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91.
92.
Previous findings suggested that banner ads have little or no impact on perceptual behavior and memory performance in search tasks, but only in browsing paradigms. This assumption is not supported by the present eye-tracking study. It investigates whether task-related selective attention is disrupted depending on the animation intensity of banner ads when users are in a search mode as well as the impact of banner animation on perceptual and memory performance.  相似文献   
93.
Arsenic is a natural tasteless and odourless element,existing in the earth’s crust at average levels of between two and five thousands micrograms per liter (parts per million) . Arsenic is highly toxic to humans, who are exposed to it primarily from air,food and water. The occurrence of arsenic in groundwater is due to geological composition of soil. High concentrations of arsenic in water are the result of dissolution or desorption of ferric oxides and the oxidation of mineral arsenopyrites. Arsenic in drinking water has an important impact on the human health,especially in the less developed countries. Different methods exist to remove arsenic from aquatic media,and one of them is by adsorption. In this work,the adsorption of both As(III) and As(V) by means of novel microspheres has been investigated. In particular,TiO2 has been embedded into polymeric microspheres PES (PolyEtherSulphone) and PEEK-WC (PolyEtherEther-Ketone) . The main advantages of this encapsulation adsorption material are: no loss of adsorbents into the water stream,easy to be used and scaled-up.  相似文献   
94.
Enteropathogenic, enterotoxigenic and enteroinvasive Escherichia coli were isolated from 52 (4.8%) of 1,082 patients with acute gastroenteritis reporting at the Lagos University Teaching Hospital, Lagos, Nigeria between October 1979 and March, 1981. Of the 52 strains of E. coli isolated, 35 (67.3%) were enteropathogenic, 12 (23.1%) were enterotoxigenic and five (9.6%) were enteroinvasive. E. coli 0111 (25.7%) was the most predominant among the serotypes of the "classical" enteropathogenic strains found in this study. Diarrhoea associated with enteropathogenic E. coli occurred only in children aged less than five years, whereas enterotoxigenic and enteroinvasive E. coli were found primarily in adults. The study has highlighted for the first time the important role that enterotoxigenic and enteroinvasive E. coli strains could play in acute diarrhoeal diseases in Lagos, Nigeria.  相似文献   
95.
A total of 98 colposcopically directed biopsies were obtained from the vagina, cervix, and cervicovaginal ridge (hood) of 80 young women believed to have had intrauterine exposure to stilbestrol (DES). Specific investigation of the patient's medical records corroborated the history of maternal stilbestrol administration in 36 patients (45%), while in the remainder the drug history was regarded as presumptive since medical records were unavailable for review. The findings did not differ significantly in those biopsies taken from patients with confirmed or presumptive drug histories. Histologic evidence of vaginal adenosis was detected in vaginal biopsies from 43 patients. In 30 cases (70%) benign Müllerian-type glandular epithelium was in the superficial vaginal wall, residing on the mucosal surface and/or in the lamina propria. The glandular epithelium predominantly was of endocervical type, but in six instances it resembled endometrial or fallopian tubal epithelium. The glands were accompanied by varying degrees of squamous metaplasia in 22 cases. When extensive the metaplasia produced transformation zones similar to those seen in the normal cervix. Vaginal biopsies of adenosis from the other 13 patients (30%) revealed squamous metaplasia without demonstrable glands due to complete transformation of all antecedent glandular epithelium by squamous metaplasia. Our studies indicate that squamous metaplasia is a component of major importance in the natural history of adenosis and that the concept of adenosis should be broadened to include those examples comprised exclusively of metaplastic epithelium. In such examples metaplasia is identified by the immaturity and poor glycogenation of the squamous cells and their accompanying squamous pegs which often contain residual gland openings or squamous "eddies." Similar findings were present in biopsies of seven cervicovaginal ridges and in cervical biopsies from 37 patients, except for the absence of endometrial or tubal type glands in the latter site. Although no adenocarcinomas were detected, six patients had squamous dysplasia of the vagina and/or cervix. In no case were premalignant or dysplastic changes of glandular cells found. Our findings support the thesis that stilbestrol-associated adenosis represents anomalous embryologic localization of the original squamocolumnar junction in the vagina rather than in the cervix. It is closely related to so-called cervical "erosions." The development of squamous metaplasia accounts for modifications in the clinical and histologic appearances by producing transformation zones which then may be subject to the same oncogenic stimuli for squamous neoplasia as are their counterparts in the cervix.  相似文献   
96.
97.
We introduce a new concept for a tapered transition between waveguides and a free propagation region (FPR) for rib waveguide technology. The optical field is pressed downwards to the lower part of the guiding layer by tapering off the waveguide. The subsequent FPR is also etched down to the lower part of the guiding layer, which results in an adiabatic transition from the waveguide to the slab. Arrayed waveguide gratings, designed with this technique, were fabricated in silicon-on-insulator and showed a reduction in insertion loss of about 2.5 dB  相似文献   
98.
The points-to analysis problem is to find the pointer relationships that could arise during program execution. Many points-to analysis algorithms exist, each making a particular trade off between cost of the analysis and precision of the results. In this paper, we show how points-to analysis algorithms can be defined as transformed versions of an exact algorithm. We present a set of program transformations over a general program model and use them to define some existing points-to analysis algorithms. Doing so makes explicit the approximations involved in these algorithms. We also show how the transformations can be used to define new points-to analysis algorithms. Our transformations are generic and may be useful in the design of other program analysis algorithms.  相似文献   
99.
高速铁路铰接式列车车桥系统动力响应分析   总被引:5,自引:0,他引:5  
根据铰接式车辆结构和悬挂形式的特点,建立了铰接车辆单元模型,以现有通用软件为基础直接生成桥梁模型的质量、刚度矩阵,并以实测轨道不平顺为系统激励,求解车桥耦合动力相互作用问题;以欧洲布鲁塞尔-巴黎高速铁路线上的Thalys铰接式列车通过Antoing桥为例,分析了桥梁的动挠度、竖向和横向加速度等动力响应及运行车辆的振动加速度响应,并对铰接式列车的振动特性进行了初步的探讨;最后通过现场试验对分析模型和计算结果进行了验证。  相似文献   
100.
In this paper multi-stage flow lines with intermediate buffers are approximated by two-stage lines by using repeated aggregation. The aggregation method uses restricted information of the output pattern of two-stage lines. The method is tested for the case where all production units are unreliable with exponential life-and repair-times. It appears that it performs well for most cases, provided we aggregate in the correct sequence.  相似文献   
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