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1.
Profound changes in international geopolitics and national policies, as well as global economic restructuring, and technological and communicational development have occurred since Chinatown first emerged. With the rapid pace of globalizing economy, increasing flows of population, commodities, information, and financial resources across the Pacific Rim – particularly in the last two decades – it is imperative that we reexamine the international migration patterns of Chinese population and reconceptualize the resulting Chinese settlement forms in the globalization era. This article attempts to serve such purposes by briefly reviewing the debate centered around historical and contemporary Chinatowns; discussing the impacts of societal and structural factors on Chinese immigration and settlement; presenting a spectrum of contemporary Chinese settlement forms in the United States, and highlighting some key characteristics. The article ends with brief discussion and conclusion sections that summarize some issues in contemporary Chinese community studies.  相似文献   

2.
Ivars Gutmanis 《GeoJournal》1995,37(2):257-266
In the post-Soviet era, the United States (US) is expected to contribute its military forces and defense resources in the event of need for Regional Conflicts and Operations Other Than War (OOTW). Such contributions may not be forthcoming. The principal reasons for the possible absence to the US contributions to maintain the New World Order is the paucity in the articulation of the US foreign and defense policies. The US public's well known preference for domestic policies, rather than foreign military and related operations, has been reinforced by the absence of the comprehensive explanation by the US political leaders of the US foreign and defense policies to the American people. The US military are preparing military doctrine for the possible engagements in the Regional Conflicts and OOTW, but these efforts are affected by the US well established past military doctrine to fight wars to a clear victory on the battlefield as well as by the absence of clear national military policy. American particulation in the future military operations — Regional Conflicts or OOTW — remains very much in doubt.  相似文献   

3.
High winds are one of the nation’s leading damage-producing storm conditions. They do not include winds from tornadoes, winter storms, nor hurricanes, but are strong winds generated by deep low pressure centers, by thunderstorms, or by air flow over mountain ranges. The annual average property and crop losses in the United States from windstorms are $379 million and windstorms during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km2. In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between 10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >$379 million and windstorms during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km2. In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between 10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >1 million, labeled catastrophes, during 1952–2006 totaled 176, an annual average of 3.2. Catastrophic windstorm losses were highest in the West and Northwest climate regions, the only form of severe weather in the United States with maximum losses on the West Coast. Most western storms occurred in the winter, a result of Pacific lows, and California has had 31 windstorm catastrophes, more than any other state. The national temporal distribution of catastrophic windstorms during 1952–2006 has a flat trend, but their losses display a distinct upward trend with time, peaking during 1996–2006.  相似文献   

4.
In 2004, the US Geological Survey (USGS) and the Geological Survey of Canada (GSC) initiated a pilot study that involved collection of more than 1500 soil samples from 221 sites along two continental transects across Canada and the United States. The pilot study was designed to test and refine protocols for a soil geochemical survey of North America. The two transects crossed a wide array of soil parent materials, soil ages, climatic conditions, landforms, land covers and land uses. Sample sites were selected randomly at approximately 40-km intervals from a population defined as all soils of the continent. At each site, soils representing 0 to 5 cm depth, and the O, A, and C horizons, if present, were collected and analyzed for their near-total content of over 40 major and trace elements. Soils from 0–5 cm depth were also collected for analysis of organic compounds. Results from the transects confirm that soil samples collected at a 40-km spacing reveal coherent, continental- to subcontinental-scale geochemical and mineralogical patterns that can be correlated to aspects of underlying soil parent material, soil age and climate influence. The geochemical data also demonstrate that at the continental-scale the dominance of any of these major factors that control soil geochemistry can change across the landscape. Along both transects, soil mineralogy and geochemistry change abruptly with changes in soil parent materials. However, the chemical influence of a soil’s parent material can be obscured by changing climatic conditions. For the transects, increasing precipitation from west to east and increasing temperature from north to south affect both soil mineralogy and geochemistry because of climate effects on soil weathering and leaching, and plant productivity. Regional anomalous metal concentrations can be linked to natural variations in soil parent materials, such as high Ni and Cr in soils developed on ultramafic rocks in California or high P in soils formed on weathered Ordovician limestones in central Kentucky. On local scales, anomalous metal concentrations recognized in soil profiles, such as high P in soils from animal confinement sites, are consistent with local anthropogenic disturbances. At a larger scale, the distribution of Hg across the west to east transect demonstrates that it can be difficult to distinguish between natural or anthropogenic contributions and that many factors can contribute to an element’s spatial distribution.Only three samples in a subset of seventy-three 0–5 cm depth soil samples from the north to south transect had organochlorine pesticides values above the method detection limit, apparently related to historic usage of the pesticides DDT and dieldrin.  相似文献   

5.
A unique historical data set describing the 142 storms each producing losses in excess of $100 million in the United States during the 1950–89 period were analyzed to describe their temporal characteristics. The storms caused $66.2 billion in losses (in 1991 values), 76% of the nation's insured storm losses in this period. These extreme storm catastrophes (SCs) were most prevalent in the south, southeast, northeast, and central U.S., with few in and west of the Rocky Mountains. Storm incidences were high in the 1950s, low in the 1960s-early 1970s, and increased in the 1980s. Losses due to SCs peaked in the 1950s, again in the late 1960s, with a lesser peak after 1985. The areal extent of storm losses peaked after 1975 and was least in the 1960s. The temporal variations of the three storm measures (incidence, losses, and extent) did not agree except when they all peaked in the 1950s. Regionally-derived time distributions of SCs showed a marked north-south differences in the United States with a U-shaped 40-year distribution in the northern half of the nation, and a relatively flat trend until a peak in the 1980s in the southern regions. The temporal distributions of hurricane-caused catastrophes differed regionally with occurrences in the prime areas, the southern, southeastern, and northeastern U.S., each quite different. Temporal distributions of thunderstorm and winter storm catastrophes were regionally more uniform.  相似文献   

6.
Book reviewed in this article:
Wright. H. E., Jr. (ed.) 1983: Late-Quaternary Environments of the United States . Vol. 1 The Late Pleistocene , edited by Stephen C. Porter.  相似文献   

7.
Tourism research in the United States: a geographic perspective   总被引:2,自引:0,他引:2  
The nature of tourism geography research in the United States is characterized by seven factors. First, research is not concentrated on a few topics of interest but rather is very diverse. Second, there is no research paradigm to influence the direction of investigations. Third, examination of tourism tends to stress the unique case rather than the general situation. Fourth, studies that replicate and/or verify original findings are not common. Fifth, the complexity of the tourism experience and the lack of data bases partially explain ideographic tendencies. Sixth, efforts to produce an understanding of the spatial aspects of tourism are primarily conducted by individuals and small groups. Seventh, emphasis is placed on domestic rather than international tourism. In conclusion, four future trends are noted. One, research that has been expanding rapidly will continue to increase but at a slower rate. Two, improved technology and methods of collecting information will make available large data sets for the assessment of tourism trends at international, national, regional, and state levels. Three, increased needs for useful research findings will result in more theoretical and applied investigations. Four, tourism geographers will engage in increased amounts of interdisciplinary research and begin to associate more and more with other social scientists in the examination of tourism.  相似文献   

8.
9.
Water and poverty in the United States   总被引:1,自引:0,他引:1  
Contrary to reports of 100% access to safe water and sanitation in international surveys, the United States (US) has a complex landscape of low-income water problems. This paper begins with a critical international perspective on water and poverty in the US. It shows that the US had a declining role in international water programs during the late-20th century, which contributed to limited international awareness of low-income water programs in the US, and limited US awareness of low-income water issues. To address the first problem, we provide an overview of low-income water programs in the US with an emphasis on those that serve small communities. We then examine census data on inadequate water systems in Colorado, which indicate that severe plumbing deficiencies persist despite these public water programs. Inadequate plumbing rates are lower than income poverty rates, however, which indicate partially successful strategies for achieving low-income water services. Analysis of local data in urban, rural, and mountainous areas of the state shows that poverty and water problems are correlated in complex ways, which has implications for all nations striving for universal access to safe water and sanitation.  相似文献   

10.
11.
Natural production of the radionuclide chlorine-36 (36Cl) has provided a valuable tracer for groundwater studies. The nuclear industry, especially the testing of thermonuclear weapons, has also produced large amounts of 36Cl that can be detected in many samples of groundwater. In order to be most useful in hydrologic studies, the natural production prior to 1952 should be distinguished from more recent artificial sources. The object of this study was to reconstruct the probable preanthropogenic levels of 36Cl in groundwater in the United States. Although significant local variations exist, they are superimposed on a broad regional pattern of 36Cl/Cl ratios in the United States. Owing to the influence of atmospherically transported ocean salt, natural ratios of 36Cl/total Cl are lowest near the coast and increase to a maximum in the central Rocky Mountains of the United States. Electronic Publication  相似文献   

12.
13.
The coal fields of the Unites States can be divided into six major provinces. The Appalachian and Interior Provinces contain dominantly bituminous coal in strata of Pennsylvanian age. The coal seams are relatively thin and are mined both by surface and underground methods. Sulfyur content is low to moderate in the Appalachian Province, generally high in the Interior province. The Gulf Coastal Plain Province, in Texas and neighboring states, contains lignite of Eocene age. The seams are 3–25 ft (0.9–7.5 m) thick and are minded in large open pits. The Northern Great Plains Province has lignite and subbituminous coal of Cretaceous, Paleocene and Eocene age. The coal, largely very low in sulfur, occurs in beds up to 100 ft (30 m) thick and is strip-mined. The Rocky Mountain Province contains a great variety of coal deposits in numerous separate intermontane basins. Most of it is low-sulfur subbituminous to bituminous coal iof Creatceous and early Tertiary age. The seams range from a few feet to over 100 ft (30 m) thick. Strip-mining dominates but underground mines are important in Utah and Colorado. The Pacific Coast Province, which includes Alaska, contains enormous cola resources but has seen little mining. The coal is highly diverse in physical character and geologic setting.  相似文献   

14.
Quaternary tectonic faulting in the Eastern United States   总被引:1,自引:0,他引:1  
Paleoseismological study of geologic features thought to result from Quaternary tectonic faulting can characterize the frequencies and sizes of large prehistoric and historical earthquakes, thereby improving the accuracy and precision of seismic-hazard assessments. Greater accuracy and precision can reduce the likelihood of both underprotection and unnecessary design and construction costs. Published studies proposed Quaternary tectonic faulting at 31 faults, folds, seismic zones, and fields of earthquake-induced liquefaction phenomena in the Appalachian Mountains and Coastal Plain. Of the 31 features, seven are of known origin. Four of the seven have nontectonic origins and the other three features are liquefaction fields caused by moderate to large historical and Holocene earthquakes in coastal South Carolina, including Charleston; the Central Virginia Seismic Zone; and the Newbury, Massachusetts, area. However, the causal faults of the three liquefaction fields remain unclear. Charleston has the highest hazard because of large Holocene earthquakes in that area, but the hazard is highly uncertain because the earthquakes are uncertainly located.Of the 31 features, the remaining 24 are of uncertain origin. They require additional work before they can be clearly attributed either to Quaternary tectonic faulting or to nontectonic causes. Of these 24, 14 features, most of them faults, have little or no published geologic evidence of Quaternary tectonic faulting that could indicate the likely occurrence of earthquakes larger than those observed historically. Three more features of the 24 were suggested to have had Quaternary tectonic faulting, but paleoseismological and other studies of them found no evidence of large prehistoric earthquakes. The final seven features of uncertain origin require further examination because all seven are in or near urban areas. They are the Moodus Seismic Zone (Hartford, Connecticut), Dobbs Ferry fault zone and Mosholu fault (New York City), Lancaster Seismic Zone and the epicenter of the shallow Cacoosing Valley earthquake (Lancaster and Reading, Pennsylvania), Kingston fault (central New Jersey between New York and Philadelphia), and Everona fault-Mountain Run fault zone (Washington, D.C., and Arlington and Alexandria, Virginia).  相似文献   

15.
Iron porphyrins have been isolated from seven U.S. humic coals of various geological ages. Mass spectrometry shows that for the higher rank coals the porphyrins comprise an homologous series of alkyl derivatives (C27-C32). Mesoheme is detected in a Cretaceous lignite from Montana.  相似文献   

16.
Present interest in environmental problems which are international, interstate or interprovincial in scope is drawing attention to the necessity for ecological regionalizations that will serve as a basis for intraregional transfer of experience. The major efforts at ecological regionalization by the national governmental agencies are described and compared. Although similar concepts have evolved in both countries, different systems of units have been developed for defining and mapping ecosystems at the regional scale. Before any regionalization is used it should be thoroughly tested, and modified if necessary.  相似文献   

17.
A database was compiled for the period 1977–2007 to assess the threat to life in the conterminous United States from nontornadic convective wind events. This study reveals the number of fatalities from these wind storms, their causes, and their unique spatial distributions. Nontornadic convective wind fatalities occur most frequently outdoors, in vehicles including aircraft, or while boating. Fatalities are most common in the Great Lakes and Northeast, with fewer fatalities observed in the central United States despite the climatological peak in severe thunderstorms in this region. Differences in fatality locations between tornadoes and nontornadic convective wind events highlight the unique combination of physical and social vulnerabilities involved in these deaths. Understanding these vulnerabilities is important to future reduction of nontornadic convective wind fatalities.  相似文献   

18.
Occurrence of mineral resources is directly or indirectly controlled by major tectonic processes. Additionally, similar mineral deposit types tend to be concentrated within geologically and tectonically similar areas. As a result, information on the production history of minerals in a well-explored and developed tectonic region—such as within the United States—can be used to estimate resources of geologically similar, underdeveloped tectonic areas elsewhere. For such application, two regions should be compared for geologic similarity using all available geologic information. Estimates of resources based on geologic analogy can be useful in large-scale mineral exploration programs where relatively little geologic information is available, such as in many developing countries. In this study, seven major tectonic regions within the United States are evaluated in terms of estimated mineral value as measured by historical mineral production and economic reserves. The seven regions assessed are: (1) Cordilleran Mountain Belt, (2) Colorado Plateau, (3) Central Stable Region, (4) Canadian Shield, (5) Ozark-Ouachtia Province, (6) Gulf and Atlantic Coastal Plain, and (7) Appalachian Mountain Belt. Regions are ranked in terms of estimated value of (1) 33 major mineral commodities, (2) nonfuel minerals, (3) hydrocarbons, and (4) individual mineral commodities. In terms of total value of historical mineral production and estimated economic reserve amounts of 33 major mineral commodities, the Gulf and Atlantic Coastal Plain is most valuable, with an estimated value of 1980 US$1,970,000/km2. Information on historical mineral production of U.S. tectonic regions may be useful in estimating resources in tectonically similar, underdeveloped regions elsewhere.  相似文献   

19.
This study reviews significant state and federal laws that can be used to protect karst, caves, and associated unique minerals and biota. The first state cave protection act was passed in Colorado in 1883; unfortunately it was repealed in 1971. From that modest beginning there are now a total of 22 states, Puerto Rico, and the Cherokee Nation that have specific cave protection acts. Most of these have been legislated during the last 20 years. There are a number of laws on the federal level that can be used for cave protection. The most important of these is the Federal Cave Resources Protection Act of 1988, which mandates cave conservation for many federal land management agencies. The Endangered Species Act of 1973 and the Federal Archaeological Resources Protection Act of 1976 can also be of significant use in the conservation of caves on federal land. The effects of these acts are variable. One factor is how important agency officials and law enforcement officers regard caves. It has not been unusual that little was done in the way of protection or prosecution even when the perpetrators have been apprehended. This attitude is changing rapidly primarily because those involved in enforcing the laws have been educated to the uniqueness and values of caves and their contents.  相似文献   

20.
Increasing losses of life and property and damages to the environment due to sleet and related winter storm conditions have increased the need for long-term sleet storm data to better assess the point and regional risks of sleet and their long-term variations. The areas of greatest losses and frequency of catastrophes caused by sleet during 1971–2007 are the Northeast and Central regions of the U.S. These two regions experienced 72% of all the nation’s sleet losses. Most of the western U.S. had no damaging sleet-related events or losses. When sleet losses occurred, they tended to be in 2, 3, or 4 adjacent states. Sleet catastrophes were most common in January with 15 of the 30 events. The earliest storm occurred in October and the latest in March. The temporal distributions of catastrophes and their losses during 1971–2007 were similar. Both showed a secondary peak in 1976–1979, a low in 1988–1991, and then high values during the 1996–2007 period. The temporal distributions of damaging storms and losses indicate an upward trend over time.  相似文献   

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