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81.
The investigation concerns the impact of the new school environment on a group of 50 male and female children aged 11–16 years, who leave home to reside temporarily at boarding school, in terms of the characteristics of problems and worries reported and the incidence of spontaneous reports of homesickness. More problems relating to the school than to the home environment were reported but proportionally more worry units were reported associated with home problems for both males and females. There was no sex differences in this respect. The reported level of spontaneously reported homesickness was 16% and there were no sex differences. Factors such as age, geographical distance of move and decision to go away to school were not influential in determining the level of reported problems or incidence of spontaneous reports of homesickness. A relationship was found with level of problems reported and recent life history but the result proved difficult to interpret. 相似文献
82.
83.
The role of organic solutes in the osmotic adjustment processes of the marine macroalga Enteromorpha intestinalis (L.) Link was investigated in 1986, using fresh samples collected from mid-shore rock pools at Tayport, Fife, Scotland. Natural-abundance 13C nuclear magnetic-resonance spectroscopy revealed -dimethylsulphoniopropionate (DMSP) to be the only major low molecular weight organic osmolyte present. However, on transfer to a hypersaline medium (300% sea water; 100%=35 S), tissue sucrose and proline levels increased markedly, while DMSP remained constant. Recovery of optimal photosynthetic activity and increases in inorganic ion levels occurred over a similar time scale to the changes in sucrose and proline (within 48 h), indicating that these two organic solutes are involved in hyperosmotic adjustment in E. intestinalis while DMSP is not. Freshly-collected plants transferred to 300% sea water medium in the dark showed no significant increases in organic osmolytes. In contrast, starch-enrichment (16 d continuous illumination) led to enhanced synthesis of sucrose and proline in the light and in darkness, but tissue DMSP levels showed no variation throughout. These observations suggest that DMSP is not involved in short-term osmoacclimation in E. intestinalis. 相似文献
84.
Study of metabolites from the degradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial consortium enriched from mangrove sediments 总被引:3,自引:0,他引:3
The PAH metabolites produced during degradation of fluorene, phenanthrene and pyrene by a bacterial consortium enriched from mangrove sediments were analyzed using the on-fiber silylation solid-phase microextraction (SPME) combining with gas chromatography–mass spectrometry (GC–MS) method. Seventeen metabolites at trace levels were identified in different PAH degradation cultures based on the full scan mass spectra. In fluorene degradation cultures, 1-, 2-, 3- and 9-hydroxyfluorene, fluorenone, and phthalic acid were detected. In phenanthrene and pyrene degradation cultures, various common metabolites such as phenanthrene and pyrene dihydrodiols, mono-hydroxy phenanthrene, dihydroxy pyrene, lactone and 4-hydroxyphenanthrene, methyl ester, and phthalic acid were found. The detection of various common and novel metabolites demonstrates that SPME combining with GC–MS is a quick and convenient method for identification as well as monitoring the real time changes of metabolite concentrations throughout the degradation processes. The knowledge of PAH metabolic pathways and kinetics within indigenous bacterial consortium enriched from mangrove sediments contributes to enhance the bioremediation efficiency of PAH in real environment. 相似文献
85.
A systematic review of systematic reviews and meta-analyses of animal experiments with guidelines for reporting 总被引:1,自引:0,他引:1
Peters JL Sutton AJ Jones DR Rushton L Abrams KR 《Journal of environmental science and health. Part. B》2006,41(7):1245-1258
To maximize the findings of animal experiments to inform likely health effects in humans, a thorough review and evaluation of the animal evidence is required. Systematic reviews and, where appropriate, meta-analyses have great potential in facilitating such an evaluation, making efficient use of the animal evidence while minimizing possible sources of bias. The extent to which systematic review and meta-analysis methods have been applied to evaluate animal experiments to inform human health is unknown. Using systematic review methods, we examine the extent and quality of systematic reviews and meta-analyses of in vivo animal experiments carried out to inform human health. We identified 103 articles meeting the inclusion criteria: 57 reported a systematic review, 29 a systematic review and a meta-analysis, and 17 reported a meta-analysis only. The use of these methods to evaluate animal evidence has increased over time. Although the reporting of systematic reviews is of adequate quality, the reporting of meta-analyses is poor. The inadequate reporting of meta-analyses observed here leads to questions on whether the most appropriate methods were used to maximize the use of the animal evidence to inform policy or decision-making. We recommend that guidelines proposed here be used to help improve the reporting of systematic reviews and meta-analyses of animal experiments. Further consideration of the use and methodological quality and reporting of such studies is needed. 相似文献
86.
H. Resit Akçakaya Ana S. L. Rodrigues David A. Keith E. J. Milner-Gulland Eric W. Sanderson Simon Hedges David P. Mallon Molly K. Grace Barney Long Erik Meijaard P. J. Stephenson 《Conservation biology》2020,34(3):561-571
Species interactions matter to conservation. Setting an ambitious recovery target for a species requires considering the size, density, and demographic structure of its populations such that they fulfill the interactions, roles, and functions of the species in the ecosystems in which they are embedded. A recently proposed framework for an International Union for Conservation of Nature Green List of Species formalizes this requirement by defining a fully recovered species in terms of representation, viability, and functionality. Defining and quantifying ecological function from the viewpoint of species recovery is challenging in concept and application, but also an opportunity to insert ecological theory into conservation practice. We propose 2 complementary approaches to assessing a species’ ecological functions: confirmation (listing interactions of the species, identifying ecological processes and other species involved in these interactions, and quantifying the extent to which the species contributes to the identified ecological process) and elimination (inferring functionality by ruling out symptoms of reduced functionality, analogous to the red-list approach that focuses on symptoms of reduced viability). Despite the challenges, incorporation of functionality into species recovery planning is possible in most cases and it is essential to a conservation vision that goes beyond preventing extinctions and aims to restore a species to levels beyond what is required for its viability. This vision focuses on conservation and recovery at the species level and sees species as embedded in ecosystems, influencing and being influenced by the processes in those ecosystems. Thus, it connects and integrates conservation at the species and ecosystem levels. 相似文献
87.
David M Lodge Susan Williams Hugh J MacIsaac Keith R Hayes Brian Leung Sarah Reichard Richard N Mack Peter B Moyle Maggie Smith David A Andow James T Carlton Anthony McMichael 《Ecological applications》2006,16(6):2035-2054
The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management. 相似文献
88.
Groundwater management with stochastic surface flows and artificial recharge is considered. Theoretical analysis characterizes the decision rules and establishes conditions for convergence of socially optimal and common property withdrawals and pumping lifts to limiting probability distributions. An empirical application to Kern County, California finds that optimal withdrawals are generally increasing in hydraulic head and decreasing in surface flows; however, nonmonotone behavior is observed in some instances. Artificial recharge is not observed in the limiting distribution due to an interaction of several factors. Optimal management implies relatively small gains over unregulated groundwater use when preferences are risk neutral. 相似文献
89.
90.
Large-Scale Conversion of Forest to Agriculture in the Boreal Plains of Saskatchewan 总被引:1,自引:0,他引:1
Keith A. Hobson †‡ Erin M. Bayne † Steve L. Van Wilgenburg 《Conservation biology》2002,16(6):1530-1541