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81.
Rogers CM 《Conservation biology》2011,25(6):1212-1219
Populations of landbirds (bird species that occupy terrestrial habitats for most of their life cycle) are declining throughout North America (north of Mexico) and Europe, yet little is known about how demography is driving this trend. A recent model of 5 geographically separated populations of Cerulean Warblers (Dendroica cerulea) that was based on within-season sampling of nest survival and fledgling success shows that all populations are sinks (annual reproduction is consistently less than annual adult mortality). I tested this indirect model by directly measuring fecundity (number of female fledglings/female) during the breeding season for 2 years in a Cerulean Warbler population occupying a mature forest in southwestern Michigan (U.S.A.) I determined territories of male birds on the basis of male plumage characters and phases of the nesting cycle (2007) and on uniquely color-banded males (2008). I transferred locations of identified males to topographic maps. I counted all fledglings in territories from May to July each year. The model I tested may apply only to single-brooded species; therefore, I searched the literature to estimate the percentage of single-brooded species in North America. The breeding season of Cerulean Warblers was short- nearly all nests were initiated from mid-May to late June. Nest predation and brood parasitism were primary and rare causes of nest failure, respectively. Significantly fewer Cerulean Warblers fledged from parasitized than from nonparasitized nests. Fledgling survival required to maintain the population size was well above previously published values for Neotropical migrants. Single-brooded species comprise 62% of North American breeding bird species for which the number of broods per year is known; I believe my results may apply to these species. The consistency between identification of populations as sources or sinks on the basis of either model estimates or direct measurements suggests that a demographic model relying on within-season sampling of fecundity is adequate to determine population status of single-brooded avian populations. In addition, on the basis of results of previous studies, annual adult survival rate of the Cerulean Warbler is typical of parulid warblers that are not declining. Thus, low fecundity, here determined with different quantitative methods, can drive status of landbird species with high-observed survival. 相似文献
82.
Quantitative risk analysis is in principle an ideal method to map one’s risks, but it has limitations due to the complexity of models, scarcity of data, remaining uncertainties, and above all because effort, cost, and time requirements are heavy. Also, software is not cheap, the calculations are not quite transparent, and the flexibility to look at various scenarios and at preventive and protective options is limited. So, the method is considered as a last resort for determination of risks. Simpler methods such as LOPA that focus on a particular scenario and assessment of protection for a defined initiating event are more popular. LOPA may however not cover the whole range of credible scenarios, and calamitous surprises may emerge.In the past few decades, Artificial Intelligence university groups, such as the Decision Systems Laboratory of the University of Pittsburgh, have developed Bayesian approaches to support decision making in situations where one has to weigh gains and costs versus risks. This paper will describe details of such an approach and will provide some examples of both discrete random variables, such as the probability values in a LOPA, and continuous distributions, which can better reflect the uncertainty in data. 相似文献
83.
Specificity and sensitivity of microsatellite markers for the identification of larvae 总被引:1,自引:0,他引:1
The identification of larval marine invertebrates to species or even higher taxonomic levels by morphological examination is notoriously difficult. Many diagnostic features are absent or poorly formed at early stages in development. This is particularly true for the larvae of bivalve molluscs, for which a routine and accurate method of identification would prove valuable to both ecologists and fishery managers. A simple molecular genetic method to identify specifically larvae of the European oyster, Ostrea edulis L., 1758, is presented. The test is based on PCR amplification of highly species-specific microsatellite loci and is sensitive enough to register the presence of a single larval individual (~200 µm width) in a mixed sample of 20 mg wet weight plankton (approximately 250 larval animals). This work demonstrates that microsatellite loci can be used as highly sensitive and specific taxonomic indicators, for studies of planktonic larvae. Details of three novel microsatellite loci are also given for O. edulis, increasing the suite of molecular tools available for use in population genetic studies of this commercially important species. 相似文献
84.
Chirstopher D. Rogers 《Natural resources forum》1979,3(4):337-348
The paper reviews progress in the individual commodity negotiations for non-fuel minerals covered by the Integrated Programme for Commodities (IPC). Given the minimal progress to date, the author reconsiders the objectives of the IPC to gauge the extent to which they meet the needs of countries engaged in mineral production or trade. It is suggested that the major focus of the IPC be towards price stability, with less attention to other aspects of market instability and other market problems. For this reason, the IPC discussions have failed to focus on such major issues of concern in the mineral sector as measures necessary to guarantee adequate supplies of minerals over the long-term, the financing of the required investments, the expansion of production by developing countries and the securing of price levels sufficient to generate appropriate returns on capital employed. Cet article est consacré à l'étude des progrès accomplis en matière de négociations individuelles sur les produits de base concernant les minéraux non-combustibles qui figurent au Programme intégré pour les produits de base. Etant donné les résultats peu concluants qui ont été enregistrés, ‘auteur examine à nouveau les objectifs du programme pour évaluer jusqu’ à quel point ils répondent aux besoins des pays engagés dans la production ou le commerce de minéraux. Selon cet article, ‘accent principal du programme a été mis sur’ instabilité en matière de prix au détriment d'autres aspects de 'instabilité du marché et d'autres problèmes connexes. De telles discussions ont éludé les points d'intérét majeurs du secteur minier, à savoir, les mesures nécessaires à assurer à long terme des approvisionnements suffisants en minéraux, le financement des investissements nécessaires, une participation plus active des pays en développement à 'expansion de la production et le maintien de niveaux de prix susceptibles de créer des profits suffisants sur le capital investi. Este artículo revisa los progresos alcanzados en la negociación individual de minerales no combustibles cubiertos por el programs ‘Integrated Programme for Commodities’ (IPC). Dado el progreso mínimo presente, el autor reconsidera los objectivos de la IPC para apreciar el grado en que estos objectivos se ajustan a las necesidades de los países dedicados a la producción y comercio de minerales. Se sugiero que el IPC enfoca su acción a la estabilidad de precios, con menor atención a otros aspectos de inestabilidad y otros problemas de mercado. Por esta razón las discuciones de IPC no han considerado asuntos de tanta importancia en el sector minero tales como las medidas para garantizar suministros adecuados de minerales por largos plazos, el financimiento de las inversiones requeridas, la expansión de la producción por los países en desarollo y la garantía de niveles de precios suficientes para generar retornos adecuados del capital invertido. 相似文献
85.
Peter Rogers 《Natural resources forum》1993,17(2):117-131
This paper reviews the phenomenon of international river basins, and concludes that the sharing of river basins between and among countries is the rule rather than the exception for the major river systems of the world. The growth of the nation state with rivers as agreed-upon boundaries, as cease-fire lines and as natural defensive lines has led to the carving up of most river basins around the world. More than 200 river basins, accounting for more than 50% of the land area of the Earth, are shared by two or more countries. When population densities were low, there was plenty of water for all and major conflicts were avoided. With the rapid population and economic growth experienced in the past few decades, conflicts over use of water are becoming more important. It is expected that in the near future such conflicts will become much more severe. The paper reviews the literature on attempts to analyse river basin conflicts and negotiate solutions. Some rudimentary game models are examined, and some tentative conclusions, based upon various game theory concepts of stability, are applied to the Ganges-Brahmaputra basin. The paper ends with suggestions on how to plan Pareto-Admissible outcomes for international basins. 相似文献
86.
Luciano Farias de Novaes Bruna Luckmann Saratt José Alberto Domingues Rodrigues Suzana Maria Ratusznei Deovaldo de Moraes Rogers Ribeiro Marcelo Zaiat Eugenio Foresti 《Journal of environmental management》2010,91(8):1647-1656
The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1 m3, treated 0.65 m3 sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were assessed for each reactor configuration: flat-blade turbine impeller, 45°-inclined-blade turbine impeller and helix impeller, as well as two agitation rates: 40 and 80 rpm, resulting in a combination of six experimental conditions. In addition, the ASBR was also operated at 20 rpm with a flat-blade turbine impeller and the AnSBBR was operated with a draft tube and helix impeller at 80 and 120 rpm. To quantify how impeller type and agitation rate relate to substrate consumption rate, results obtained during monitoring at the end of the cycle, as well as the time profiles during a cycle were analyzed. Increasing agitation rate from 40 rpm to 80 rpm in the AnSBBR improved substrate consumption rate whereas in the ASBR this increase destabilized the system, likely due to granule rupture caused by the higher agitation. The AnSBBR showed highest solids and substrate removal, highest kinetic constant and highest alkalinity production when using a helix impeller, 80 rpm, and no draft tube. The best condition for the ASBR was achieved with a flat-blade turbine impeller at 20 rpm. The presence of the draft tube in the AnSBBR did not show significant improvement in reactor efficiency. Furthermore, power consumption studies in these pilot scale reactors showed that power transfer required to improve mass transfer might be technically and economically feasible. 相似文献
87.
The Precautionary Principle has emerged in response to the need for an effective method for dealing with risks and uncertainties in environmental management. In essence, the Principle requires action to prevent serious and irreversible damage even before harm can be scientifically demonstrated or economically assessed. Proponents argue that the Principle should be applied in situations where both the probability and value of irreversible damage are unknown. The lack of these particular data prevent a full cost–benefit analysis, but permit application of the Principle through the defensive-expenditure approach. How much would the community be required to pay to fund alternatives to maintain the environment and so defend existing levels of utility? Through the application of risk analysis and the stochastic dominance technique, a range of options and outcomes can be examined incorporating the using available information within a framework consistent with economic rationality. An extended risk simulation is applied to an environmental issue where there is a risk of serious and irreversible damage to the environment, namely, protection of the Barmah-Millewa forest-wetland in Australia. 相似文献
88.
Environmental and Ecological Statistics - An extensive number of studies uses trade-to-GDP as a proxy for globalisation in environmental research. Globalisation encompasses much more than just... 相似文献
89.
Emergency managers who work on floods and other weather‐related hazards constitute critical frontline responders to disasters. Yet, while these professionals operate in a realm rife with uncertainty related to forecasts and other unknowns, the influence of uncertainty on their decision‐making is poorly understood. Consequently, a national‐level survey of county emergency managers in the United States was administered to examine how they interpret forecast information, using hypothetical climate, flood, and weather scenarios to simulate their responses to uncertain information. The study revealed that even emergency managers with substantial experience take decision shortcuts and make biased choices, just as do members of the general population. Their choices vary depending on such features as the format in which probabilistic forecasts are presented and whether outcomes are represented as gains or losses. In sum, forecast producers who consider these decision processes when developing and communicating forecasts could help to improve flood preparation and potentially reduce disaster losses. 相似文献
90.
Lewis H. Rogers 《Journal of the Air & Waste Management Association (1995)》2013,63(9):845-846
It is gratifying to report that 1975-1976 has been another year of increased activity for the Air Pollution Control Association, and various indicators are positive compared to previous years. Membership has increased, attendance at meetings has increased, we have a substantial surplus to report, there is increased activity in membership interest and in our overall activity. Public affairs involvement has increased somewhat, as have our international activities. Local sections and technical committees have expanded their scope of productive involvement. Clearly, APCA has had a successful and productive year. 相似文献