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61.
62.
Wesley H. Blood Calvin G. Clyde Dean F. Peterson 《Journal of the American Water Resources Association》1971,7(4):785-801
ABSTRACT .Desalting plants can provide a means of firming up erratic natural supplies when properly operated in conjunction with existing water supply reservoir systems. Since the natural inflow is variable, the choice of when to run the desalting plant is difficult. If the plant is turned on too late, a shortage may result; or if the plant runs too long, costly water may be wasted. A computer program is described that can help water planners find an optimal operating rule, i.e., a policy that tells when to turn the plant on and off to meet a given demand. Criteria for defining the firm water yield of the system (with and without desalting) are first defined. The logic of the program is then described. The program, written in FORTRAN IV, successively simulates operation of the given size reservoir-desalting plant system under control of various operating rules and selects the optimal rule as the one which produces the required firm water yield at the least unit cost. The optimal plant size and the staging of construction can also be studied by making a series of computations. Applications of the Operating Rule Program to water systems in California, Utah and New York are described. The studies show that, compared with base load operation, substantial savings are possible if optimum intermittent conjunctive operation of the desalting plant is followed. 相似文献
63.
Numerical calculations for a model of the near-shore circulation in a lake subject to two diurnal forcing mechanisms are presented. The first mechanism is a heating/cooling term in the heat equation representing the daytime heating and nighttime cooling of the diurnal cycle. The second is a periodic surface stress modelling a sea-breeze/gully wind system typical of some coastal regions. The two forcing mechanisms can either act together or against each other depending on their relative phase. The numerical solutions are compared with previously published analytical solutions and used to explore the extra dynamics associated with non-linear effects (specifically advection). The latter dynamics include the formation of gravity currents and unstable density profiles leading to secondary circulation. 相似文献
64.
内分泌干扰物 (Endocrine Disrupting Compounds, EDCs)可以通过干扰下丘脑-垂体-性腺(HPG)轴来影响生殖系统。虽然目前已有筛选内分泌干扰物的体外检测方法,但这些方法在用于体内实验时却有着不稳定的准确性。本文记录了以黑头呆鱼(Pimephales promelas)的下丘脑-垂体-性腺轴与肝(HPG-L)的共培养组织作为组织外植体来模拟体内反应的结果。我们对成年鱼的大脑(下丘脑),垂体,性腺和肝进行了单独和共同培养的检测来确定可以在体内重复的情况与组合。只有共培养体表现出去甲雄三烯醇酮对于雌二醇,睾酮和卵黄生成素生成趋势的影响。较低的暴露剂量会抑制激素生成,而较高的暴露剂量则会促进激素生成,形成U型作用曲线。这些数据表明下丘脑-垂体-性腺-肝轴的全部组织的共同培养可以作为体内实验与体外实验的连接,从而预测在完整生物体内内分泌系统的扰乱。本实验中以组织为基础的下丘脑-垂体-性腺-肝系统作为一个灵活的体内系统的解构版本得到了更好的实验控制。通过分离、审查和重组需要的组织,我们能够检测到生物系统功能与对于内分泌干扰物反应中的微小变化。
精选自Theresa K. Johnston, Edward Perkins, Duncan C. Ferguson, Donald M. Cropek. Tissue explant co-culture model of the hypothalamic-pituitary-gonadal-liver axis of the fathead minnow (Pimephales promelas) as a predictive tool for endocrine disruption. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2530–2541, October 2016.
DOI: 10.1002/etc.3415
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3415/full 相似文献
65.
Jennyffer Cruz Duncan R. Sutherland Dean P. Anderson Alistair S. Glen Paul J. de Tores Luke K.-P. Leung 《Behavioral ecology and sociobiology》2013,67(8):1329-1338
Antipredator behavior studies generally assess prey responses to single predator species although most real systems contain multiple species. In multi-predator environments prey ideally use antipredator responses that are effective against all predator species, although responses may only be effective against one predator and counterproductive for another. Multi-predator systems may also include introduced predators that the prey did not co-evolve with, so the prey may either fail to recognize their threat (level 1 naiveté), use ineffective responses (level 2 naiveté) or succumb to their superior hunting ability (level 3 naiveté). We analyzed microhabitat selection of an Australian marsupial (koomal, Trichosurus vulpecula hypoleucus) when faced with spatiotemporal differences in the activity/density levels of one native (chuditch, Dasyurus geoffroii) and two introduced predators (red fox, Vulpes vulpes; feral cat, Felis catus). From this, we inferred whether koomal recognized introduced predators as a threat, and whether they minimized predation risk by either staying close to trees and/or using open or dense microhabitats. Koomal remained close to escape trees regardless of the predator species present, or activity/density levels, suggesting koomal employ this behavior as a first line of defense. Koomal shifted to dense cover only under high risk scenarios (i.e., with multiple predator species present at high densities). When predation risk was low, koomal used open microhabitats, which likely provided benefits not associated with predator avoidance. Koomal did not exhibit level 1 naiveté, although further studies are required to determine if they exhibit higher levels of naiveté (2–3) against foxes and cats. 相似文献
66.
For many decades, fisheries research has focused on stock assessment and the impact of the fishery effort on resources. Although this knowledge remains necessary, a more integrated analysis of the joint dynamics of resource and operational activities is needed to provide more useful advice for the management of fishery systems. Since 1994 a new approach to fishery science has been carried out for Cameroonian small-scale fisheries, the aim being the incorporation into fishery science of research on fishery management, fishing processes and fishermen's behaviour. This paper presents a more systemic data approach which combines biological parameters and operational factor analyses with the goal of sustainable development. From two years of data collected on the purse seine fishing units operating in the Bay of Biafra (2002 and 2003), a set of three correspondence analyses is applied: (1) to the length frequency distribution of Ethmalosa fimbriata, (2) to the number of visits per fishing ground, and (3) to the species appearance frequency in the landings. These three analyses were plotted per month-year period. The results are presented in the form of an annual exploitation cycle, linking fishing grounds, the main species caught, and corresponding fishing period. 相似文献
67.
Duncan McLaren 《Process Safety and Environmental Protection》2012,90(6):489-500
The paper summarises a global assessment of around 30 prospective negative emissions techniques (NETs) found in the literature. Fourteen techniques including direct air capture, BECCS, biochar, and ocean alkalinity enhancement are considered in more detail.The novel functional categorisation of NETs developed in the course of the assessment is set out and a comparative quantitative summary of the results is presented, focusing on the relative readiness, global capacity, costs and side-effects of the prospective NETs.Both technology specific and more generic potential limitations are discussed, notably those arising from energy requirements, from availability of geological storage capacity and from sustainable supply of biomass.Conclusions are drawn regarding the overall scope of NETs to contribute to safe carbon budgets, and challenges arising in the future governance of NETs, with particular reference to the potential role of carbon markets. 相似文献
68.
The International Union for Conservation of Nature's Red List of Threatened Species (RLS) is the key global tool for objective, repeatable assessment of species’ extinction risk status, and plays an essential role in tracking biodiversity loss and guiding conservation action. Satellite remote sensing (SRS) data sets on global ecosystem distributions and functioning show exciting potential for informing range-based RLS assessment, but their incorporation has been restricted by low temporal resolution and coverage of data sets, lack of incorporation of degradation-driven habitat loss, and noninclusion of assumptions related to identification of changing habitat distributions for taxa with varying habitat dependency and ecologies. For poorly known mangrove-associated Cuban hutias (Mesocapromys spp.), we tested the impact of possible assumptions regarding these issues on range-based RLS assessment outcomes. Specifically, we used annual (1985–2018) Landsat data and land-cover classification and habitat degradation analyses across different internal time series slices to simulate range-based RLS assessments for our case study taxa to explore potential assessment uncertainty arising from temporal SRS data set coverage, incorporating proxies of (change in) habitat quality, and assumptions on spatial scaling of habitat extent for RLS parameter generation. We found extensive variation in simulated species-specific range-based RLS assessments, and this variation was mostly associated with the time series over which parameters were estimated. However, results of some species-specific assessments differed by up to 3 categories (near threatened to critically endangered) within the same time series, due to the effects of incorporating habitat quality and the spatial scaling used in RLS parameter estimation. Our results showed that a one-size-fits-all approach to incorporating SRS information in RLS assessment is inappropriate, and we urge caution in conducting range-based assessments with SRS for species for which habitat dependence on specific ecosystem types is incompletely understood. We propose novel revisions to parameter spatial scaling guidelines to improve integration of existing time series data on ecosystem change into the RLS assessment process. 相似文献
69.
Yasuko Yoshida Bryan N. Duncan Christian Retscher Kenneth E. Pickering Edward A. Celarier Joanna Joiner K. Folkert Boersma J. Pepijn Veefkind 《Atmospheric environment (Oxford, England : 1994)》2010,44(11):1443-1448
The impact of Hurricanes Katrina and Rita in 2005 on pollution emissions in the Gulf of Mexico region was investigated using tropospheric column amounts of nitrogen dioxide (NO2) from the Ozone Monitoring Instrument (OMI) on the NASA Aura satellite. Around New Orleans and coastal Mississippi, we estimate that Katrina caused a 35% reduction in NOx emissions on average in the three weeks after landfall. Hurricane Rita caused a significant reduction (20%) in NOx emissions associated with power generation and intensive oil refining activities near the Texas/Louisiana border. We also found a 43% decrease by these two storms over the eastern Gulf of Mexico Outer Continental Shelf mainly due to the evacuation of and damage to platforms, rigs, and ports associated with oil and natural gas production. 相似文献
70.
The intensity of management of lowland grassland fields in the United Kingdom, coupled with the fact that such grasslands dominate much of the lowland landscape, means that there are now few opportunities for many plants, invertebrates, birds, or mammals to survive. The Scottish Agricultural College (SAC) has investigated whether fencing off the margins of such fields next to watercourses to control diffuse pollution has any positive impacts on biodiversity, based on assessments of vegetation composition and condition and structure of assemblages of invertebrates of importance as foodstuffs to farmland birds. Fencing watercourses increased the abundance of key groups of invertebrates. However, the invertebrate species diversity was not increased unless the margins were ≥ 5.4 m in width. Margins established in the study area to prevent access by livestock to watercourses or to enhance biodiversity are generally ≤ 2.6 m wide and are therefore unlikely to provide conditions for additional invertebrate species to use. The dense, tall swards within such margins are also unlikely to provide foraging opportunities for farmland birds. Management (such as low-intensity grazing by livestock in the margins) is essential to provide the conditions required for these groups, but this could conflict with the diffuse pollution mitigation aims. A compromise is proposed whereby limited autumn/winter grazing by livestock could be used to open the vegetation structure in the margins. Grazing by livestock at that time may be acceptable since it is not occurring in the period of main diffuse pollution concern (i.e., the fecal contamination of watercourses and bathing waters in the spring and summer). It is also essential that a landscape-scale approach is taken, driven by knowledge of the full needs of the species concerned, when deciding where best to target agri-environmental actions aimed at farmland bird conservation. 相似文献