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101.
Laura Pereira 《Singapore journal of tropical geography》2010,31(3):384-400
Coca is a controversial plant, existing on the boundary between legality and illegality. This study aims at providing an analytical technique for discussing the problematic of coca in Colombia. Using new theoretical propositions in human geography, a more‐than‐human approach is adopted to encounter coca holistically. The results are a narrative account of coca's social life as experienced by the researcher following its network of non‐cocaine derivatives. An analytical section invokes the Foucauldian dispositif to the drug trade and utilizes concepts of informed materials and technological zones to describe coca outside a political economy discourse. The research finds that coca's dynamic materiality complicates it as a commodity and that these conventional approaches do not fully encapsulate this complexity. By grappling with the messiness of coca's materiality, this paper reveals the multiplicity and interplay of coca's definitions, which lie at the heart of many conflicts. 相似文献
102.
Hydrologic,geomorphic and climatic processes controlling willow establishment in a montane ecosystem
David J. Cooper Joyce Dickens N. Thompson Hobbs Lindsey Christensen Laura Landrum 《水文研究》2006,20(8):1845-1864
Willow communities dominate mid‐elevation riparian areas throughout the Rocky Mountains of North America. However, many willow stands are rapidly declining in aerial cover and individual plants in stature. A poor understanding of the processes that control willow establishment hinders identifying the causes of this decline. We analysed the processes that have facilitated or limited willow establishment over the last half of the 20th century on two large floodplains in Rocky Mountain National Park in Colorado by addressing two questions: (1) How does hydrologic regime control willow establishment on different fluvial landforms? (2) How might climate‐driven variations in hydrologic regime affect future willow establishment? We precisely aged willows on the three most common fluvial landforms, stream point bars, drained beaver ponds, and abandoned channels, and statistically related establishment dates to patterns of annual stream peak flow. The role of peak flow on willow establishment varied significantly by landform. Willow recruitment had occurred nearly every year on point bars. In former beaver complexes, most willows had established following dam breaches, whereas willows had established on abandoned channels for several years following channel avulsion. Establishment on point bars and abandoned channels was driven by peak flows of 2‐ to 5‐year return intervals, whereas in abandoned beaver ponds most establishment was associated with flow events of >5‐year return interval. Models of climate change suggest that temperatures will increase and precipitation seasonality will shift over the coming decades in the Rocky Mountains, leading to earlier spring runoff, lower summer and fall flows, decreased snowpack and decreased soil moisture. Such changes are likely to diminish opportunities for willow establishment. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Jesper Sommer-Larsen Sune Toft Jesper Rasmussen Kristian Pedersen Martin Götz Laura Portinari 《Astrophysics and Space Science》2003,284(2):693-696
The X-ray properties of the haloes of disk galaxies formed in fully cosmological, hydro/gravity simulations are discussed.
The results are found to be consistent with observational X-ray detections and upper limits. Disk galaxy haloes are predicted
to be about an order of magnitude brighter at z ∼ 1 than at z=0. The Lyα and Hα surface brightness of an edge-on, Milky Way like model galaxy has been determined. The emission is found
to be quite extended, with a scale height of about 600 pc, neglecting dust corrections.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Amado LL Robaldo RB Geracitano L Monserrat JM Bianchini A 《Marine pollution bulletin》2006,52(2):207-213
Biomarkers of exposure (liver metallothionein-like proteins content and catalase and glutathione S-transferase activities) and effect (liver lipoperoxidation and blood cell DNA damage) of contaminants were analyzed in the Brazilian flounder Paralichthys orbignyanus from the Patos Lagoon estuary (Southern Brazil). Flounders were collected for a year in two sites: "Coroa do Boi" (polluted site) and "Saco do Justino" (non-polluted site). Results indicated that micronucleated cells frequency was the best biomarker to distinguish flounders from the two sites. Taken together, data from DNA damage analyses (micronucleus test and comet assay) indicated that flounders from the non-polluted site efficiently repaired the DNA breaks, contrary to those from the polluted site, which probably had their DNA repair system inhibited or exhausted. Furthermore, data from enzyme activities (catalase and GST) and lipid peroxidation indicated that flounders from the polluted site were under oxidative stress in summer and autumn. 相似文献
110.
New Zealand fur seals in the Kaikoura region breed near a town with expanding tourist and fishing industries and commonly come ashore entangled in nets and plastic debris. However, the rate at which entanglement occurs was previously unknown. A decade of Department of Conservation seal callout data was analysed to determine the level of entanglement in the region and the most common debris type. Monitoring of adult female fur seals released from entanglement provided information on the potential for serious wounds to heal and survivorship of released individuals. Entanglement rates of pinnipeds in Kaikoura are some of the highest reported world-wide (average range: 0.6-2.8%) with green trawl net (42%), and plastic strapping tape (31%) together contributing the most to debris types. Nearly half of the reported entangled seals are successfully released (43%) and post-release monitoring shows that with appropriate intervention the chance of an individual surviving even with a significant entanglement wound is high. Our study demonstrates that while entanglement in the region is high, a successful intervention protocol may help reduce the potential for entanglement-related mortality in the region. 相似文献