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71.
Paul C. Adams 《GeoJournal》2012,77(3):293-313
The broadening and deepening of Europe as a macro-region impels processes of expansion, contraction and transformation in sub-regions positioned within the EU and across the EU’s border. Recent arguments stress the idea of regionalization as a multi-layered process. Using Northern Europe as a study site, three such layers are explored: territorially bounded regionalization in the voting patterns of the Eurovision Song Contest, networked regionalization in the membership of intergovernmental organizations, and fluid regionalization in the geography of language. The associated regionalization processes are explained and visualized using mixed methodologies. Across these three layers of regionalization we can see the persistence of a Scandinavian core, but various territorial, networked and fluid forms of regionalization are stretching and pulling at the edges of Nordic regionalizations. 相似文献
72.
Alyson Cartwright Jay Quade Scott Stine Kenneth D. Adams Wallace Broecker Hai Cheng 《Quaternary Research》2011,76(3):430-440
Evidence from shoreline and deep-lake sediments show Laguna Cari-Laufquén, located at 41°S in central Argentina, rose and fell repeatedly during the late Quaternary. Our results show that a deep (> 38 m above modern lake level) lake persisted from no later than 28 ka to 19 ka, with the deepest lake phase from 27 to 22 ka. No evidence of highstands is found after 19 ka until the lake rose briefly in the last millennia to 12 m above the modern lake, before regressing to present levels. Laguna Cari-Laufquén broadly matches other regional records in showing last glacial maximum (LGM) highstands, but contrasts with sub-tropical lake records in South America where the hydrologic maximum occurred during deglaciation (17–10 ka). Our lake record from Cari-Laufquén mimics that of high-latitude records from the Northern Hemisphere. This points to a common cause for lake expansions, likely involving some combination of temperature depression and intensification of storminess in the westerlies belt of both hemispheres during the LGM. 相似文献
73.
Ted Goebel Bryan Hockett Kenneth D. Adams David Rhode Kelly Graf 《Quaternary International》2011,242(2):479-501
Global climate change associated with the onset of the Younger Dryas chronozone affected different regions of the northern hemisphere in different ways. In the Great Basin of western North America, the effect was positive for human populations. Relatively cool temperatures causing effectively wetter conditions filled some pluvial basins with shallow but permanent lakes and other basins with well-watered marshes or meadows. Vegetation communities dominated by sagebrush and grasses promoted healthy and diverse animal populations. Ten archaeological sites from the region have been dated to the Younger Dryas chronozone. Evidence from these sites indicates that Paleoindians with skull shapes and mitochondrial DNA similar to modern western North American Indians occupied the region. These early humans produced a material culture characterized predominantly by large stemmed bifacial points, although one site contained a small fluted point. Curated tool forms and technological activities represented in analyzed lithic assemblages suggest a highly mobile settlement strategy, and redundant short-term occupations of sites indicate frequent and long-distance residential moves across territories spanning distances of up to 400 km. Paleoindian subsistence pursuits focused on artiodactyls (primarily mule deer, bighorn sheep, and pronghorn antelope), leporids (chiefly jackrabbits), birds (sage grouse and waterfowl), insects (grasshoppers), and possibly fish. Easy-to-process plants like cactus pads were also eaten, but small seeds do not seem to have been an important part of Great Basin human diets until long after the Younger Dryas, closer to 9500 cal BP. The Great Basin record contains no evidence for natural catastrophe at the onset of the chronozone. Instead, the Younger Dryas appears to have been among the best of times for human foragers in this region of North America. 相似文献
74.
In this paper we analyze the effects of Faraday rotation on the azimuth of a transverse magnetic field as determined from the linear polarization in the inverse Zeeman effect. Observations of a simple sunspot were obtained with the Marshall Space Flight Center's vector magnetograph over the wavelength interval of 170 mÅ redward of line center of the Fe i 5250.22 Å spectral line to 170 mÅ to the blue, in steps of 10 mÅ. These data were analyzed to produce the variation of the azimuth as a function of wavelength at each pixel over the field of view of the sunspot. At selected locations in the sunspot, curves of the observed variation of azimuth with wavelength were compared with model calculations for the azimuth at each wavelength as derived from the inverse Zeeman effect modified by Faraday rotation. From these comparisons we derived the maximum amount of rotation as functions of both the magnitude and inclination of the sunspot's field. These results show that Faraday rotation of the azimuth will be a significant problem in observations taken near the center of a spectral line for fields as low as 1200 G and inclinations of the field in the range 20–80 deg. Conversely, they show that measurements taken in the wing of a spectral line are relatively free of the effects of Faraday rotation. 相似文献
75.
While considerable research has established the impacts of urbanization on streamflow, there has been little emphasis on how intra-annual variations in streamflow can deepen the understanding of hydrological processes in urban watersheds. This study fills this critical research gap by examining, at the monthly scale, correlations between land-cover and streamflow, differences in streamflow metrics between urban and rural watersheds, and the potential for the inflow and infiltration (I&I) of extraneous water into sewers to reduce streamflow. We use data from 90 watersheds in the Atlanta, GA region over the 2013–2019 period to accomplish our objectives. Similar to other urban areas in temperate climates, Atlanta has a soil-water surplus in winter and a soil-water deficit in summer. Our results show urban watersheds have less streamflow seasonality than do rural watersheds. Compared to rural watersheds, urban watersheds have a much larger frequency of high-flow days during July–October. This is caused by increased impervious cover decreasing the importance of antecedent soil moisture in producing runoff. Urban watersheds have lower baseflows than rural watersheds during December–April but have baseflows equal to or larger than baseflows in rural watersheds during July–October. Intra-annual variations in effluent data from wastewater treatment plants provide evidence that I&I is a major cause of the relatively low baseflows during December–April. The relatively high baseflows in urban watersheds during July–October are likely caused by reduced evapotranspiration and the inflow of municipal water. The above seasonal aspects of urban effects on streamflow should be applicable to most urban watersheds with temperate climates. 相似文献
76.
John R. Letaw J. H. Adams Jr. Rein Silberberg C. H. Tsao 《Astrophysics and Space Science》1985,114(2):365-379
Cosmic-ray nuclei are close to fully ionized during their passage through the Galaxy. Electron capture decay is rare among these nuclides because most do not have bound electrons. Under certain conditions, specifically low energies and/or high charges, electron capture becomes an essential factor in determining cosmic-ray composition. In this paper we discuss the general nature of electron capture decay in cosmic rays and describe specific measurements which can reveal the existence of electron capture decay, and energy and density-dependent processes in the interstellar medium. 相似文献
77.
78.
Research has documented how grass-roots activists deploy the environmental justice frame to convey their grievances and demand their right to health and safety. While scholars have highlighted the widespread success of this frame, little attention has been paid to instances where the environmental justice frame fails to resonate. Drawing from social movements and environmental justice literatures, we examine how local discursive and cultural contexts can pose barriers to environmental justice claims. Our case is based on legacy pollution from a decommissioned creosote facility in Southern Mississippi. When black residents discovered the pollution in their neighborhood, they made repeated appeals to authorities for remediation and compensation. After being denied inclusion in a lawsuit filed by white residents, they formed an environmental justice organization to mobilize support for their campaign. Findings reveal the importance of both historical contextualization and the social situation of frame deployers in analyses of the environmental justice frame. 相似文献
79.
80.
The magnitude m bLg 5.0 Mont-Laurier earthquake of 1990 October 19, in Quebec, Canada, was one of the largest to have occurred in eastern North America during the past decade. High-frequency ground motions recorded on regional network instruments exceeded values anticipated for an event of its size by a factor of 3. A commonly favoured explanation for the discrepancy is that the source was a rare 'high-stress' event. In this paper, detailed fault-slip models are derived to fit waveform and spectral characteristics of the regional data. The results establish that the effective rupture stress was normal (about 100 bars), that the fault rupture developed asymmetrically, and that the average slip time for points inside the rupture area (approx. 0.1 s) was significantly less than that associated with the standard Brune (1970) source spectral model. The rupture area developed in at least four distinct episodes, each extending the previously ruptured area. Taken together with similar results for the m bLg 6.5 Saguenay earthquake of 1988 November, the results indicate that a widely used assumption in hazard analyses, that earthquake spectra are adequately represented by the standard Brune spectral model, is unreliable for the interpretation and prediction of strong ground motion. 相似文献