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SJ McPherson RN Gibson NA Collier TG Speer ND Sherson 《Canadian Metallurgical Quarterly》1998,206(3):665-672
Ancylostoma duodenale is still the dominant hookworm species in the Mediterranean area, India, China and Japan. In the present study, biopsied materials were taken from the small intestine of 30 patients infected only with A. duodenale and 12 cross matched controls. The results showed some pathological changes in severely infected cases. However, normal or insignificant changes were seen in the enzymatic activity of the intestinal mucosa. 相似文献
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正事实上,绝大多数攻击者是经由用户及其设备进入企业的。现实情况往往是黑客跟踪一个用户,然后此用户成为帮助黑客到达数据库或用户凭据的一个管道。因此,企业不仅需要端点安全和网络安全,而且还要将不同的安全方案集成起来。安全厂商也应当听从时代的召唤,建设针对新威胁的安全方案,迎接深度安全的新时代。 相似文献
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Hair, muscle, and liver mercury concentrations were determined in river otter (Lutra canadensis) carcasses collected from the lower coastal plain and piedmont of Georgia. Mean muscle and hair mercury concentrations were greater (P < 0.001) in otters from the lower coastal plain (4.42 and 24.25 mg/kg wet wt, respectively) compared to otters from the piedmont (1.48 and 15.24 mg/kg, respectively). Liver tissue from lower coastal plain otters averaged 7.53 mg/kg mercury. Mean fetus brain and muscle mercury concentrations were 1.03 and 1.58 mg/kg wet wt, respectively, and fetal muscle mercury concentrations were correlated (r = 0.92) with maternal muscle mercury concentrations. Comparison of mercury concentrations found in Georgia otters to those associated with adverse effects in otter and mink (Mustela vison), indicate sublethal contamination with concentrations in some individuals approaching that observed in experimentally dosed individuals that developed clinical signs of mercurialism. Mercury concentrations in fish from the lower coastal plain approached or exceeded concentrations demonstrated to be toxic to experimentally dosed otters. 相似文献
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We consider the issue of bandwidth partitioning in a multi-rate broadband network. Requests for a number of different types of connection are offered to the network. For the purposes of connection admission and resource allocation, we assume that it is possible to allocate an effective bandwidth to a single connection of each type. The network manager has the problem of implementing an admission control scheme to maximise the profit earned from the network. Our focus here is the extent to which it is a good idea to partition the bandwidth on the physical links to form reserved end-to-end logical links corresponding to the origin–destination pairs. It is clear that implementation of such partitioning will lead to a loss of multiplexing opportunities. However, in a network with end-to-end logical links, costs related to overhead such as route selection, admission control and signalling may be much reduced. This effect may outweigh the loss of revenue due to missing out on multiplexing opportunities. We investigate the nature of this trade-off, by designing optimal or near-optimal partitioned networks using efficient algorithms for finding routes and allocating bandwidth to end-to-end logical links on a fixed underlying physical network. We then calculate the net rate of earning profit under each of the schemes as a function of the ratio of overhead costs to call revenue. Our conclusion is that it is cost-effective to partition bandwidth under a variety of realistic assumptions about revenue rates and overhead costs. 相似文献
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Reflectance pulse oximetry measurements from the retinal fundus 总被引:1,自引:0,他引:1
de Kock J.P. Tarassenko L. Glynn C.J. Hill A.R. 《IEEE transactions on bio-medical engineering》1993,40(8):817-823
Conventional transmission pulse oximetry is a noninvasive technique for the continuous monitoring of arterial oxygen saturation (SaO2) from peripheral vascular beds such as the finger tip or earlobe. It is proposed to exploit the unique transparency of the ocular media to make reflectance pulse oximetry measurements on the retinal fundus. This technique potentially offers significant advantages over conventional pulse oximetry, primarily in the ability to monitor cerebral, as opposed to peripheral, oxygen saturation. An in vitro system has been developed to simulate the retinal circulation and ocular optics. This system consists of a flexible cuvette located in a model eye and an extracorporeal blood circuit to simulate arterial blood flow. The system was used to investigate the relationship between SaO2 and the R/IR ratio in reflectance pulse oximetry. To enable in vivo measurements to be made, a standard haptic contact lens was modified to hold the pulse oximeter probe in front of the pupil. In a preliminary study, the lens was fitted to an awake volunteer and cardiac-synchronous signals were detected by the retinal pulse oximeter 相似文献