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511.
Burfield IJ 《Ambio》2008,37(6):401-407
To conserve biodiversity efficiently, an international framework is needed to ensure that national priorities take into account regional and global priorities. BirdLife International has published five comprehensive assessments of the global status of the world's birds and two evaluations of the status of Europe's birds at a continental level. This paper analyzes the results of these assessments in relation to Europe's 56 species of raptors and owls, 18% of which are of global conservation concern, and 64% of which have an unfavorable conservation status in Europe. The European Union (EU) holds half of the total estimated European breeding population of raptors and owls, and European Russia supports another third, but every European country has a responsibility for at least two species of European conservation concern. During the 1990s, more raptors increased than decreased in most EU member states, but the opposite was true in eastern Europe, where many of the most threatened species are concentrated. Given the popularity of these species with the public, and the political commitment to halt the loss of biodiversity by 2010, much more action is needed to monitor and conserve birds of prey.  相似文献   
512.
We assess the implications which research on endocrine disrupting chemicals (EDCs) has for the regulation of synthetic substances and for the protection of the environment, particularly under the forthcoming European Union (EU) REACH legislation. EDCs present regulatory problems inter alia because they can act additively at concentrations which are individually harmless, and they may have non-classical dose (concentration)-response relationships at low exposure levels. Furthermore, current in vivo testing routines were not specifically designed to assess the endocrine disrupting properties of chemicals, whilst in silico and in vitro methods have only limited applicability and availability for this purpose. We need to ensure that the assessment approaches specified in the draft REACH legislation and Technical Guidance are able to evaluate EDCs efficiently. However, it must also be recognised that environmental monitoring procedures in Europe will need to be improved to detect EDCs that have evaded identification, and where appropriate, control, under REACH.  相似文献   
513.
Sulfur is an extremely motile and vital element in the Earth's biogeochemical environment, one whose active redox chemistry maintains small reservoirs in the atmosphere and biosphere yet large fluxes through both. Essential for life, intimately linked to the climate state, and an important component of air quality, sulfur and its transport and processing in the atmosphere have been the subject of active research for several decades. This review article describes the current state of our understanding of the atmospheric sulfur cycle, focusing on the marine atmospheric boundary layer, with the aim of identifying the largest roots of uncertainty that most inhibit accurate simulation of sulfur cycling in the atmosphere. An overview of the emissions by phytoplankton and shipping, dispersion and entrainment in the marine boundary layer, and chemical processing by aerosols, clouds, and dry deposition is presented. Analysis of 20 contemporary modeling studies suggests that the greatest ambiguity in global sulfur cycling derives from (in descending order) wet deposition of aerosol sulfate, dry deposition of sulfur dioxide to the Earth's surface, and the heterogeneous oxidation of SO2 in aerosols and clouds.  相似文献   
514.
A study has been conducted in Launceston, Australia, to determine within households with wood heaters the effect of leakage from the heater and flue on the indoor air concentrations of the pollutants: benzene, toluene, ethylbenzene and xylene (BTEX). The study involved three classes: 28 households without wood heaters, 19 households with wood heaters compliant with the relevant Australian Standard and 30 households with non-compliant wood heaters. Outdoor and indoor BTEX concentrations were measured in each household for 7 days during summer when there was little or no wood heater usage, and for 7 days during winter when there was widespread wood heater usage. Each participant kept a household activity diary throughout their sampling periods. For wintertime, there were no significant differences of the indoor BTEX concentrations between the three classes of households. Also there were no significant relationships between BTEX indoor concentrations within houses and several measures of the amount of wood heater use within these houses. For the households sampled in this study, the use of a wood heater within a house did not lead to BTEX release within that house and had no direct detectable influence on the concentrations of BTEX within the house. We propose that the pressure differences associated with the both the leakiness or permeability of the building envelope and the draught of the wood heater have key roles in determining whether there will be backflow of smoke from the wood heater into the house. For a leaky house with a well maintained wood heater there should be no backflow of smoke from the wood heater into the house. However backflow of smoke may occur in well sealed houses.The study also found that wood heater emissions raise the outdoor concentrations of BTEX in winter in Launceston and through the mixing of outdoor air through the building envelopes into the houses, these emissions contribute to increases in the indoor concentrations of BTEX in winter in all houses in Launceston.  相似文献   
515.
Most investigations of organizational commitment have been conducted using self‐report measures, however, the veracity of self‐reports is often questioned. In a sample of 79 public‐sector administrative staff, we assessed two types of organizational commitment (affective and continuance) from the perspective of three different sources of raters (self, peer, and supervisor) to test three explanations of the factors influencing self‐report measures (observational opportunities, simple defensiveness, and moderated defensiveness). The pattern of correlations among the measures, analysed using the composite direct product multitrait–multirater approach, suggested that self‐report commitment measures are affected mainly by observations or experiences of the self‐reporter rather than by systematic bias related to defensive responding. This increases our confidence that scores from self‐report measures of affective and continuance commitment are veridical. Further, self‐ and peer‐based measures of commitment were largely redundant in the prediction of a job‐performance criterion whereas supervisory measures added unique predictive variance. Implications are discussed. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
516.
517.
In this research study, biodiesel has been successfully produced from vegetable seed oil of an indigenous plant Salvadora persica L. that meets the international biodiesel standard (ASTM D6751). The biodiesel yield was 1.57 g/5 g (31.4% by weight) and the in-situ transesterification ester content conversion was 97.7%. The produced biodiesel density was 0.894 g/mL, its kinematic viscosity 5.51 mm2/s, HHV 35.26 MJ/kg, flash point 210°C, cetane no. 61, and sulfur content 0.0844%. Thermal analysis of the biodiesel showed that 97% weight loss was achieved at 595°C with total oxidation of the biodiesel. The production energy efficiency was 0.46% with a lab scale setup, assuming the volume fraction ratio (volume of the sample/total volume of the equipment used). The results revealed that single-step in-situ transesterification method is suitable for the production of biodiesel from S. persica seed oil.  相似文献   
518.
We present four reconstruction estimates of Arkansas River baseflow and streamflow using a total of 78 tree-ring chronologies for three streamflow gages, geographically spanning the headwaters in Colorado to near the confluence of the Arkansas-Mississippi rivers. The estimates represent different seasonal windows, which are dictated by the shared limiting forcing of precipitation on seasonal tree growth and soil moisture—and subsequently on the variability of Arkansas River discharge. Flow extremes that were higher and lower than what has been observed in the instrumental era are recorded in each of the four reconstructions. Years of concurrent, cross-basin (all sites) low flow appear more frequently during the 20th and 21st Centuries compared to any period since 1600 A.D., however, no significant trend in cross-basin low flow is observed. As the most downstream major tributary of the Mississippi River, the Arkansas River directly influences flood risk in the Lower Mississippi River Valley. Estimates of extreme high flow in downstream reconstructions coincide with specific years of historic flooding documented in New Orleans, Louisiana, just upstream of the Mississippi River Delta. By deduction, Mississippi River flooding in years of low Arkansas River flow imply exceptional flooding contributions from the Upper Mississippi River catchments.  相似文献   
519.
This study examined whether an employee's level of absenteeism was affected by age, organizational tenure, perceptions of interactional justice, affective and continuance commitment, and the perceived absence norm in the employees' work unit or department. One hundred and sixty-six nursing and food services employees in a mid-size chronic care hospital provided attitudinal and perceptual data on an employee survey. Absence data (absence frequency and total days absent) were collected during the 12-month period immediately following an employee survey. Hypothesized relations between the various individual- and group-level factors and employee absenteeism were specified in a structural model and tested using LISREL 7 (Joreskog and Sorbom, 1989). General support was found for the study hypotheses.  相似文献   
520.
BACKGROUND: Methods to study driving patterns and exposure of older drivers have typically relied on surveys or driving diaries. Electronic data logging devices may offer a reliable, alternative method of measuring driving exposure, and global positioning system (GPS) technology may be able to provide further information about driving patterns. OBJECTIVES: The aim of this study was to compare a driving diary with two electronic data logging devices, one of which had GPS capability, in order to identify which method best assesses the driving exposure and habits of older drivers as well as the method most acceptable to study participants. METHOD: In this prospective cohort study we recruited 20 participants aged 70 years or more (mean 78; range 70-85) (15 men and 5 women). The participants' driving patterns were recorded for one week with an electronic data logging device with GPS (FleetPulse), followed by recording for a further week with an electronic data logging device without GPS (CarChip). During both time periods the subjects also completed a standard driving diary. RESULTS: More comprehensive information, including braking and acceleration patterns, duration of driving time, time of day, and maximum speeds, was collected with the electronic devices than with the driving diary. There was excellent correlation between the driving diary data and those obtained with the CarChip (r = 0.9; p < 0.01). The correlation between the driving diary data and the FleetPulse data was moderate (r = 0.56; p = 0.02). The subjects clearly preferred the electronic monitoring devices over the driving diary. GPS data were able to demonstrate driving routes. CONCLUSIONS: Electronic data logging devices are a valid method for recording the driving patterns of older adults. These devices also reduce burden and improve the completeness of data.  相似文献   
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