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11.
12.
Angie Carter 《社会与自然资源》2019,32(8):893-910
Women own or co-own approximately half of the farmland in Iowa, United States, yet researchers are only beginning to study these landowners’ social relationships in relation to their land. This study analyzes qualitative data collected in Iowa through a series of meetings hosted by the Women, Food and Agriculture Network (WFAN). I find that social control through exclusion constrains women landowners’ access to information about and implementation of conservation. Specifically, I identify how women landowners experience the social processes of boundary maintenance and othering in land management. These processes create barriers to conservation adoption and maintain gendered agricultural landscapes. The women who participated in WFAN’s conservation programs express their experience of and resistance to dominant narratives as they attempt to create landscape change. These findings highlight the importance of further study of inequality processes and their relation to control of farmland if conservation goals are to be met. 相似文献
13.
G. Robbert Biesbroek Rob J. Swart Timothy R. Carter Caroline Cowan Thomas Henrichs Hanna Mela Michael D. Morecroft Daniela Rey 《Global Environmental Change》2010,20(3):440-450
For the last two decades, European climate policy has focused almost exclusively on mitigation of climate change. It was only well after the turn of the century, with impacts of climate change increasingly being observed, that adaptation was added to the policy agenda and EU Member States started to develop National Adaptation Strategies (NASs). This paper reviews seven National Adaptation Strategies that were either formally adopted or under development by Member States at the end of 2008. The strategies are analysed under the following six themes. Firstly, the factors motivating and facilitating the development of a national adaptation strategy. Secondly, the scientific and technical support needed for the development and implementation of such a strategy. Thirdly, the role of the strategy in information, communication and awareness-raising of the adaptation issue. Fourthly, new or existing forms of multi-level governance to implement the proposed actions. Fifthly, how the strategy addresses integration and coordination with other policy domains. Finally, how the strategy suggests the implementation and how the strategy is evaluated. The paper notes that the role of National Adaptation Strategies in the wider governance of adaptation differs between countries but clearly benchmarks a new political commitment to adaptation at national policy levels. However, we also find that in most cases approaches for implementing and evaluating the strategies are yet to be defined. The paper concludes that even though the strategies show great resemblance in terms of topics, methods and approaches, there are many institutional challenges, including multi-level governance and policy integration issues, which can act as considerable barriers in future policy implementation. 相似文献
14.
An assessment of the effects of climatic change on agriculture 总被引:3,自引:0,他引:3
This paper summarizes some of the results and conclusions of an international project funded by IIASA and UNEP on the effects of climatic variations on agriculture. An overall goal of the project was to improve our understanding both of first-order effects of climatic variations on agricultural productivity and of higher-order effects on regional and national economies. Two broad types of experiments are described: (i) impact experiments, which provide estimates of first-order and higher-order effects of climatic variations on farming systems, and which assume that no adjustments are put in place, and (ii) adjustment experiments, which evaluate a number of adjustments available at the farm or government level to offset or mitigate these effects.The results from case studies in cool temperate and cold regions in Saskatchewan (Canada), Iceland, Finland, northern European U.S.S.R. and Japan] are described here. Findings from a parallel set of IIASA/UNEP case studies in semiarid regions, which examine the effects of a different set of climatic scenarios, are reported elsewhere (Parry et al., 1988b). 相似文献
15.
A daily surface soil moisture model described and tested previously with data from the Phoenix, AR (USA) area, has been applied now to climate data collected in semi-arid Botswana over a multi-year period. The physically based model was calibrated with observed surface moisture data from one growing season and validated with data from another. Good overall agreement (r2 = .89) was found between the observed and modelled data. The seasonal variability of precipitation in this region is reflected in the simulated daily surface moisture. The response of the natural savanna vegetation as observed from monthly composites of satellite-derived Normalized Difference Vegetation Index (NDVI) is also monitored for the same period. It is seen that the NDVI peaks at different times during the rainy season from one year to the next, according not only to the total seasonal precipitation, but its temporal distribution as well. It is also seen that there is a delay in intraseasonal vegetation response. While the NDVI is poorly correlated with the current month's average soil moisture, a distinct relationship with the previous month's average soil moisture was found. 相似文献
16.
R.W.G. Carter 《Sedimentary Geology》1982,33(1):35-56
Mixes of carbonate and quartz sands, which are commonly encountered in Recent coastal sediments, require careful analysis if they are to be correctly interpreted. Grain-size data fall into multimodal or segmented zig-zag distributions which may require some kind of component separation if they are to be summarised by conventional statistics, and before they can be assigned to a particular hydrodynamic depositional process or environment. Unfortunately, separation techniques are only spasmodically applied, usually without due regard to the consequences. Such artificially filtered or truncated distributions are of little subsequent use. Using a range of samples from two beaches in NW Ireland, where carbonate proportions range from nearly zero to over sixty percent, the interrelationships of the two dominant components were examined. Where only a small carbonate proportion is incorporated into a large quartz one, predictable modifications of the size-curve are apparent. However, the components are more independent if mixtures are near equal. The occurrence of a number of distinctive combinations of simple straight lines and complex zig-zag curves probably reflects the relatively dynamic nature of the carbonate fraction. 相似文献
17.
18.
Adam Carter Benjamin van Wyk de Vries Karim Kelfoun Patrick Bachèlery Pierre Briole 《Bulletin of Volcanology》2007,69(7):741-756
A clear model of structures and associated stress fields of a volcano can provide a framework in which to study and monitor
activity. We propose a volcano-tectonic model for the dynamics of the summit of Piton de la Fournaise (La Reunion Island,
Indian Ocean). The summit contains two main pit crater structures (Dolomieu and Bory), two active rift zones, and a slumping
eastern sector, all of which contribute to the actual fracture system. Dolomieu has developed over 100 years by sudden large
collapse events and subsequent smaller drops that include terrace formation. Small intra-pit collapse scars and eruptive fissures
are located along the southern floor of Dolomieu. The western pit wall of Dolomieu has a superficial inward dipping normal
fault boundary connected to a deeper ring fault system. Outside Dolomieu, an oval extension zone containing sub-parallel pit-related
fractures extends to a maximum distance of 225 m from the pit. At the summit the main trend for eruptive fissures is N80°,
normal to the north–south rift zone. The terraced structure of Dolomieu has been reproduced by analogue models with a roof
to width ratio of approximately 1, suggesting an original magma chamber depth of about 1 km. Such a chamber may continue to
act as a storage location today. The east flank has a convex–concave profile and is bounded by strike-slip fractures that
define a gravity slump. This zone is bound to the north by strike-slip fractures that may delineate a shear zone. The southern
reciprocal shear zone is probably marked by an alignment of large scoria cones and is hidden by recent aa lavas. The slump
head intersects Dolomieu pit and may slide on a hydrothermally altered layer known to be located at a depth of around 300 m.
Our model has the summit activity controlled by the pit crater collapse structure, not the rifts. The rifts become important
on the mid-flanks of the cone, away from pit-related fractures. On the east flank the superficial structures are controlled
by the slump. We suggest that during pit subsidence intra-pit eruptions may occur. During tumescence, however, the pit system
may become blocked and a flank eruption is more likely. Intrusions along the rift may cause deformation that subsequently
increases the slump’s potential to deform. Conversely, slumping may influence the east flank stress distribution and locally
control intrusion direction. These predictions can be tested with monitoring data to validate the model and, eventually, improve
monitoring. 相似文献
19.
Although the field of view of the Normal Incidence Spectrometer (NIS) of the Coronal Diagnostic Spectrometer (CDS) is 4×4 arc min, it is possible to observe the full solar disk by forming a mosaic of images taken in succession. This paper describes just such a study which has been used to collect images of the Sun simultaneously in six wavelengths between 304 Ú and 630 Ú, and with a temperature coverage between 5×104 K and 2.5×106 K. A representative sample of the resulting images is presented. These data can be used to explore the origin of solar EUV variability, and examine large-scale solar features. Another use of these data is to calibrate the pointing of the CDS Offset Pointing System (OPS), by comparing them against the SOHO Extreme ultraviolet Imaging Telescope (EIT) full-disk images taken at the same time. Many joint observations are made with CDS and other SOHO instruments, and calibration of the pointing is crucial to the co-pointing of the instruments, and to the analyses of these data. Coalignment is done by fitting to a cross-correlation function, using an IDL procedure which can be applied to any CDS/NIS data set. The accuracy of an individual coalignment can be demonstrated to be in the range 1–2 arc sec. The overall accuracy of the OPS calibration is ±5 arc sec, mainly attributable to measurement error in the actuator positions. An onboard Spartan Intermediate Sun Sensor of the Lockheed design, which was intended to provide greater pointing accuracy, exhibits a time-varying calibration, possibly due to a gradual loss of sensitivity. 相似文献
20.
Transient creep and semibrittle behavior of crystalline rocks 总被引:1,自引:0,他引:1
We review transient creep and semibrittle behavior of crystalline solids. The results are expected to be pertinent to crystalline rocks undergoing deformation in the depth range 5 to 20 km, corresponding to depths of focus of many major earthquakes. Transient creep data for crystalline rocks at elevated temperatures are analyzed but are poorly understood because of lack of information on the deformation processes which, at low to moderate pressure, are likely to be semibrittle in nature. Activation energies for transient creep at high effective confining pressure are much higher than those found for atmospheric pressure tests in which thermally-activated microfracturing probably dominates the creep rate. Empirical transient creep equations are extrapolated at 200° to 600°C, stresses from 0.1 to 1.0 kbar, to times ranging from 3.17×102 to 3.17×108 years. At the higher temperatures, appreciable transient creep strains may take place but the physical significance of the results is in question because the flow mechanisms have not been determined. The purpose of this paper is to stimulate careful research on this important topic. 相似文献