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211.
ABSTRACT Operational cloud seeding projects, those designed to produce a desired change in the weather and that are nonexperimental in nature, continue to be pursued widely in the United States. A recurring question by scientists, project sponsors, and cloud seeders has been, “was the weather altered and if so, by how much?” Evaluation of such projects is now recognized as having scientific benefits, and a four-year study has addressed various techniques and statistical methods to perform evaluations and to learn more about how to modify the weather. Most such evaluations hinge on some type of space-time comparisons, but valid comparisons can be obtained only avoiding biases in the project design and operation. Through simulated changes in weather conditions, it was determined that the principal component regression techniques were used to evaluate selected rain and hail modification projects, revealing modification in certain projects and none in others. Various relevant issues have been examined such as use of other weather variables (covariates) to increase detection power, the validity of using historical data as controls for discrete operational periods, possible randomization options during cloud seeding operations, and analyses of individual rain events versus that based on monthly or seasonal units. 相似文献
212.
Canchao Yang Longwu Wang Shun-Jen Cheng Yu-Cheng Hsu Wei Liang Anders Pape Møller 《Die Naturwissenschaften》2014,101(9):727-734
Parasites may, in multi-parasite systems, block the defenses of their hosts and thus thwart host recognition of parasites by frequency-dependent selection. Nest defenses as frontline may block or promote the subsequent stage of defenses such as egg recognition. We conducted comparative studies of the defensive strategies of a host of the Oriental cuckoo Cuculus optatus, the yellow-bellied prinia Prinia flaviventris, in mainland China with multiple species of cuckoos and in Taiwan with a single cuckoo species. Cuckoo hosts did not exhibit aggression toward cuckoos in the presence of multiple cuckoo species but showed strong aggressive defenses of hosts directed toward cuckoos in Taiwan. Furthermore, the cuckoo host in populations with a single cuckoo species was able to distinguish adults of its brood parasite, the Oriental cuckoo, from adult common cuckoos (Cuculus canorus). This represents the first case in which a cuckoo host has been shown to specifically distinguish Oriental cuckoo, from other Cuculus species. Hosts ejected eggs at a higher rate in a single cuckoo species system than in a multi-species cuckoo system, which supports the strategy facilitation hypothesis. Granularity analysis of variation in egg phenotype based on avian vision modeling supported the egg signature hypothesis in hosts because Taiwanese prinias increased consistency in the appearance of their eggs within individual hosts thus favoring efficient discrimination against cuckoo eggs. This study significantly improves our knowledge of intraspecific variation in antiparasitism behavior of hosts between single- and multi-cuckoo systems. 相似文献
213.
Edward Saja Sanneh Allen H. Hu Chia-Wei Hsu Momodou Njie 《Mitigation and Adaptation Strategies for Global Change》2014,19(8):1163-1178
Adaptation to climate change has been recognized as very important in developing countries that face the greatest threats from global warming. In proposing various adaptation approaches, the United Nations Intergovernmental Panel on Climate Change required nations to prepare adaptation plans of action. However, the areas of priority in climate change adaptation have not been considered. This study has developed a new prioritization methodology for climate change adaptation in developing countries. Five categories and 25 approaches in climate change adaptation were adopted through a thorough and detailed analysis of pertinent literature related to the National Adaptation Program of Action (NAPA) in the Gambia. A fuzzy analytic hierarchy process-based questionnaire survey was designed and presented to 12 experts chosen from the committee members of the Gambia’s NAPA. The survey was made to determine the relative importance of the strategies for climate change adaptation. The results indicate that the five most important adaptation categories are health (0.223), forestry (0.213), water (0.210), food (0.181), and energy (0.174), with health as the number one priority in climate change adaptation. Further findings show that the prioritization order of the adaptation approaches to climate change in the Gambia is as follows: “Health education,” “public sensitization,” “water supply infrastructure development,” “microfinance,” and “infrastructure and technology enhancement.” 相似文献