According to Maxwell electromagnetic field theory and magnetic vector potential integral equation,a mathematical model of LMF(Level Magnetic Field)for EMBR(Electromagnetic brake)was proposed,and the reliable software ...According to Maxwell electromagnetic field theory and magnetic vector potential integral equation,a mathematical model of LMF(Level Magnetic Field)for EMBR(Electromagnetic brake)was proposed,and the reliable software for LMF calculation was developed.The distribution of magnetic flux density given by numerical simulation shows that the magnetic flux density is greater in the magnet and magnetic leakage is observed in the gap.The magnetic flux density is uniform in horizontal plane and a peak is observed in vertical plane.Furthermore,the effects of electromagnetic and structural parameters on magnetic flux density were discussed.The relationship between magnetic flux,electromagnetic parameters and structural parameters is obtained by dimensional analysis,simulation experiment and least square method.展开更多
Hepatic encephalopathy(HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE....Hepatic encephalopathy(HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging(MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight ofthe increasingly important role of blood oxygen level dependent functional MRI.展开更多
Objective Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) was used to study activation signals in the brain cortex evoked by tone stimulation in patients with tinnitus for its poten...Objective Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) was used to study activation signals in the brain cortex evoked by tone stimulation in patients with tinnitus for its potential utility as an objective indicator of tinnitus. Methods BOLD-fMRI examination was conducted in 7 patients with chronic tinnitus and 15 control subjects. The activation signal in the brain cortex was recorded. Results Significant activation was found in temporal lobe in control subjects, with greater signal volume and intensity on the contralateral than ipsilateral auditory cortex (P < 0.01). However, there was no discernable patterns in the anatomical location, volume and intensity of cortical activation signals in patients with chronic tinnitus. Conclusions Patients with chronic tinnitus may have abnormal neural activities in the auditory cortex.展开更多
基金Item Sponsored by National Key Fundamental Research Development Project of China(G1998061510)
文摘According to Maxwell electromagnetic field theory and magnetic vector potential integral equation,a mathematical model of LMF(Level Magnetic Field)for EMBR(Electromagnetic brake)was proposed,and the reliable software for LMF calculation was developed.The distribution of magnetic flux density given by numerical simulation shows that the magnetic flux density is greater in the magnet and magnetic leakage is observed in the gap.The magnetic flux density is uniform in horizontal plane and a peak is observed in vertical plane.Furthermore,the effects of electromagnetic and structural parameters on magnetic flux density were discussed.The relationship between magnetic flux,electromagnetic parameters and structural parameters is obtained by dimensional analysis,simulation experiment and least square method.
基金Supported by Grants from National Natural Science Foundation of China,Nos.30700194,81171313,81322020 and 81230032(to Zhang LJ)Program for New Century Excellent Talents in University,No.NCET-12-0260(to Zhang LJ)
文摘Hepatic encephalopathy(HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging(MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight ofthe increasingly important role of blood oxygen level dependent functional MRI.
文摘Objective Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) was used to study activation signals in the brain cortex evoked by tone stimulation in patients with tinnitus for its potential utility as an objective indicator of tinnitus. Methods BOLD-fMRI examination was conducted in 7 patients with chronic tinnitus and 15 control subjects. The activation signal in the brain cortex was recorded. Results Significant activation was found in temporal lobe in control subjects, with greater signal volume and intensity on the contralateral than ipsilateral auditory cortex (P < 0.01). However, there was no discernable patterns in the anatomical location, volume and intensity of cortical activation signals in patients with chronic tinnitus. Conclusions Patients with chronic tinnitus may have abnormal neural activities in the auditory cortex.
