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61.
We conducted a 6-year longitudinal behavioral and genetic investigation of a highly polygynous pinniped, the northern fur seal (Callorhinus ursinus), to determine the contribution of terrestrial polygyny to male fertilization success and to assess the occurrence of alternative mating strategies. Genetic samples from 37 adult males, 50 adult females, and 85 pups were collected and genotyped using five polymorphic microsatellite loci. Pup paternity was assigned using Cervus 2.0 at 99% confidence level. Paternity of 83 pups (98%) was assigned to terrestrial males who held territories or stayed temporarily in the study area during the breeding season when fertilization occurred. For 56 pups of which attendance records of their mothers were available, paternity of 45 pups (80%) was assigned to the associate males in whose territory their mothers stayed during the perioestrus period. In addition to defending breeding territories, territorial males have often been observed attempting to forcibly abduct adult females from adjacent territories (female stealing): We observed a total of 95 such cases, in which the stealers had significantly fewer females than the territorial males from whose territories they stole females. Our results indicate that terrestrial resource-defense polygyny is the major mating system in this species and that nonassociated paternity occurs mostly as a result of alternative mating strategies of less successful males. Male northern fur seals thus appear to adopt conditional alternative strategies that depend on their current social status to maximize their life-time reproductive success.  相似文献   
62.
Females sometimes obtain older sires for their offspring through extra-pair interactions, but how female age influences paternity is largely unexplored and interactive effects across the age span of both sexes have not been analyzed. To test whether female choice of sire age varies with female age in the blue-footed booby (Sula nebouxii), we examined associations between ages of both partners and the probability of extra-pair paternity (EPP) in 350 broods of parents up to 22 years old in a single breeding season. Extra-pair paternity enables a female to select an alternative sire for her offspring and could function to avoid or achieve particular combinations of parental ages. A male age?×?female age interaction revealed that in young females (≤4 years), EPP decreased with increasing age of the social partner, whereas in old females (≥8 years), it increased. Moreover, sires of extra-pair (EP) chicks of young females paired to young males were on average 6.33 years older than the females’ social partners. Since female boobies control copulatory access, this pattern could imply that young females choose old sires for their proven genetic quality and that old females avoid very old males because matings with them may risk infertility or genetic defects in offspring. Taking female age into account and observing across the whole age span may be necessary for understanding female age-based mate choice.  相似文献   
63.
Remediation technologies can sometimes be established, but are not prevalent, for a variety of reasons; however, they can be subject to the forces of change. In some cases, creative economics promotes new uses, but also process improvements can drive new applications and levels of acceptance. This is what is happening with the deployment of horizontal wells for site assessment and remediation. In essence, decreasing costs and a strategic shift, which can be characterized as “greater flexibility,” are two factors that have brought about a resurgence of horizontal well systems. The latter is specifically tied to moving from monolithic single well systems to segmented well systems and this article explains how this is a next‐generation advancement in site assessment and remediation. As one example, nested, discrete horizontal profiling brings additional accuracy to assessment at sites, especially those challenged by access issues and also provides more directed treatment operations with a unique flexibility in dynamic groundwater systems. Also, with horizontal nested well systems, conceptual site models can be significantly enhanced with new perspectives and, depending on the situation, may provide significant economic advantages in deployment. Finally, this technological advancement creates a new paradigm in contrast, or rather as an adjunct, to vertical profiling and high‐resolution site characterization. In fact, it opens up a new strategic approach that can be called high‐resolution contaminant distribution, because flexible horizontal segmented well systems can be used to navigate “up the spine of the plume” providing discretized data sets that illuminate contaminant distribution in new ways.  相似文献   
64.
65.
Methods for determining individual exposure to volatile organic compounds (VOC) during normal daily activities were field tested on university student volunteers in Texas and North Carolina. The equipment tested included a personal monitor employing Tenax GC® to collect organic vapors for later analysis by GC-MS, and a specially designed spirometer for collecting samples of expired human breath on duplicate Tenax cartridges. The personal monitor and spirometer proved feasible for collecting abundant quantitative data on most of the 15 target organics. Air exposures to many VOC varied widely, sometimes over three orders of magnitude, among students on the same campus who had been monitored over the same time period and day. A log-linear relationship between breathing-zone air exposures and concentrations in exhaled breath was suggested for three chemicals: tetrachloroethylene, 1,1,1-trichloroethane, and vinylidene chloride. Air was the main route of exposure for all target compounds except the two trihalomethanes (chloroform and bromodichloromethane), which were transmitted mainly through water. Estimated total daily intake through air and water of the target organics ranged from 0.3 to 12.6 mg, with 1,1,1-trichloroethane at the highest concentrations in both geographic areas.  相似文献   
66.
Flood control failure: San Lorenzo River,California   总被引:2,自引:0,他引:2  
The San Lorenzo River on the central California coast was the site of a major US Army Corps of Engineers flood control project in 1959. By excavating the channel below its natural grade and constructing levees, the capacity of the river was increased in order to contain approximately the 100 year flood. Production and transport of large volumes of sediment from the river's urbanizing watershed has filled the flood control project with sand and silt. The natural gradient has been re-established, and flood protection has been reduced to containment of perhaps the 30 year flood. In order for the City of Santa Cruz, which is situated on the flood plain, to be protected from future flooding,it must either initiate an expensive annual dredging program, or replan and rebuild the inadequately designed flood control channel. It has become clear, here and elsewhere, that the problem of flooding cannot simply be resolved by engineering. Large flood control projects provide a false sense of security and commonly produce unexpected channel changes.  相似文献   
67.
We tested a data-driven ‘traditional’ model and a schema-driven ‘categorization’ model of rater cognitive processes. Raters viewed one of two videotaped lectures on economics. Next, they completed dimensional and overall performance ratings, and scales designed to measure performance-based and non-performance-based aspects of raters' general impressions. We tested model predictions using a combination of confirmatory factor analysis and single-equation regression estimates of structural parameters. Neither model received unequivocal support, though results favored the categorization model. We conclude that (a) performance-based and non-performance-based aspects of a rater's general impression can be distinguished empirically, (b) raters' overall impressions of ratees may substantially reflect the integration of performance-based information, and (c) performance evaluation may be better viewed in the context of ‘evaluation-based’ rather than ‘memory-based’ judgments.  相似文献   
68.
The US Army Corps of Engineers, the US Bureau of Reclamation, and the Bonneville Power Administration initiated the Columbia River System Operation Review (SOR) in 1990. The SOR will assist agencies in comparing the benefits and risks to Columbia River uses and natural resources from alternative strategies for using Columbia River water. Focusing on 14 federal dams within the basin, the agencies are attempting to improve on the efficient and coordinated use of the Columbia River system. An initial screening of all potential strategies of reservoir operation was necessary to reduce the number of possibilities to a limited set for detailed analysis. To that end, the Resident Fish Work Group of the SOR developed spreadsheet models capable of assessing the impacts of different management strategies on resident fish at six storage reservoirs. The models include biological, physical, and hydrological relationships important to resident fish specific to each reservoir. Alternatives that kept the reservoirs near full pool and held stable during the growing season resulted in positive benefits to resident fish at all locations modeled. Conversely, alternatives designed to improve anadromous fish survival with increased instream flow generally had a negative impact on the resident fish in the reservoirs modeled. The models developed for resident fish in the screening analysis phase of the SOR were useful in assessing the relative impact to resident fish from a large number of alternatives. The screening analysis demonstrated that future analytical efforts must consider trade-offs among river uses/resource groups, among reservoirs throughout the basin, and among resident fish species within a reservoir.Pacific Northwest Laboratory is operated by Battelle Memorial Institute for the US Department of Energy under contract DE-AC06-76RLO 1830.  相似文献   
69.
Including past and present impacts in cumulative impact assessments   总被引:6,自引:0,他引:6  
Environmental concerns such as loss of biological diversity and stratospheric ozone depletion have heightened awareness of the need to assess cumulative impacts in environmental documents. More than 20 years of experience with the National Environmental Policy Act (NEPA) have provided analysts in the United States with opportunities for developing successful techniques to assess site-specific impacts of proposed actions. Methods for analyzing a proposed action's incremental contribution to cumulative impacts are generally less advanced than those for project-specific impacts.The President's Council on Environmental Quality (CEQ) defines cumulative impact to include the impacts of past, present and reasonably foreseeable future actions regardless of who undertakes the action. Court decisions have helped clarify the distinction between reasonably foreseeable future actions and other possible future actions. This paper seeks to clarify how past and present impacts should be included in cumulative impact analyses.The definition of cumulative impacts implies that cumulative impact analyses should include the effects of all past and present actions on a particular resource. Including past and present impacts in cumulative impact assessments increases the likelihood of identifying significant impacts. NEPA requires agencies to give more consideration to alternatives and mitigation and to provide more opportunities for public involvement for actions that would have significant impacts than for actions that would not cause or contribute to significant impacts. For an action that would contribute to significant cumulative impacts, the additional cost and effort involved in increased consideration of alternatives and mitigation and in additional public involvement may be avoided if the action can be modified so that its contributions to significant cumulative impacts are eliminated.Managed by Lockheed Martin Energy Research Corporation under contract DE-AC05-84OR21400 with the US Department of Energy.  相似文献   
70.
The Windsor, Ontario Exposure Assessment Study evaluated the contribution of ambient air pollutants to personal and indoor exposures of adults and asthmatic children living in Windsor, Ontario, Canada. In addition, the role of personal, indoor, and outdoor air pollution exposures upon asthmatic children's respiratory health was assessed. Several active and passive sampling methods were applied, or adapted, for personal, indoor, and outdoor residential monitoring of nitrogen dioxide, volatile organic compounds, particulate matter (PM; PM-2.5 pm [PM2.5] and < or =10 microm [PM10] in aerodynamic diameter), elemental carbon, ultrafine particles, ozone, air exchange rates, allergens in settled dust, and particulate-associated metals. Participants completed five consecutive days of monitoring during the winter and summer of 2005 and 2006. During 2006, in addition to undertaking the air pollution measurements, asthmatic children completed respiratory health measurements (including peak flow meter tests and exhaled breath condensate) and tracked respiratory symptoms in a diary. Extensive quality assurance and quality control steps were implemented, including the collocation of instruments at the National Air Pollution Surveillance site operated by Environment Canada and at the Michigan Department of Environmental Quality site in Allen Park, Detroit, MI. During field sampling, duplicate and blank samples were also completed and these data are reported. In total, 50 adults and 51 asthmatic children were recruited to participate, resulting in 922 participant days of data. When comparing the methods used in the study with standard reference methods, field blanks were low and bias was acceptable, with most methods being within 20% of reference methods. Duplicates were typically within less than 10% of each other, indicating that study results can be used with confidence. This paper covers study design, recruitment, methodology, time activity diary, surveys, and quality assurance and control results for the different methods used.  相似文献   
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