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91.
Using a sample of 232 MBA alumni, we tested the impact of respondent age, gender, and their interaction on career progress outcomes (managerial level, number of promotions, and salary) and whether age‐ and gender‐type of contexts moderated these relationships. Women's salaries did not increase much with age, whereas men's salaries showed a marked increase with age. We also found a gender × job gender‐type effect on salary, such that women earned somewhat higher salaries in masculine‐typed jobs, while men earned considerably higher salaries in feminine‐typed jobs. In addition, we observed a three‐way interaction between gender, age, and age‐type of industry indicating that younger men received more promotions in old‐typed industries, while younger women received more promotions in young‐typed ones. Results are discussed in light of cognitive matching approaches and status characteristics theory. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
92.
Long-term signal evolution is shaped by a variety of selective pressures including the need to convey additional information or to improve message transfer to specific receivers or through multiple environments. Here, we test the relative importance of information and sensory modality in shaping the long-term evolution of multimodal signals in Sceloporus lizards. To broadcast identity at territorial boundaries, male Sceloporus use both visual motion (headbob) and chemical signals, whereas they use color (blue belly patches) to signal aggression. Using modern phylogenetic comparative methods, we found a negative correlation between evolutionary changes in visual motion (headbobs) and chemical (femoral pore) signals, but only indirect ties between the evolution of color and motion signals (both of which are perceived visually) through viviparity, and no evidence of an evolutionary link between color and chemical signals. We also find a negative correlation between arboreality and chemical signals. Thus, information content (in this case, broadcasting individual identity versus signaling aggression) appears to play a more important role than sensory modality or physical distance in guiding long-term signal evolution. Additional insights into the underlying evolutionary processes are described, illustrating the utility of a phylogenetic approach.  相似文献   
93.
In this paper we explore the concept of ‘natural disasters’ as opportunities for influencing public perceptions of the environment through the media. We provide a critical analysis of the discourse in a selection of newspaper articles and identify the way in which various actors have utilised UK national newspaper coverage of the Asian tsunami to promote particular agendas and to legitimise policies and actions. A systematic and iterative sampling approach was developed that allowed us to combine quantitative and qualitative methods to search for articles that contained content directly related to the environmental aspects of the tsunami. Three main themes emerged; coastal ecosystems, the fisheries sector, and redevelopment. The discourse within these areas was markedly different. While the coastal ecosystems discourse was hegemonic in terms of narratives and actor coalitions, the fisheries and redevelopment discourse incorporated a more diverse set of actors and storylines that perhaps reflects the lack of consensus on the best way of achieving sustainable solutions. We also contrast the limited discussion and representation of tsunami-related environmental issues within UK national newspapers with the more detailed discussion within the peer-reviewed literature and the grey literature. We argue that ‘natural disasters’ provide both opportunities and risks for raising awareness of environmental issues, mobilising funding and directing action to environmentally and socially vulnerable areas of the world, and that consequently NGOs, intergovernmental bodies and government departments should be mindful of the long-term consequences of global media attention.  相似文献   
94.
This paper presents a unique data set of lead, arsenic, polychlorinated biphenyl (PCB), and polycyclic aromatic hydrocarbon (PAH) concentrations in soil samples collected from the metropolitan New York City area in the aftermath of Hurricane Sandy. Initial samples were collected by citizen scientists recruited via social media, a relatively unusual approach for a sample collection project. Participants in the affected areas collected 63 usable samples from basements, gardens, roads, and beaches. Results indicate high levels of arsenic, lead, PCBs, and PAHs in an area approximately 800 feet south of the United States Environmental Protection Agency (US EPA) Superfund site at Newtown Creek. A location adjacent to the Gowanus Canal, another Superfund site, was found to have high PCB concentrations. Areas of high PAH contamination tended to be near high traffic areas or next to sites of known contamination. While contamination as a direct result of Hurricane Sandy cannot be demonstrated conclusively, the presence of high levels of contamination close to known contamination sites, evidence for co-contamination, and decrease in number of samples containing measureable amounts of semi-volatile compounds from samples collected at similar locations 9 months after the storm suggest that contaminated particles may have migrated to residential areas as a result of flooding.  相似文献   
95.
96.
Linking Ecological Sustainability and World Food Needs   总被引:1,自引:0,他引:1  
Ecological approaches to agriculture can provide useful guidelines for addressing world food needs, while avoiding adverse environmental and social impacts. Experiments in both natural and agricultural ecosystems suggest that systems with high plant diversity may be more productive, more stable and more resilient than species-poor systems. In addition, systems with high plant diversity support higher levels of biodiversity in other functional groups, which may enhance the productivity of the plant component. Given these benefits of diverse systems, various approaches for converting conventional high input agricultural systems to more sustainable systems are addressed. Andow and Hidaka's (1989) concept of production syndromes is considered in the context of conversion to sustainable agriculture.  相似文献   
97.
In this paper we explore the concept of ‘natural disasters’ as opportunities for influencing public perceptions of the environment through the media. We provide a critical analysis of the discourse in a selection of newspaper articles and identify the way in which various actors have utilised UK national newspaper coverage of the Asian tsunami to promote particular agendas and to legitimise policies and actions. A systematic and iterative sampling approach was developed that allowed us to combine quantitative and qualitative methods to search for articles that contained content directly related to the environmental aspects of the tsunami. Three main themes emerged; coastal ecosystems, the fisheries sector, and redevelopment. The discourse within these areas was markedly different. While the coastal ecosystems discourse was hegemonic in terms of narratives and actor coalitions, the fisheries and redevelopment discourse incorporated a more diverse set of actors and storylines that perhaps reflects the lack of consensus on the best way of achieving sustainable solutions. We also contrast the limited discussion and representation of tsunami-related environmental issues within UK national newspapers with the more detailed discussion within the peer-reviewed literature and the grey literature. We argue that ‘natural disasters’ provide both opportunities and risks for raising awareness of environmental issues, mobilising funding and directing action to environmentally and socially vulnerable areas of the world, and that consequently NGOs, intergovernmental bodies and government departments should be mindful of the long-term consequences of global media attention.  相似文献   
98.
Polyphenols in plants can protect proteins from degradation and improve the efficiency of conversion of plant protein to animal protein (meat and milk), but can this be achieved in a way that is environmentally sustainable, profitable to the livestock farmer and is consistent with aspirations for improved livestock nutrition, health, welfare and product quality? Given that grazed and conserved forage is the bedrock of sustainable ruminant production, this paper attempts to consider what challenges are ahead in terms of enhancing productive efficiency, reducing the polluting footprint of livestock agriculture and alleviating the endemic parasitism that occurs with grazing animals.  相似文献   
99.
A key question facing conservation biologists is whether declines in species' distributions are keeping pace with landscape change, or whether current distributions overestimate probabilities of future persistence. We use metapopulations of the marsh fritillary butterfly Euphydryas aurinia in the United Kingdom as a model system to test for extinction debt in a declining species. We derive parameters for a metapopulation model (incidence function model, IFM) using information from a 625-km2 landscape where habitat patch occupancy, colonization, and extinction rates for E. aurinia depend on patch connectivity, area, and quality. We then show that habitat networks in six extant metapopulations in 16-km2 squares were larger, had longer modeled persistence times (using IFM), and higher metapopulation capacity (lambdaM) than six extinct metapopulations. However, there was a > 99% chance that one or more of the six extant metapopulations would go extinct in 100 years in the absence of further habitat loss. For 11 out of 12 networks, minimum areas of habitat needed for 95% persistence of metapopulation simulations after 100 years ranged from 80 to 142 ha (approximately 5-9% of land area), depending on the spatial location of habitat. The area of habitat exceeded the estimated minimum viable metapopulation size (MVM) in only two of the six extant metapopulations, and even then by only 20%. The remaining four extant networks were expected to suffer extinction in 15-126 years. MVM was consistently estimated as approximately 5% of land area based on a sensitivity analysis of IFM parameters and was reduced only marginally (to approximately 4%) by modeling the potential impact of long-distance colonization over wider landscapes. The results suggest a widespread extinction debt among extant metapopulations of a declining species, necessitating conservation management or reserve designation even in apparent strongholds. For threatened species, metapopulation modeling is a potential means to identify landscapes near to extinction thresholds, to which conservation measures can be targeted for the best chance of success.  相似文献   
100.
Price MV  Campbell DR  Waser NM  Brody AK 《Ecology》2008,89(6):1596-1604
Despite extensive study of pollination and plant reproduction on the one hand, and of plant demography on the other, we know remarkably little about links between seed production in successive generations, and hence about long-term population consequences of variation in pollination success. We bridged this "generation gap" in Ipomopsis aggregata, a long-lived semelparous wildflower that is pollinator limited, by adding varying densities of seeds to natural populations and following resulting plants through their entire life histories. To determine whether pollen limitation of seed production constrains rate of population growth in this species, we sowed seeds into replicated plots at a density that mimics typical pollination success and spacing of flowering plants in nature, and at twice that density to mimic full pollination. Per capita offspring survival, flower production, and contribution to population increase (lambda) did not decline with sowing density in this experiment, suggesting that typical I. aggregata populations freed from pollen limitation will grow over the short term. In a second experiment we addressed whether density dependence would eventually erase the growth benefits of full pollination, by sowing a 10-fold range of seed densities that falls within extremes estimated for the natural "seed rain" that reaches the soil surface. Per capita survival to flowering and age at flowering were again unaffected by sowing density, but offspring size, per capita flower production, and lambda declined with density. Such density dependence complicates efforts to predict population dynamics over the longer term, because it changes components of the life history (in this case fecundity) as a population grows. A complete understanding of how constraints on seed production affect long-term population growth will hinge on following offspring fates at least through flowering of the first offspring generation, and doing so for a realistic range of population densities.  相似文献   
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