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A method for generating olfactory stimuli for humans within a functional magnetic resonance imaging (fMRI) experimental design is described. The system incorporates a nasal-mask in which the change from odorant to no-odorant conditions occurs in less than 500 ms and is not accompanied by visual, auditory, tactile, or thermal cues. The mask provides an ordorant-free environment following prolonged ordorant presence. Specific imaging parameters that are conducive to the study of the human olfactory system are described. In a pilot study performed using these methods, the specific patterns of activation observed converged with published experimental and clinical findings.  相似文献   
3.
刘昭  黄令仪  曾烈光 《微电子学》2002,32(2):105-108,112
文章提出了一种硬布线逻辑CPU的设计流程,即以CPU设计工具软件LDF为核心的设计方法,其主要目的的提高硬布线逻辑CPU的设计效率。定义了一种用于描述硬布线控制逻辑的语言-MCDL,对总线优化问题进行了研究,并且给出了解决总线优化问题的近似算法。  相似文献   
4.
在国内首次应用模型水轮发电机组对三峡地下电站变顶高尾水洞方案进行水力过渡过程试验研究。对水轮机导叶实行分段关闭 ,并求出了二段关闭的最佳拐点 ,试验证实了二段关闭对减小尾水管进口的负压和机组转速上升有明显的作用。通过有关水力参数的测试 ,认为变顶高尾水洞可以满足各项技术要求 ,是一个减少山体开挖、节省投资的新型设计方案。在地下电站中具有广泛的应用前景  相似文献   
5.
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
6.
对分置式牛津型斯特林制冷机进行了数值计算 ,介绍了计算模型考虑到的众多不可逆因素。通过对计算结果与实验结果的对比 ,验证了本文数值计算的准确性 ,说明本文计算模型与数值处理方法是切实可行的  相似文献   
7.
The Analysis Committee of the European Brewery Convention is aware that the Friabilimeter sometimes is used on samples that do not comply with the field of application. The precision of the method is also overlooked by some users. The field of application, precision of the method as well as the need for frequent testing of the instrument is therefore stressed in more detail than in the earlier published method by the EBC Analysis Committee.  相似文献   
8.
Case reports from the United Kingdom (UK) in 1989 have suggested that the introduction of human insulin in 1985 was associated with an increased risk of sudden death in insulin-treated diabetic patients. If human insulin increases the risk of sudden death, the number of these should have increased during the period where human insulin was introduced. We therefore identified all cases of sudden death in Denmark in younger insulin-treated diabetic patients, age at death below 50 years. During this period the consumption of human insulin went from 0.2% to 70% of the total consumption in Denmark. The total number of cases fulfilling the inclusion criteria was 226, and the annual number of sudden deaths did not change during the study period (p = 0.14). The number of deaths due to hypoglycaemia and cases with unexplained cause of death also remained constant (test for trend: p = 0.44). Chronic alcohol abuse or acute alcohol intoxication was found in 50% of the 135 patients dying from hypoglycaemia, ketoacidosis or unknown cause of death (including found dead in bed), while this was the case in only 16% of the remaining 91 cases dying from other natural causes. We conclude that introduction of human insulin in Denmark was not followed by an increase in sudden deaths among younger insulin-treated diabetic patients.  相似文献   
9.
The frequency of human papillomavirus (HPV) in laryngeal papillomas varies largely among different studies. DNA in situ hybridization (ISH) has been the most widely used method for detection of HPV. The aim of this study was to compare the reproducibility and sensitivity of ISH with polymerase chain reaction (PCR) in 35 specimens of laryngeal papillomas routinely fixed in buffered or unbuffered formalin. Out of 12 specimens fixed in buffered formalin, 10 were positive for HPV 6/11 using ISH. The procedure was repeated three times and three specimens were positive only twice. Nine biopsies were positive for HPV using PCR with consensus primers (My 09/11) on dewaxed tissue without extracting DNA. In three repeated PCRs, the results were inconsistent in three samples. After DNA extraction, all 12 samples were positive with PCR. Of the 23 specimens fixed in unbuffered formalin, 14 were HPV-positive with ISH, while only one was positive with PCR. We concluded that PCR with My 09/11 consensus primers is a highly sensitive method for detection of HPV in laryngeal papillomas fixed in buffered formalin, but useless for samples fixed in unbuffered formalin. When DNA was extracted from the former type of fixed tissue, the results were highly reproducible. In contrast to PCR, ISH appeared to be less influenced by fixation procedure, but it was not as reproducible and sensitive as PCR. Negative results did not necessarily mean absence of HPV.  相似文献   
10.
ATM-PON是光纤接入网的重要技术。文章研究了业务穿越ATM-PON接入网的延时和延时变化性能,着重分析媒体接入控制协议对业务延时和延时变化性能的影响。研究结论对ATM-PON媒体接入控制协议的合理设计有很大的帮助。  相似文献   
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