Functional imaging method of biological electrical characteristics based on magneto-acoustic effect gives valuable information of tissue in early tumor diagnosis, therein time and frequency characteristics analysis of magneto-acoustic signal is important in image reconstruction. This paper proposes wave summing method based on Green function solution for acoustic source of magneto-acoustic effect. Simulations and analysis under quasi 1D transmission condition are carried out to time and frequency characteristics of magneto-acoustic signal of models with different thickness. Simulation results of magneto-acoustic signal were verified through experiments. Results of the simulation with different thickness showed that time-frequency characteristics of magneto-acoustic signal reflected thickness of sample. Thin sample, which is less than one wavelength of pulse, and thick sample, which is larger than one wavelength, showed different summed waveform and frequency characteristics, due to difference of summing thickness. Experimental results verified theoretical analysis and simulation results. This research has laid a foundation for acoustic source and conductivity reconstruction to the medium with different thickness in magneto-acoustic imaging.
Magnetoacoustic tomography (MAT) has some advantages such as high sensitivity and high spatial resolution. The generating mechanism of acoustic source is the research foundation of forward and inverse problems. Acoustic signals were respectively simulated by using monopole and dipole radiation theory in the experimental conditions, then the differences between their acoustic pressures were discussed, and furthermore the contrast and validation were conducted by physical experiments in this study. The physical experimental results showed that acoustic waveform of MAT had a certain directivity and therefore they indicated that dipole model showed higher approximation to the real facts than monopole model. It can be well concluded that this research has cardinal significance for the accurate algorithm of MAT.
Evolutionary psychology holds such an opinion that negative situation may threaten survival, trigger avoidance motive and have poor effects on the human body function and the psychological quality. Both disgusted and sad situations can induce negative emotions. However, differences between the two situations on attention capture and emotion cognition during the emotion induction are still not well known. Typical disgusted and sad situation images were used in the present study to induce two negative emotions, and 15 young students (7 males and 8 females, aged 27±3) were recruited in the experiments. Electroencephalogram of 32 leads was recorded when the subjects were viewing situation images, and event-related potentials (ERP) of all leads were obtained for future analysis. Paired sample t tests were carried out on two ERP signals separately induced by disgusted and sad situation images to get time quantum with significant statistical differences between the two ERP signals. Root-mean-square deviations of two ERP signals during each time quantum were calculated and the brain topographic map based on root-mean-square deviations was drawn to display differences of two ERP signals in spatial. Results showed that differences of ERP signals induced by disgusted and sad situation images were mainly manifested in T1 (120-450 ms) early and T2 (800-1 000 ms) later. During the period of T1, the occipital lobe reflecting attention capture was activated by both disgusted and sad situation images, but the prefrontal cortex reflecting emotion sense was activated only by disgusted situation images. During the period of T2, the prefrontal cortex was activated by both disgusted and sad situation images. However, the parietal lobe was activated only by disgusted situation images, which showed stronger emotional perception. The research results would have enlightenment to deepen understanding of negative emotions and to explore deep cognitive neuroscience mechanisms of negative emotion induction.
ObjectiveTo investigate the indications and clinical effect of pancreatoduodenectomy with extended lymphadenectomy for pancreatic head carcinoma. MethodsThe clinical data of 21 patients with pancreatic head carcinoma that performed pancreatoduodenectomy with extended lymphadenectomy between June 2010 to June 2011 in Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology were retrospective analyzed. The 21 patients included 15 men and 6 women with an age range of 36-57 years and an average age of 47.8 years. ResultsThere were 3 cases(14.3%), 9 cases(42.9%), 8 cases(38.1%), and 1 case(4.8%) in stageⅠ, ⅡA, ⅡB, andⅢ, respectively. Eighteen cases had a R0 resection(85.7%) and 3 cases had a R1 resection. The total number of resected lymph nodes were 14-43 with an average of 27.4. Lymph node invasion occurred in 10 cases(47.6%). The average operative time was 6.8 h(5-8.5 h) and the average amount of blood transfusion was 5.6 U(3-8 U). There was no death in this group and 5 cases(23.8%) had postoperative complications. Tree cases(14.3%) developed pancreatic fistula, 1 case(4.8%) developed bile leakage, 1 case(4.8%) developed abdominal hemorrhage, 1 case(4.8%) developed gastrointestinal bleeding, and 2 cases(9.5%) developed intractable diarrhea. Postoperative pathological results in high, medium, and low differentiated adenocarcinoma was 6 cases(28.6%), 10 cases(47.6%), and 5 cases(23.8%), respec-tively. Twenty one cases were followed-up, the follow-up time ranged from 5 to 40 months with a median time of 19 months. 1-, 2-, and 3-year cumulative survival rates was 66.7%, 38.1%, and 19%, respectively. ConclusionSelective application of pancreatoduodenectomy with extended lymphadenectomy in resectable pancreatic head carcinoma is conducive to increase the proportion of the radical resection and improve the prognosis, but the postoperative complications is higher.