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Penelope Ploughman 《Disasters》1997,21(2):118-137
The starting-point of this paper is the assumption that credibility and the right to be heard are differentially distributed in any social system and therefore a 'hierarchy of credibility' exists. To test this, the media coverage of the Love Canal, New York, hazardous waste landfill disaster and six other disasters was examined to determine if this hierarchy exists in all cases. A hierarchy of credibility emphasising the views of established news sources with routine and habitual access to the media was demonstrated in the majority of events examined. However, the Love Canal disaster was one of two where this hierarchy was disrupted due to a number of factors. These included the contentious or political nature of the event, its duration, the extent of competition for credibility and coverage among news sources, the extent of information shortage, the type of news medium, the degree of sympathetic and representational salience of victims and the extent to which they organised and achieved status as 'newsmakers'. Building on disaster research, a model of the operation of the credibility hierarchy in coverage of disasters is presented and discussed. 相似文献
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Penelope Hansen 《环境质量管理》2001,11(2):15-28
The Environmental Technology Verification Program (ETV) was started by the U.S. Environmental Protection Agency in October 1995 to generate independent and credible data on the performance of innovative technologies that have the potential to improve protection of public health and the environment. The purpose of this program is to help organizations, industries, businesses, states, communities, and individuals make better‐informed decisions when selecting new environmental technologies. The program has now been in existence for six years and the following article presents, for the first time, the results achieved to date and the program's future operating plans. © 2001 John Wiley & Sons, Inc. 相似文献
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Simple molecular method to distinguish the identity of Calanus species (Copepoda: Calanoida) at any developmental stage 总被引:1,自引:0,他引:1
Diagnostic morphological characteristics of copepods of the genus Calanus are restricted largely to minor variations in secondary sex characteristics. This presents a persistent problem in the identification
of individuals to species level, especially for immature stages. We have developed a simple molecular technique to distinguish
between the North Atlantic Calanus species (C. helgolandicus, C. finmarchicus, C. glacialis and C. hyperboreus) at any life stage. Using the polymerase chain-reaction (PCR), the mitochodrial large subunit (16S) ribosomal RNA (rRNA)
gene was amplified from individual copepods preserved in ethanol. Subsequent digestion of the amplified products with the
restriction enzymes DdeI and VspI, followed by electrophoretic separation in 2% agarose (Metaphor, FMC Ltd), produced a characteristic pattern for each species.
The versatility of the method is demonstrated by the unambiguous identification to species of any life stage, from egg to
adult, and of individual body parts.
Received: 11 May 1998 / Accepted: 5 August 1998 相似文献
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Acartia and Paracartia species, often known to co-occur, can exhibit complex life cycles, including the production of resting eggs. Studying and understanding their population dynamics is hindered by the inability to identify eggs and early developmental stages using morphological techniques. We have developed a simple molecular technique to distinguish between the three species of the Acartiidae family (Acartia clausi, A. discaudata and Paracartia grani) that co-occur in the Thau lagoon (43°25′N; 03°40′E) in southern France. Direct amplification of a partial region of the mitochondrial cytochrome oxidase I gene by polymerase chain reaction and subsequent restriction fragment length polymorphism results in a unique restriction profile for each species. The technique is capable of determining the identity of individual eggs, including resting eggs retrieved from sediment samples, illustrating its application in facilitating population dynamic studies of this ubiquitous and important member of the zooplankton community. 相似文献
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B.?W.?HansenEmail author T.?Marker P.?Andreassen E.?Arashkewich F.?Carlotti P.?Lindeque K.?S.?Tande M.?Wagner 《Marine Biology》2003,142(5):877-893
Two different Calanus finmarchicus (Gunnerus) cohorts originating from 60°N (Bergen) and 69°N (Tromsø) were investigated in equal environmental conditions to study their different physiological responses to the same environment. A two-plus-two-bag mesocosm study was carried out between March and July 1998, in Håkøybotn, Tromsø, in order to determine development and mortality rates of the two parallel cohorts of C. finmarchicus. For practical reasons, the cohort from Bergen was incubated 10 days earlier than the Tromsø cohort. Consequently, they were exposed to elevated food conditions as compared to the Tromsø cohort. A high initial mortality among the Bergen cohort could clearly be ascribed, by genetic discrimination, to "contamination" with C. helgolandicus. After this initial mass mortality, the mortality was constantly 0.03-0.04 dayу. In cohorts starting from naupliar stage I, there was no significant difference in development or growth, the median development time (NI-CIV) differing by only 7 days (~6%). The difference in development time can be explained to a large extent (~4 days) by temperature differences. This is substantiated with model simulations using a physiological model developed for C. finmarchicus. There was a time lag in incubation between the two cohorts, resulting in elevated temperature during incubation of the Tromsø cohort. A fraction of both cohorts differentiated sexually at stage CV, with males differentiating before females. Females from both cohorts produced eggs, but specific egg production differed significantly (P>0.001, t-test). This was supported by elevated RNA:DNA ratio in females from the Bergen cohort. Both cohorts demonstrated quite similar development and physiological growth rates and, consequently, are considered to belong to the same genetic population inhabiting the Norwegian Shelf. The study demonstrates that C. finmarchicus is capable of adaptation to changes in environment and, thereby, demonstrates a significant physiological plasticity. 相似文献
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Continental Australia and Tasmania cover a wide range of latitudes from tropical regions in the north through the arid and semi-arid core to cool temperature regions further south. Vegetation is equally varied and because of this and the continent's isolation during the Tertiary, floral and faunal diversity and endemism are very high. Europeans arrived 200 years ago and since that time have markedly modified the landscape by clearing and changing the vegetation, predominantly for agricultural and urban development. Both accidental and deliberate introductions of stock, weeds, crops, trees and pasture plants have also caused enormous changes to Australian environments. In the last few years the deleterious effects of some of these changes have been relaised, for example the extent of soil degradation. Measures are being taken to rectify problems and techniques are being introduced which benefit both primary producers and other users of the land and also nature conservation. Some of these measures for a more sustainable use of the land are illustrated here for four vegetation types, eucalypt woodland, native forests, grasslands and arid systems. They include adopting native tree species for timber production and native grasses for pasture, retention of native vegetation and paying attention to conservation of invertebrates in Parks and Reserves. 相似文献
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Mutualistic Benefits Generate an Unequal Distribution of Risky Activities Among Unrelated Group Members 总被引:1,自引:0,他引:1
Recent studies provide a new challenge to the adequacy of theories concerning the evolution of cooperation among nonrelatives:
some individuals perform high-risk activities while others do not. We examined a communal hymenopteran species, Lasioglossum
(Chilalictus)
hemichalceum, to determine why group members engaged in demonstrably risky activities (foraging) tolerate the selfish behavior (remaining
in the nest) of unrelated nestmates. Experimental removal of adult females indicated that their presence is required for the
protection of brood from ant predators. Nonforagers ensure the continued presence of adults in the nest if the risk-taking
foragers die, thereby safeguarding the survival of forager offspring. This results in an unequal distribution of risky activities
within social groups in which avoidance of risky activities by some group members is ultimately beneficial to risk takers.
Received: 10 June 1997 / Accepted in revised form: 25 May 1998 相似文献