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Local geography and gender are two major factors determining which crop varieties are cultivated in a case study of two rural villages in Bangladesh. This paper explores the interrelationships between gender, agrobiodiversity, and the use of, and preferences for, improved and local crop varieties. These are examined in relation to rice, minor field crops, and home garden fruits and vegetables. Reasons for both the displacement and the persistence of local varieties (LVs) are analysed in comparison to improved variety (IV) diffusion. The research evaluates agrobiodiversity through the number, types, and varieties of crops grown in fields and home gardens. The desired agroecological, economic, and cultural characteristics of crops grown document how respondents rank their variety preferences. Variety preferences and the perceived importance of LV preservation are compared with what is actually grown. The study indicates that there was little variation between villages in their approach towards the use of IV and LV rice; IVs were cultivated for their high yields and LV rice for taste and culinary uses. However, there were significant differences in relative agricultural dependence between the two villages which led to unique variety preferences. In both villages, women's preferences for IVs or LVs play a major role in crop choices, particularly as they manifest themselves in gendered domains of authority. 相似文献
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U-series Isotope Data on Lau Basin Glasses: the Role of Subduction-related Fluids during Melt Generation in Back-arc Basins 总被引：6，自引：2，他引：6
PEATE DAVID W.; KOKFELT THOMAS F.; HAWKESWORTH CHRIS J.; VAN CALSTEREN PETER W.; HERGT JANET M.; PEARCE JULIAN A. 《Journal of Petrology》2001,42(8):1449-1470
New thermal ionization mass spectrometry U-series disequilibriumdata are presented for 24 basaltic to dacitic glasses from activespreading centres in the back-arc Lau Basin (SW Pacific), togetherwith additional inductively coupled plasma mass spectrometrytrace element analyses and Sr–Nd–Pb isotope data.Valu Fa Ridge samples, adjacent to the arc front, have highU/Th and (230Th/238U) <1, implying a recent (<<350ka) addition of a U-rich slab-derived fluid. The Valu Fa datacan be combined with existing 230Th–238U data for theCentral Tonga arc to infer a fluid addition event at 相似文献
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The Bathurst barren-ground caribou herd was chosen as the focus of a study of the possible effects of a changed climate on hunting of a caribou herd in the Northwest Territories. Four climate change scenarios representing conditions under a doubling of atmospheric carbon dioxide concentrations were used in the study. The locations of the Bathurst herd throughout the year were determined, and the 1951 to 1980 average monthly temperatures and total monthly precipitation amounts were ascertained at those locations. The four climate change scenarios were applied, with changes in average monthly temperatures and in total monthly precipitation amounts noted. Analyses indicate a possible increase in winter snowfall, and increased insect harassment of caribou in the summer, due to an increase in average monthly temperatures. The reduced accessibility and health of caribou in the Bathurst herd suggest a reduced hunting potential. Management options are briefly discussed. 相似文献
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The paper deals with sedimentary structures in shallow-water Precambrian deposits of Lower Torridonian age in the island of Skye in northwestern Scotland. The structures described include irregular lamination, ripple bedding, festoon bedding and structures produced by local erosion and reworking. Evidence of penecontemporaneous disturbance thought to be due to the movements of quicksands is briefly referred to. Variations in lithology and structure within the succession are attributed to local differences in conditions within a possible environment of sedimentation in an intertidal zone with off-shore sandbanks. 相似文献
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MARTIN ROSS JANET E. CAMPBELL MICHEL PARENT ROBERTA S. ADAMS 《Boreas: An International Journal of Quaternary Research》2009,38(3):421-439
The analysis of the glacial landscape of southern Saskatchewan (Canada) through multiple data sets (e.g. digital elevation model, till compositional data) has revealed previously unrecognized subglacial sediment–landform assemblages. A southwest-trending corridor of mega-scale till lineations (Maskwa corridor) bounded on each side by hummocky terrain extends from the Canadian Shield to southwestern Saskatchewan. This landform assemblage is clearly cross-cut by a broad south to southeast trending corridor (Buffalo corridor) consisting of subparallel curvilinear till ridges. The carbonate content of the surface till is spatially consistent within these assemblages, suggesting a strong sediment–landform relationship. The two corridors are interpreted as the product of palaeo-ice streams. The Maskwa palaeo-ice stream flowed up the regional slope and across preglacial valleys, indicating it was thick and stable. Narrow dispersal trains extending across as well as down-glacier from the Athabasca Basin suggest that the Maskwa palaeo-ice stream extended far into the ice sheet across contrasting shield and platform terrains. In comparison, the Buffalo palaeo-ice stream was thinner and largely controlled by subglacial geology and topography. Its catchments were located at the Canadian Shield boundary and the system was oriented along-slope. It experienced lateral shifts and it was fed by a network of tributaries. The glacial dynamics shift from the Maskwa to the Buffalo system occurred at about 13.5 14 C kyr BP. The Buffalo system later evolved into thin outlet lobes until final deglaciation of the area. The proposed model has implications for ice-sheet reconstruction and the assessment of till properties in the prairies and in similar terrains. 相似文献
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It is known that the maximum danger of flutter-type aerodynamic instability for suspension bridges occurs during the early erection phases of the deck. The effectiveness of two different provisional measures for increasing the instability critical windspeed in such conditions is evaluated for a long span suspension bridge with flat box stiffening girder. 相似文献
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Focus groups conducted in two urban areas in New Zealand explored perceptions of natural hazards and disaster preparedness. The groups were structured by socio-economic status, gender, age, and cultural background. Participants were generally aware of likely major hazard events but few maintained emergency kits or had prepared emergency plans. People held an optimistic attitude, believing they could cope with disaster. Differences amongst the groups included the inability of lower socio-economic groups to afford emergency kits or insurance and evidence of strong supportive networking among Maori and Samoan groups. 相似文献
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