By combining magnetics, acoustics and electrics, the magneto-acoustic-electrical tomography（MAET） proves to possess the capability of differentiating electrical impedance variation and thus improving the spatial res...By combining magnetics, acoustics and electrics, the magneto-acoustic-electrical tomography（MAET） proves to possess the capability of differentiating electrical impedance variation and thus improving the spatial resolution. However,the signal-to-noise ratio（SNR） of the collected MAET signal is still unsatisfactory for biological tissues with low-level electrical conductivity. In this study, the formula of MAET measurement with sinusoid-Barker coded excitation is derived and simplified for a planar piston transducer. Numerical simulations are conducted for a four-layered gel phantom with the 13-bit sinusoid-Barker coded excitation, and the performances of wave packet recovery with side-lobe suppression are improved by using the mismatched compression filter, which is also demonstrated by experimentally measuring a three-layered gel phantom. It is demonstrated that comparing with the single-cycle sinusoidal excitation, the amplitude of the driving signal can be reduced greatly with an SNR enhancement of 10 dB using the 13-bit sinusoid-Barker coded excitation. The amplitude and polarity of the wave packet filtered from the collected MAET signal can be used to achieve the conductivity derivative at the tissue boundary. In this study, we apply the sinusoid-Barker coded modulation method and the mismatched suppression scheme to MAET measurement to ensure the safety for biological tissues with improved SNR and spatial resolution, and suggest the potential applications in biomedical imaging.展开更多
正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)是目前为止最有前景的调制技术,已经被大多数无线和有线通信标准采用。N-coutinuous正交频分复用是OFDM与认知无线电技术相结合转换而来的,但它的旁瓣抑制一直是一个需...正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)是目前为止最有前景的调制技术,已经被大多数无线和有线通信标准采用。N-coutinuous正交频分复用是OFDM与认知无线电技术相结合转换而来的,但它的旁瓣抑制一直是一个需要解决的问题。为在不影响旁瓣抑制性能的基础上降低算法和接收机的复杂性,文中提出了一种符号填充正交频分复用的时域算法,将n-连续OFDM校正符号只插入到保护间隔中,并将每个OFDM符号无缝连接起来,从而抑制了旁瓣。仿真结果表明,所提算法不影响旁瓣抑制性能,且易于实现,复杂度相比传统N-continuous正交频分复用系统有了明显降低。在K=72的不同信道,信号的误码率降低5 dB。文中还用matlab的simulink来模拟现场可编程门阵列(Field-Programmable Gate Array,FPGA)的N-coutinuous正交频分复用系统的仿真。FPGA具有很大的灵活性,在数字信号处理上具有更快的计算速度和较小的面积,其成本低,风险小,时间上亦具有优势。展开更多
AIM:To determine predictors of long term survival after resection of hilar cholangiocarcinoma(HC) by comparing patients surviving > 5 years with those who survived < 5 years.METHODS:This is a retrospective study...AIM:To determine predictors of long term survival after resection of hilar cholangiocarcinoma(HC) by comparing patients surviving > 5 years with those who survived < 5 years.METHODS:This is a retrospective study of patients with pathologically proven HC who underwent surgical resection at the Gastroenterology Surgical Center,Mansoura University,Egypt between January 2002 and April 2013.All data of the patients were collected from the medical records.patients were divided into two groups according to their survival:patients surviving less than 5 years and those who survived > 5 years.RESULTS:There were 34(14%) long term survivors(5 year survivors) among the 243 patients.Fiveyear survivors were younger at diagnosis than those surviving less than 5 years(mean age,50.47 ± 4.45 vs 54.59 ± 4.98,p = 0.001).Gender,clinical presentation,preoperative drainage,preoperative serum bilirubin,albumin and serum glutamic-pyruvic transaminase were similar between the two groups.The level of CA 19-9 was significantly higher in patients surviving < 5 years(395.71 ± 31.43 vs 254.06 ± 42.19,p = 0.0001).Univariate analysis demonstrated nine variables to be significantly associated with survival > 5 year,includingyoung age(p = 0.001),serum CA19-9(p = 0.0001),non-cirrhotic liver(p = 0.02),major hepatic resection(p = 0.001),caudate lobe resection(p = 0.006),well differentiated tumour(p = 0.03),lymph node status(0.008),R0 resection margin(p = 0.0001) and early postoperative liver cell failure(p = 0.02).CONCLUSION:Liver status,resection of caudate lobe,lymph node status,R0 resection and CA19-9 were demonstrated to be independent risk factors for long term survival.展开更多
The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of impro...The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of improved Support Vector Machine based on 1-norm(1-SVM) is provided from the optimization problem, yet it is a discrete programming. With the smoothing technique and optimality knowledge, the discrete programming is changed into a continuous programming. Experimental results show that the algorithm is easy to implement and this method can select and suppress the problem features more efficiently. Illustrative examples show that the 1-SVM deal with the linear or nonlinear classification well.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474166 and 11604156)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161013)+2 种基金the Postdoctoral Science Foundation of China(Grant No.2016M591874)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX17 1083)the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions,China
文摘By combining magnetics, acoustics and electrics, the magneto-acoustic-electrical tomography（MAET） proves to possess the capability of differentiating electrical impedance variation and thus improving the spatial resolution. However,the signal-to-noise ratio（SNR） of the collected MAET signal is still unsatisfactory for biological tissues with low-level electrical conductivity. In this study, the formula of MAET measurement with sinusoid-Barker coded excitation is derived and simplified for a planar piston transducer. Numerical simulations are conducted for a four-layered gel phantom with the 13-bit sinusoid-Barker coded excitation, and the performances of wave packet recovery with side-lobe suppression are improved by using the mismatched compression filter, which is also demonstrated by experimentally measuring a three-layered gel phantom. It is demonstrated that comparing with the single-cycle sinusoidal excitation, the amplitude of the driving signal can be reduced greatly with an SNR enhancement of 10 dB using the 13-bit sinusoid-Barker coded excitation. The amplitude and polarity of the wave packet filtered from the collected MAET signal can be used to achieve the conductivity derivative at the tissue boundary. In this study, we apply the sinusoid-Barker coded modulation method and the mismatched suppression scheme to MAET measurement to ensure the safety for biological tissues with improved SNR and spatial resolution, and suggest the potential applications in biomedical imaging.
文摘AIM:To determine predictors of long term survival after resection of hilar cholangiocarcinoma(HC) by comparing patients surviving > 5 years with those who survived < 5 years.METHODS:This is a retrospective study of patients with pathologically proven HC who underwent surgical resection at the Gastroenterology Surgical Center,Mansoura University,Egypt between January 2002 and April 2013.All data of the patients were collected from the medical records.patients were divided into two groups according to their survival:patients surviving less than 5 years and those who survived > 5 years.RESULTS:There were 34(14%) long term survivors(5 year survivors) among the 243 patients.Fiveyear survivors were younger at diagnosis than those surviving less than 5 years(mean age,50.47 ± 4.45 vs 54.59 ± 4.98,p = 0.001).Gender,clinical presentation,preoperative drainage,preoperative serum bilirubin,albumin and serum glutamic-pyruvic transaminase were similar between the two groups.The level of CA 19-9 was significantly higher in patients surviving < 5 years(395.71 ± 31.43 vs 254.06 ± 42.19,p = 0.0001).Univariate analysis demonstrated nine variables to be significantly associated with survival > 5 year,includingyoung age(p = 0.001),serum CA19-9(p = 0.0001),non-cirrhotic liver(p = 0.02),major hepatic resection(p = 0.001),caudate lobe resection(p = 0.006),well differentiated tumour(p = 0.03),lymph node status(0.008),R0 resection margin(p = 0.0001) and early postoperative liver cell failure(p = 0.02).CONCLUSION:Liver status,resection of caudate lobe,lymph node status,R0 resection and CA19-9 were demonstrated to be independent risk factors for long term survival.
基金Supported Partially by National Science Foundation of China (No.10571109,60573018)Science & Technology Research Project of Shanxi Higher-Education (No.20051277)
文摘The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of improved Support Vector Machine based on 1-norm(1-SVM) is provided from the optimization problem, yet it is a discrete programming. With the smoothing technique and optimality knowledge, the discrete programming is changed into a continuous programming. Experimental results show that the algorithm is easy to implement and this method can select and suppress the problem features more efficiently. Illustrative examples show that the 1-SVM deal with the linear or nonlinear classification well.
