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991.
A modelling study with the on-line coupled Eulerian chemical-weather model WRF/Chem for the Southern Italian region around Cosenza (Calabria) was conducted to identify the influences of synoptic scale meteorology, local scale wind systems and local emissions on ozone concentrations in this orographically complex region. Four periods of 5–7 days were chosen, one from each season, which had wind pattern characteristics representative of typical local climatological conditions, in order to study the local versus non-local impacts on ozone transport and formation. To account for the complex terrain, the horizontal resolution of the smallest modelling domain was 3 km. Model results were compared with measurements to demonstrate the capability of the model to reproduce ozone concentrations in the region. The comparison was favourable with a mean bias of ?1.1 ppb. The importance of local emissions on ozone formation and destruction was identified with the use of three different emission scenarios. Generally the influence of regional emissions on the average ozone concentration was small. However during periods when mountain-sea wind systems were well developed and synoptic scale winds were weak, the influence of local emissions from the urban area was at its greatest. The maximum influence of local emissions on ozone concentrations was 18 ppb.  相似文献   
992.
We conducted playback experiments to examine how parent tree swallows (Tachycineta bicolor) use nestling begging calls to distribute feedings to individuals within broods. In a first study, we used a paired-choice test to determine if parents discriminated between the taped begging calls of nestlings deprived of food and those of nestlings that had been recently fed. Our results showed that parents directed their first feeding attempt towards model nestlings near speakers playing deprived calls significantly more often than to models near speakers playing fed calls. They also made more feeding attempts overall to models with deprived calls. In the second study, we varied call rate and amplitude to examine which call features parents might use to discriminate begging calls. Parents directed significantly more first feeding attempts and more feeding attempts overall towards non-begging nestlings near speakers playing high call rates than to nestlings near speakers playing low call rates. They did not, however, discriminate between calls differing in amplitude. Previous studies have shown that parent birds use begging calls to regulate overall feeding rates to the brood. Our results suggest that parent tree swallows also use begging calls when feeding individual nestlings and, in particular, prefer calls associated with increased levels of nestling hunger. Received: 14 February 2000 / Revised: 6 October 2000 / Accepted: 16 October 2000  相似文献   
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本文描述中国、印度、菲律宾和斯里兰卡能源密集和污染型工业中可以引进的一些技术变革.当选择一种新的高能效和环境无害的工业技术时需要考虑的因素中包括现行技术的状态、前期费用、运行费用、设备效率、企业内部可供利用的技能水平.为了确认一种新技术是经济上可行的,也需要考虑许多外部因素:合理能源定价的存在,是否有适用的环境法规和激励机制到位,总体金融环境,经济体系的透明度等.  相似文献   
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The purpose of this review was to summarize the literature on occupational, acute, traumatic hand injury and suggest directions for future research. In 1996, the leading occupational injury treated in United States' hospital emergency departments was an acute hand injury (e.g. laceration, crush or fracture). These injuries affected 30% of an estimated 3.3 million injured workers (990,000). Cuts and lacerations of the fingers ranked third after back and leg strains in the number of lost workday cases in the USA in 1994. The incidence rate of hand injuries studied in seven manufacturing environments around the world ranged from 4 to 11 per 100 workers per year. Workers aged 24 years or less had the highest risk of hand injury. Men had higher rates of severe hand injury than women.Despite the high frequency and significant amount of lost work time associated with these injuries, they are poorly understood from an etiological perspective. There is only one case-control study of occupational hand injury in the literature. That study suggested an important role for both fixed (age) and transient risk factors (doing an unusual task) at the time of the injury. More analytic epidemiological research is needed to identify potentially modifiable risk or protective factors (e.g. glove use) for acute hand injuries. In this regard, the case-crossover design, a relatively new epidemiological approach using cases as their own controls, could prove an efficient method for determining transient, modifiable risk factors for acute, occupational hand injury.  相似文献   
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