Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from ...Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from the deviation from the right operation bias voltage and unbalanced amplitude, and the phase of the radio frequency （RF） drive signals on the performance of the multi-tone source are discussed in detail. Based on the theoretical analysis, high-quality 50-tone out- put is successfully realized. Experiments under some implementation imperfections are also carried out. The imperfect and low-quality output results are in good agreement with theoretical analysis.展开更多
Purpose: Group B Streptococcus (GBS) infection is a major cause of neonatal sepsis. The objective of this study was to estimate the prevalence and risk factors for GBS carriership among parturient women in Jerusalem. ...Purpose: Group B Streptococcus (GBS) infection is a major cause of neonatal sepsis. The objective of this study was to estimate the prevalence and risk factors for GBS carriership among parturient women in Jerusalem. Methods: A cross-sectional study of 436 parturient Jewish women at Hadassah-Hebrew University Medical Center, Mount Scopus. The study included patient interview and vagino-rectal swab for culture. Main outcome measures were the prevalence of GBS carriership among study population. Results: Of the 436 participants, 77 had a positive culture for GBS, giving a carrier rate of 17.7%. No differences were found between carriers and non-carriers in age, BMI or parity. Orthodox Jewish women had a significantly higher carrier rate compared with secular Jewish women (20.6% vs. 12.8% respectively), yielding an age, education and BMI adjusted odds ratio (OR) of 1.9 (95% confidence interval (CI): 1.06 - 3.40). Similarly, ritual immersion was associated with increased risk of carrier state with an adjusted OR of 2.01 (95% CI: 1.03 - 3.92, P = 0.039). Conclusions: Our study suggests an association between ritual immersion in the Mikveh and GBS carriership.展开更多
This paper applies the repetition index scheme(RIS)to the channel identification of cyclic prefixed(CP)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)systems with virtual carriers(...This paper applies the repetition index scheme(RIS)to the channel identification of cyclic prefixed(CP)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)systems with virtual carriers(VCs)in the environment of the number of receive antennas being no less than that of transmit antennas.The VCs will cause a rank deficiency problem in computing the subspace information.With the subcarrier mapping matrix,the received signal is simplified to remove the rank deficiency.We use the RIS scheme to generate many times of equivalent symbols so the channel identification can converge with few received OFDM blocks.The RIS scheme will convert the white noise into non-white noise.With the Cholesky factorization,a noise whitening technique is developed to turn the non-white noise back to white noise.We further analyze the necessary conditions of identifiability of channel estimation.Simulations are performed to show the superiority of the proposed method.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.60977049)the Chinese Universities Scientific Fund (Grant No.BUPT 2009RC0413)
文摘Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from the deviation from the right operation bias voltage and unbalanced amplitude, and the phase of the radio frequency （RF） drive signals on the performance of the multi-tone source are discussed in detail. Based on the theoretical analysis, high-quality 50-tone out- put is successfully realized. Experiments under some implementation imperfections are also carried out. The imperfect and low-quality output results are in good agreement with theoretical analysis.
文摘Purpose: Group B Streptococcus (GBS) infection is a major cause of neonatal sepsis. The objective of this study was to estimate the prevalence and risk factors for GBS carriership among parturient women in Jerusalem. Methods: A cross-sectional study of 436 parturient Jewish women at Hadassah-Hebrew University Medical Center, Mount Scopus. The study included patient interview and vagino-rectal swab for culture. Main outcome measures were the prevalence of GBS carriership among study population. Results: Of the 436 participants, 77 had a positive culture for GBS, giving a carrier rate of 17.7%. No differences were found between carriers and non-carriers in age, BMI or parity. Orthodox Jewish women had a significantly higher carrier rate compared with secular Jewish women (20.6% vs. 12.8% respectively), yielding an age, education and BMI adjusted odds ratio (OR) of 1.9 (95% confidence interval (CI): 1.06 - 3.40). Similarly, ritual immersion was associated with increased risk of carrier state with an adjusted OR of 2.01 (95% CI: 1.03 - 3.92, P = 0.039). Conclusions: Our study suggests an association between ritual immersion in the Mikveh and GBS carriership.
基金Fujian Province Education Department(No.JAT170470)in part by the National Nature Science Foundation of China(No.61501041)+1 种基金in part by the Open Foundation of State Key Laboratory(No.ISN19-19)in part by the Ministry of Science and Technology,Taiwan,China(No.MOST 104-2221-E-030-004-MY2,MOST 108-2221-E-030-002).
文摘This paper applies the repetition index scheme(RIS)to the channel identification of cyclic prefixed(CP)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)systems with virtual carriers(VCs)in the environment of the number of receive antennas being no less than that of transmit antennas.The VCs will cause a rank deficiency problem in computing the subspace information.With the subcarrier mapping matrix,the received signal is simplified to remove the rank deficiency.We use the RIS scheme to generate many times of equivalent symbols so the channel identification can converge with few received OFDM blocks.The RIS scheme will convert the white noise into non-white noise.With the Cholesky factorization,a noise whitening technique is developed to turn the non-white noise back to white noise.We further analyze the necessary conditions of identifiability of channel estimation.Simulations are performed to show the superiority of the proposed method.
文摘在传统两电平整流器(the conventional two-level rectifier,CTR)电路中,开关管需要承受整个直流侧的电压,输入侧滤波器的体积较大,电路的传输效率较低,为此提出了基于双开关单元的多电平电路。首先,在CTR的基础上增加了1个二极管和1个电容,得到(similar to a three-level rectifier,STR)电路,并根据STR电路推出了几种多电平结构。然后,以新型三电平整流器(new three-level rectifier,NTR)拓扑结构为例,进行了工作原理分析。最后,提出合适的调制技术和电压平衡策略,并对器件的电压、电流应力进行理论计算。与CTR电路相比,NTR能降低开关管电压应力,减小开关管的开关频率,提高输入侧电流质量,适用于中、小功率应用场合。
