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721.
José Carlos G. Aguiar 《Singapore journal of tropical geography》2012,33(2):171-183
The vision of a borderless world, of people, ideas and products freely circulating within a self‐regulating market, is one that clashes with the emerging legal regime based on the punitive force of the state. After a period of liberalization, seen in the opening of national economies and the promotion of regional trade projects and free‐trade zones, the ambivalence of neoliberalism is manifest in a borderless capitalism that ambiguously depends on the securitization of national borders. Such a changing regime of state intervention is clearly seen at the Iguazú triangle – the tri‐border urban conglomerate that straddles Brazil, Paraguay and Argentina – where the illegality of informal cross‐border trading has been tolerated for decades. Recently stepped up police raids and controls hinder the passage of people and goods, while a new fiscal regime introduced in 2009 in Brazil attempts to regularize cross‐border trafficking by turning petty smugglers into micro entrepreneurs. Petty smugglers – dubbed sacoleiros– can hardly be defined as entrepreneurs and do not constitute an identifiable category of entrepreneurship but, as typical in the informal sector, act on opportunity and need. Drawing on ethnographic research, this paper contextualizes the programmes for border controls and regularizing smuggling inspired by neoliberal ideology in South America. 相似文献
722.
N. KINGO JACOBSEN 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):59-62
Presentation of 3 maps concerning the island of Rømø: Plate 1: The landscape elements (ecotypes). Plate 2: The man-made constructions as settlements, roads, dam, dikes and a harbour as well as plantations. Plate 3: A land use map supplemented by noise zoning of road traffic, an interference leaving a minor part of the area as being untouched nature. Plate 1: 1) Tidal flats, low lying, 2) Creek, 3) Channel, 4) Tidal inlet, 5) Tidal flat, sandy, 6) High sand, 7) Sandy salt marsh, 8) beach ridge, 9) Break-through of the sea, 10) Deflation plain, 11) Dunes, minor forms, 12) Dunes, greater forms, 13) Salt marsh of the foreland, 14) Muddy tidal flats, 15) Phragmites salt marsh, 16) Agricultural area, 17) Polder area, 18) Marine foreland, dike burst. Plate 2: 1) Macadam main road, 2) Macadam road, 3) Gravel road, 4) Earth road, 5) Sand road, 6) Dike, 7) Line of poles, 8) Settlements, 9) Recreational area, 10) Camping, 11) Plantations. Plate 3: 12) Agricultural area, diked in, 13) Agricultural area, undiked. Principles of nature conservancy as well as the future problems of agriculture on the island are discussed. 相似文献
723.
An assessment was made of the mean levels of major and trace elements and of biogenic and organic matter in glacial and river waters within the Aktru river basin (Gornyi Altai, Russia). The analysis showed a general tendency for an increase in mineralization along the direction from the region of alimentation of glaciers to the mouth of the river. A relatively abrupt increase was revealed in Al, Zn, Cu, Pb, Si, NO2 ? and NH4 + concentrations in the source of the Aktru river and its glacial tributaries, with their subsequent decrease downstream. The mechanism for such changes is governed by the conditions of interaction of rocks with meltwaters and river waters. 相似文献
724.
U. Morgenstern R. G. Ditchburn E. G. Vologina M. Sturm 《Journal of Paleolimnology》2013,50(3):345-352
We applied the 32Si dating technique to a sediment core from Lake Baikal to obtain the sediment chronology for the last millennium. The core was recovered about 4 km offshore from the north slope of the South Basin in 1,366 m water depth. The sediment material consisted of continuously accumulated diatom-rich geogenic-terrigenous mud, intercalated with a number of dark olive-grey turbidite layers. The sediment layers containing the turbidites were excluded from 32Si sampling to obtain the chronology that is representative of the continuous sedimentation. The initial 32Si activity of 31.3 dpm kg?1 SiO2, measured in sediment trap samples, confirms the trend of 32Si specific activities of biogenic silica found in other Northern Hemisphere lakes. The four sediment core samples from depth 0–48 cm have 32Si specific activities between 23.5 and 0.5 dpm kg?1 SiO2, with corresponding ages between 60 and 860 years and constant sedimentation rate of 0.036 ± 0.004 cm year?1 over the most recent 800 years. 32Si allowed us for the first time to date the uppermost turbidites in the South Basin of Lake Baikal, to 1030, 1310 and 1670 ad. Given these dates, the last long-distance turbidity current triggered by slope instabilities had occurred 330 years before 2000 ad, and the intervals between the 1310 and 1670 ad event and between the 1030 and 1310 ad event were 360 and 280 years, respectively. The 32Si ages allow unprecedented time resolution for reconstruction of the former environmental and climatic conditions during the past millennium. 相似文献
725.
Following deglaciation, the long-term pattern of change in diatom communities and the inferred history of the aquatic environment are affected by a hierarchy of environmental controls. These include direct climate impacts on a lake’s thermal and hydrologic budgets, as well as the indirect affects of climate on catchment processes, such as weathering, soil development, microbial activity, fire, and vegetation composition and productivity, which affect the transfer of solutes and particulates from the terrestrial ecosystem into the lake. Some of these catchment influences on lacustrine systems operate as time-dependent patterns of primary succession that are set in motion by glacier retreat. This paper provides a conceptual model of some dominant pathways of catchment influence on long-term lake development in glaciated regions and uses a series of paleolimnological examples from arctic, boreal, and temperate regions to evaluate the relative role of direct climate influences and of catchment processes in affecting the trajectory of aquatic ecosystems during the Holocene in different environmental contexts. 相似文献
726.
N. I. Novitskaya 《Geography and Natural Resources》2013,34(1):41-48
Presented are the results from investigating the cenotic structure, structural-dynamical characteristics and spatial differentiation in vegetation of taiga geosystems in the south of the Lena-Katanga plateau of the interfluves between the Lower Tunguska and Nepa rivers. The 1:75 000 map for the present status of vegetation in the key area has been compiled. 相似文献
727.
L. Sedda P.M. Atkinson M.R. Filigheddu G. Cotzia S. Dettori 《International journal of geographical information science》2013,27(7):1083-1096
Cork oak is one of the most valuable natural forest genera in the Mediterranean basin. Modelling cork oak growth has been a challenge for foresters in recent years because of strong site and genetic influences, below-ground competition, management regimes and age effects. Because cork productivity is related to forest height, which is, in turn, related directly with site characteristics, an increase in the accuracy of height prediction implies improved productivity estimation. A Bayesian maximum entropy (BME) geostatistical model was applied to characterize the space–time pattern of height of young cork oak in a forest stand from central Sardinia in the years 2000, 2002, 2003, 2006 and 2008. Cork oak height maps were produced for each of the 5 years. The main goals were to analyse and interpret through time (i) the changes in spatial correlation and (ii) the changes in spatial distribution of cork oak height. The plantation was characterized by an increasing spatial dependence through time, whereas the temporal range was 2 years. Cork oak height was significantly correlated with wind speed (reduced by a neighbouring forest) in all the years implying a single trend. The correlations were larger for 2006 and 2008 than for previous years. Three other environmental variables (shade, elevation and slope) were less significant and their influence restricted to 2 years only. This research has several implications for the management of cork oak in the young phase. 相似文献
728.
Y. Zhang N.A.S. Hamm N. Meratnia A. Stein M. van de Voort P.J.M. Havinga 《International journal of geographical information science》2013,27(8):1373-1392
Wireless sensor network (WSN) applications require efficient, accurate and timely data analysis in order to facilitate (near) real-time critical decision-making and situation awareness. Accurate analysis and decision-making relies on the quality of WSN data as well as on the additional information and context. Raw observations collected from sensor nodes, however, may have low data quality and reliability due to limited WSN resources and harsh deployment environments. This article addresses the quality of WSN data focusing on outlier detection. These are defined as observations that do not conform to the expected behaviour of the data. The developed methodology is based on time-series analysis and geostatistics. Experiments with a real data set from the Swiss Alps showed that the developed methodology accurately detected outliers in WSN data taking advantage of their spatial and temporal correlations. It is concluded that the incorporation of tools for outlier detection in WSNs can be based on current statistical methodology. This provides a usable and important tool in a novel scientific field. 相似文献
729.
Climate change in the Mojave Desert (USA) may result in a greater intensity of summer (monsoon) rain events and greater atmospheric N deposition. Patches of the dominant biological crust moss Syntrichia caninervis were exposed to field treatments of low and high nitrogen supplementation, added summer rain, and combinations thereof, for a period of five years. In the lab, shoots were subjected to a moderate (single rapid-dry treatment) and a severe (double rapid-dry treatment) desiccation stress. Shoots were then hydrated and allowed to regenerate for 6 weeks on sterile sand. Shoots exhibited lower aboveground biomass from the +monsoon treatment, indicating carbon balance deficits under conditions of recurring summer rainfall. The low N treatment and the severe desiccation stress promoted shoot burning (chlorosis) and negatively affected regeneration responses. High N treatment, however, only adversely affected the resumption of apical meristematic growth. Summer irrigation and N application interacted to mitigate the effects of later protonemal emergence time, lower protonemal cover, and lower shoot numbers. Increased monsoonal frequency and higher N deposition as forecast for the northern Mojave Desert may result in declines in shoot biomass and reduced regenerational vigor in S. caninervis. 相似文献
730.
Andy Breckenridge Thomas V. Lowell Timothy G. Fisher Shiyong Yu 《Journal of Paleolimnology》2012,47(3):313-326
The evolution of the early Great Lakes was driven by changing ice sheet geometry, meltwater influx, variable climate, and
isostatic rebound. Unfortunately none of these factors are fully understood. Sediment cores from Fenton Lake and other sites
in the Lake Superior basin have been used to document constantly falling water levels in glacial Lake Minong between 9,000
and 10,600 cal (8.1–9.5 ka) BP. Over three meters of previously unrecovered sediment from Fenton Lake detail a more complex
lake level history than formerly realized, and consists of an early regression, transgression, and final regression. The initial
regression is documented by a transition from gray, clayey silt to black sapropelic silt. The transgression is recorded by
an abrupt return to gray sand and silt, and dates between 9,000 and 9,500 cal (8.1–8.6 ka) BP. The transgression could be
the result of increased discharge from Lake Agassiz overflow or the Laurentide Ice Sheet, and hydraulic damming at the Lake
Minong outlet. Alternatively ice advance in northern Ontario may have blocked an unrecognized low level northern outlet to
glacial Lake Ojibway, which switched Lake Minong overflow back to the Lake Huron basin and raised lake levels. Multiple sites
in the Lake Huron and Michigan basins suggest increased meltwater discharges occurred around the time of the transgression
in Lake Minong, suggesting a possible linkage. The final regression in Fenton Lake is documented by a return to black sapropelic
silt, which coincides with varve cessation in the Superior basin when Lake Agassiz overflow and glacial meltwater was diverted
to glacial Lake Ojibway in northern Ontario. 相似文献