The design principle of peripheral devices parameters of low noise amplifier is analyzed based on amplifier circuit and S parameter of amplifier chip and impedance matching. The design process of MAX2640-based LNA circuit is studied using ADS simulation software. Signal gain, noise coefficient and impedance matching are considered in design.
Objective:To investigate whether working memory is impaired in patients with subclinical hypothyroidism(SCH) by performing a n-back test,and by using a block designed functional MRI(fMRI).Methods:The study sample consisted of 2 groups: 11 patients with subclinical hypothyroidism aged 18 to 47,and 12 matched euthyroid subjects.fMRI was scanned on a 1.5 T Philips Infinion MR System while they were performing the n-back test.The independent t-test was used to analyze the plasma hormone levels and the performance of n-back test.The load effects of performance accuracy and BOLD response in the n-back task were evaluated with a general linear model(GLM) for repeated measures.Results:There is no difference in the accuracy of 0-back(t-test,t=1.000,P=0.341) and 1-back(t-test,t=0.145,P=0.886) tasks between both groups.But in the 2-back task,the accuracy of SCH group is significantly lower than the control group(t-test,t=2.658,P=0.015).The load effect of the accuracy of n-back task is significant in both groups(GLM,F>6.232,P<0.01).The fMRI showed that a common frontoparietal network,including bilateral middle/inferior frontal gyri(M/IFG),bilateral dorsolateral prefrontal cortex(DLPFC),bilateral premotor areas(Pre MA),the supplementary motor area/anterior cingulated cortex(SMA/ACC) and bilateral parietal areas(PA),was activated by the n-back task in all the subjects.Further quantitative analysis showed that the load effect of blood oxygen level-dependent(BOLD) response appeared in all the five regions of interest(ROIs) in the euthyroid subjects(GLM,F> 3.690,P<0.043).In the pretreatment SCH patients,however,the load effect of BOLD response was only found in the PA and PreMA(GLM,F>4.444,P<0.05),but not in other frontal cortex ROIs(GLM,F<2.6,P>0.145).Conclusion:fMRI revealed the working memory is impaired in patients with SCH,especially in frontal areas.
患者 男，57岁。乙肝病史10年，肝区疼痛、肝功能持续异常6个月。B超及CT检查诊断为原发性肝癌。住院施行介入治疗。
