sector, shrinking government and social safety nets, and fostering income inequality. This has left various U.S. publics struggling to make ends meet and vulnerable to demagoguery. Although the country prides itself on the strength of its institutions, institutions are no more than social contracts that need to be assiduously maintained by civil society. Although there is a strong “ivory tower” tradition in U.S. academe, the republic needs scholars—acting as public intellectuals—to fully participate in civic debates if it is to have a sufficiently robust civil society that maintains and defends its democracy and institutions. This article is divided into three sections. First, I briefly review the Trump administration's proposals for international development and diplomacy, giving particular attention to these issues in the African context. Second, I present an argument for why the United States needs public intellectuals now more than ever. Third, I share some concrete advice on how geographers might better connect with various publics. 相似文献
15.
县域经济是区域经济中的重要的一环，是中国建设全面小康社会的基本载体，是未来中国提高综合国力、参与国际竞争的生力军，搞好县域经济对振兴西部经济具有重大意义。从优化产业结构、选择适宜主导产业人手，以高县这一典型的西部丘陵低山县为例，对高县的经济和产业结构现状进行了阐述，利用计算机spss软件分析了其发展中存在的问题，提出了产业结构优化调整的方向，定性和定量地分析了高县的产业结构，利用特尔费法确定了高县的主导产业为煤化工并做了必要的分析。对高县“十一五”期间的国民经济发展具有具体的指导意义，对发展西部山区经济具有一定的借鉴。 相似文献
16.
Thomas M. Gunther 《Natural Resources Research》1992,1(4):267-280
Quantitative assessments and analyses of mineral resources can provide important input to decisions affecting public lands. This article, a companion article to Spanski, 1992, presents an application of resource assessment and analysis tools developed by the U.S. Bureau of Mines and the U.S. Geological Survey to U.S. Forest Service lands in northwest Montana. The analytical system described here integrates mineral deposit models, mine and mill cost-estimation models, and relevant economic and policy assumptions to estimate potential mineral production and the associated direct and indirect mineral-related economic impacts that could follow development of minerals. Finally, the impacts of land-use policies are estimated using the model. 相似文献
17.
19世纪末20世纪初,美国成为世界第一大经济体,亟须开辟海外新市场。为了争夺当时被认为是潜在的“最大的世界市场”,美国侵占西班牙在南海东岸的殖民地菲律宾,将其作为进入中国市场的据点,这是美国对南海地缘的最初认知。在以后的30多年时间里,美国都没有染指南海,直到日本侵略东南亚。日本把东南亚纳入“大东亚共荣圈”,利用南海地缘优势攻击美军,使南海首次呈现重要的地缘战略价值。南海地缘的新变化促使美国重新认知南海。此后,随着“边缘地带论”的兴起,美国越发重视南海的地缘战略价值,并谋求为自己的国家利益服务。进入20世纪50年代,亚太形成了截然对立的以中国为首的社会主义阵营和以美国为首的资本主义阵营。遏制共产主义在亚太扩张成为美国推行霸权战略的总方针。这直接影响美国对南海的地缘战略认知,利用南海的地缘战略价值围堵遏制中国就成为美国对华政策的必然选项。 相似文献
18.
Steven M. Fortier Christine L. Thomas Erin A. McCullough Amy C. Tolcin 《Natural Resources Research》2018,27(2):191-200
The U.S. Geological Survey National Minerals Information Center (NMIC) is the U.S. Government agency tasked with the collection, analysis, and dissemination of information on the production, consumption, import, export, and other measures of the flows of non-fuel mineral commodities of importance to the U.S. economy and national security. The NMIC and its agency predecessors have maintained a database of this information, collected and published annually, dating back to the beginning of the twentieth century. Time series analysis of annual information from the NMIC provides the opportunity to identify trends in the supply chains of the minerals and metals which are increasingly in demand for advanced technologies. The identification of trends in data for net import reliance, country concentration of production, global demand, price volatility, and other measures, when combined with world governance indicators, can be used to focus attention on individual mineral commodities where supply chain restrictions may develop. Specific examples for U.S. net import reliance, global tantalum primary mining, and mineral criticality screening are presented to illustrate the utility of time series analysis of trends in mineral commodity supply and demand, the types of data required, and the limitations of currently available information. 相似文献
19.
国际直接投资变化趋势及对我国引资的思考 总被引：1，自引：0，他引：1
国际资本投资特别是对外直接投资的迅速增长，无论是对资本输出国还是对资本吸纳国的经济和社会发展都产生了深刻的影响。以美国为首的发达国家无论是在资本输出还是资本流入中一直都占据重要地位，以新兴市场国家为代表的发展中国家的国际资本投资存在逐渐加强的趋势。从国际资本投资的行业分布特征来看，主要集中在制造业和金融、保险、房地产业，特别是金融、保险和房地产业所占比重持续上升。改革开放以来，外商投资已经成为引发我国经济发展深刻变化的重要因素，外商投资企业成为我国国民经济中的重要组成部分。要进一步抓对全球经济一体化的机会，制定相应的发展战略，促进我国经济的发展。 相似文献
20.
美国的区域政策及其对我国西部开发的启示 总被引：5，自引：0，他引：5
本文分析了美国区域政策的特点：区域政策的核心是提高受援地区的社会福利;致力于改善落后的投资环境;突出重点,实施增长中心战略;注重培育欠发达地区的自我发展能力;依靠法制化管理,保障援阻工作顺利进行。在此基础上,提出解决我国地区发展不平衡问题的一些措施。 相似文献