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781.
DELAYEDREPAIROFDNADAMAGEBYIONIZINGRADIATIONINPEDIATRICSYSTEMICLUPUSERYTHEMATOSUSANDJUVENILERHEUMATOIDD.Mcurdy,L.Q.Tat,WangZhi...  相似文献   
782.
A new transport model for metals (named NOSTRADAMUS) has been developed to predict concentrations and distributions of Cd, Cu, Ni, Pb and Zn in the southern North Sea. NOSTRADAMUS is comprised of components for water, inorganic and organic suspended particulate matter transport; a primary production module contributes to the latter component. Metal exchange between dissolved (water) and total suspended particulate matter (inorganic + organic) phases is driven by distribution coefficients. Transport is based on an existent 2-D vertically integrated model, incorporating a 35 × 35 km grid. NOSTRADAMUS is largely driven by data obtained during the Natural Environment Research Council North Sea Project (NERC NSP). The sensitivity of model predictions to uncertainties in the magnitudes of metal inputs has been tested. Results are reported for a winter period (January 1989) when plankton production was low. Simulated ranges in concentrations in regions influenced by the largest inflows, i.e. the NE English coast and the Southern Bight, are similar to the ranges in the errors of the concentrations estimated at the northern and southern open sea boundaries of the model. Inclusion of uncertainties with respect to atmospheric (up to ± 54%) and riverine (± 30%) inputs makes little difference to the calculated concentrations of both dissolved and particulate fractions within the southern North Sea. When all the errors associated with the inputs are included there is good agreement between computed and observed concentrations, and that for dissolved and particulate Cd, Cu and Zn, and dissolved Ni and Pb, many of the observations fall within, or are close to, the range of values generated by the model. For particulate Pb, model simulations predict concentrations of the right order, but do not reproduce the large scatter in actual concentrations, with simulated concentrations showing a bias towards lower values compared to those observed. A factor which could have contributed to observed concentrations, and which is not included in the model, is considered to be a substantial benthic input of dissolved lead during this winter period, coupled to a rapid and extensive scavenging of the dissolved lead to particles. Significant reductions in riverine and aeolian inputs of total Cd and Cu of 70% and 50%, respectively, consistent with aims of North Sea Conferences, are predicted to lead to minor decreases (~ 10%) in water column concentrations of dissolved and particulate Cd and Cu, except near river sources, where maximum reductions of ~ 30–40% may occur.  相似文献   
783.
784.
Traffic congestion has received considerable public and media attention over the past several years. However, many of the transportation and land use actions offered to deal with the congestion phenomenon focus only on a specific site or at most a subregion of the metropolitan area. This paper argues that congestion in many cases is an areawide phenomenon requiring consideration from a regional and programmatic viewpoint. A ten-point congestion-relief program developed for eastern Massachusetts is described. Actions in this program included those aimed to mitigate current congestion and avoid future congestion through land use management. Four policy areas are emphasized - providing transportation system improvements, managing transportation demand, managing land use, and managing the institutional and funding framework. The paper concludes that because of the political nature of the congestion problem, the congestion-relief program's importance lies more in the message it sends to the public that programmatic action is being taken. The paper also concludes that a regional approach is necessary thus requiring close examination of existing institutions, that demand management is an important component of the strategy, that the private sector has an important role to play, and that the long-term effectiveness of the program relates to the success of attempts to DDLE" BORDER="0">institutionalizeDDLE" BORDER="0"> efforts into zoning and permit procedures.  相似文献   
785.
城市轨道交通换乘枢纽大客流换乘疏散研究   总被引:3,自引:0,他引:3  
从换乘设备设施、换乘乘客特性和运营组织方案3个方面分析了对大客流换乘疏散的影响。最后,以某地铁换乘站为例,针对列车不同的到达时间间隔对换乘疏散的影响进行仿真研究,并对大客流换乘疏散组织提出建议。  相似文献   
786.
汽车部件对污染的敏感性   总被引:1,自引:0,他引:1  
污染敏感性分析是实现对整个机械系统污染控制的重要步骤。通过对污染的分析、测试、建模及模拟分析可有助于减少污染物或微小颗粒对机械系统造成的污染,避免因污染而导致的系统故障。对有关汽车机械系统污染的问题进行了分类讨论并进行了相关性分析,对测试及计算机建模方法进行了论述。给出了污染敏感性分析流程,最后通过几个典型实例阐明了污染敏感性分析的意义。  相似文献   
787.
Net in situ production and export of dissolved organic carbon (DOC) and nitrogen (DON) have been studied in shelf waters off the Ría de Vigo (NW Spain), as part of a comprehensive hydrographic survey carried out from September 1994 to September 1995 with a fortnight periodicity. DOC and DON correlated well (r=+0.78), the slope of the regression line being 12.0±0.7 mol-C mol-N−1, about twice the Redfieldian slope of particulate organic matter, 6.5±0.2 mol-C mol-N−1 (r=+0.95). Labile DOC and DON accumulated in the upper 50 m during the upwelling season (March–September), mainly after prolonged periods of wind relaxation, when horizontal flows were reduced. This labile material represented 50% and 35% of the total (dissolved+particulate) organic carbon and nitrogen susceptible of microbial utilisation, which assert the key contribution of dissolved organic matter (DOM) to the export of new primary production in the NW Iberian upwelling system. This surface excess in shelf waters appeared to be formed into the highly productive Ría de Vigo (a large coastal indentation) at net rates of 4.4 μM-C d−1 and 1.3 μM-C d−1 in the inner and outer segments of the embayment respectively, and subsequently exported to the shelf. Once in the shelf, simple dilution with the inert DOM pool of recently upwelled Eastern North Atlantic Central Water (ENACW) occurred. Eventually, the DOM excess produced during the upwelling season is exported to the adjacent open ocean waters by the coastal circulation. Conversely, during the unproductive downwelling season (October–February), the lowest DOC and DON levels were recorded and export was prevented by the characteristic downwelling front associated to the seasonal poleward slope current.  相似文献   
788.
Road Vehicle Suspension System Design - a review   总被引:8,自引:0,他引:8  
Based mainly on English language literature, information relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed. The information is interpreted in the context of vehicles which travel through a wide speed range on roads of markedly differing quality, which do so carrying different loads and which are required to possess good handling qualities.

Sections are devoted to describing road surfaces, modelling vehicles and setting up performance criteria, and to passive, active, semi-active and slow-active system types. Methods for deriving active system control laws are outlined. Strengths and weaknesses of the various systems are identified and their relative performance capabilities and equipment requirements are discussed. Attention is given to adaptation of the suspension or control system parameters to changing conditions. Remaining research needs are considered.  相似文献   
789.
790.
We used expert elicitation to examine potential responses of eelgrass to several restoration strategies in Puget Sound. Restoration strategies included shoreline armor removal and modification, removal and modification of overwater structures, and efforts to improve water clarity via reductions in anthropogenic nutrient and sediment loadings. Expert responses indicated a general belief that reducing stressors would increase eelgrass cover; however, responses varied greatly among stressors. Our analyses revealed that removal of overwater structures, nutrient loading and shoreline armoring will have significantly larger effects on eelgrass recovery than would removal of sediment loading, with removal of overwater structures having the largest effect. We then used a probabilistic model to estimate what actions, singularly or in combination, could yield a large increase in eelgrass cover. Reducing single stressors could, in theory, result in recovery of eelgrass in Puget Sound; however, the magnitude of actions required would be so great that it is likely not practical. In contrast, we identified combinations of smaller reductions of stressors that could achieve significant eelgrass recovery. For example, a 40% reduction in overwater structures, combined with 20% reductions in shoreline armor, and nutrient and sediment loadings, was predicted to be one of the more feasible combinations of actions for meeting the target. The importance of eelgrass to Puget requires prompt input of scientific advice, and this work fills an important knowledge gap in the face of rapidly approaching legislative deadlines. While coded expert opinion of the sort we use here is a weak substitute for data, our work clarifies the current extent of scientific uncertainty that can guide management action in the near term and scientific research in the long term.  相似文献   
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