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排序方式: 共有243条查询结果,搜索用时 15 毫秒
1.
J Byrne S Kienzle D Johnson G Duke V Gannon B Selinger J Thomas 《Water science and technology》2006,53(10):327-334
Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased waterborne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from waterholding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies. 相似文献
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Antisera towards neurotensin (NT) and the structurally related peptide, LANT6, were used to characterize immunoreactive peptides and proteins in extracts of chicken tissues. A 17 kDa protein was identified by Western blotting as a potential precursor to NT and LANT6. However, the posttranslational processing of this common precursor appeared to be tissue specific, giving rise to disproportionate amounts of NT and LANT6, along with varying expression of a large molecular LANT6 (M(r), 15 kDa). The intestinal cells containing immunoreactive NT, LANT6, and large molecular LANT6 behaved similarly during fractionation by size and density. These activities also banded together in particles resembling vesicles during centrifugation of isotonic homogenates of tissue. These results suggest that chicken NT and LANT6 are biosynthesized as parts of the same precursor, the processing of which can give rise to a variety of products stored within secretory vesicles. 相似文献
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David Duke 《Network Security》2003,2003(2):4-8
Anti-virus (AV) products and other fingerprint-based systems are typical of the applications used to enforce security. AV products are probably the first step that most organizations take to protect their systems and enhance security. Many small to medium organizations rely almost entirely on AV products. 相似文献
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Tony L. Schmitz Jeremiah Couey Eric Marsh Nathan Mauntler Duke Hughes 《International Journal of Machine Tools and Manufacture》2007,47(5):841-851
This paper investigates the effect of milling cutter teeth runout on surface topography, surface location error, and stability in end milling. Runout remains an important issue in machining because commercially-available cutter bodies often exhibit significant variation in the teeth/insert radial locations; therefore, the chip load on the individual cutting teeth varies periodically. This varying chip load influences the machining process and can lead to premature failure of the cutting edges. The effect of runout on cutting force and surface finish for proportional and non-proportional tooth spacing is isolated here by completing experiments on a precision milling machine with 0.1 μm positioning repeatability and 0.02 μm spindle error motion. Experimental tests are completed with different amounts of radial runout and the results are compared with a comprehensive time-domain simulation. After verification, the simulation is used to explore the relationships between runout, surface finish, stability, and surface location error. A new instability that occurs when harmonics of the runout frequency coincide with the dominant system natural frequency is identified. 相似文献
9.
Binding Virtual Environments to Toolkit Capabilities 总被引:1,自引:0,他引:1
There are many toolkits and development environments that aid the process of constructing virtual environment applications. Many of these development environments encourage customising a virtual environment's design while rapid prototyping within the confines of a toolkit's capabilities. Thus the choice of the technology and its associated support has been made independent of the end-use requirements of the final system. This can bias a virtual environment's design by implementation based constraints. We propose that an alternative approach is the consideration of virtual environment requirements in the context of an inspectable design model, to identify the requirements that a toolkit will need to support. In the context of an example, we present a selection of design requirements that we consider important for virtual environment design in general. We explore how these requirements might be mapped to different capabilities using Virtual Reality Modelling Language (VRML) as a concrete example of a platform technology. 相似文献
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Duke JR 《Computers in healthcare》1991,12(6):47-48
Evaluating hospital information systems has taken a variety of forms since the initial development and use of automation. The process itself has moved from a hardware-based orientation controlled by data processing professionals to systems solutions and a user-driven process overseen by management. At Harbor Hospital Center in Baltimore, a fast track methodology has been introduced to shorten system evaluation time to meet the rapid changes that constantly affect the healthcare industry. 相似文献