Time domain turbo equalization based on vector approximate message passing for multiple-input multiple-output underwater acoustic communications.

This paper proposes a high-performance receiver for underwater acoustic communications based on time reversal processing for multiple-input multiple-output (MIMO) systems. The receiver employs the vector approximate message passing (VAMP) algorithm as a soft equalizer in turbo equalization. By performing self-iteration between the inner soft slicer and the inner soft equalizer, the VAMP algorithm achieves near-optimal performance. Furthermore, an iterative channel-estimation-based soft successive interference cancellation method is incorporated to suppress co-channel interference in the MIMO system. Additionally, the introduction of passive time reversal technology can combine multiple channels into a single channel, which greatly reduces the computational complexity of the MIMO system, especially for large MIMO systems. The effectiveness of the proposed receiver is verified using experimental data collected in Songhua Lake, China in 2019. The results demonstrate that the proposed receiver significantly reduces the complexity of the traditional parallel-VAMP receiver without sacrificing performance and outperforms other receivers of the same type. Moreover, our experimental results also verify that the VAMP-turbo outperforms the generalized approximate message passing (GAMP)-turbo in terms of bit error rate and convergence performance.

Robust symbol detection for single-carrier underwater acoustic communication in impulsive noise environment.

This paper addresses robust underwater acoustic communication in the presence of impulsive noise. We propose a single-carrier iterative symbol detection method, which combines variational Bayesian inference (VBI) and vector approximate message passing (VAMP) for impulsive noise cancellation. Unlike existing methods, we model the measurements as a combination of two components: clean data without impulsive noise and impulse-noise-induced outliers. A set of binary indicator variables is used to identify outliers automatically. Under the proposed mixed model, we derive a VBI-based symbol detection method that can alternatively detect communication symbols and impulsive noise, and compensate for the impulsive noise when detecting communication symbols. To further improve detection performance, we integrate the VAMP into the VBI framework for communication symbols detection. Additionally, to reduce the overall complexity of the communication system, we propose a channel estimation method based on damped generalized approximate message passing. Simulation and experimental results show that the proposed detection method outperforms existing methods in terms of robustness and bit error rate.

Iterative channel estimation-based soft successive interference cancellation for multiuser underwater acoustic communications.

This paper presents a single-carrier multiuser receiver in underwater acoustic communications with strong multiple access interference (MAI) combining passive time-reversal (PTR) and direct-adaptation-based turbo equalization. The receiver works in an iterative block by block manner. In the first iteration, when the symbols of all users are detected by successive interference cancellation (SIC) in the block, the channel impulse response (CIR) of each user is then updated by post-SIC signal to achieve more accurate MAI reconstruction and PTR combination for the next block. In the following iterations, the a priori mean of symbol in the current block is available and used to further improve the accuracy of reconstructed MAI and the updated CIR. The proposed receiver is demonstrated using experimental data collected at Songhua Lake, China, in 2019. The results show that single-carrier nine-user communication data with quadrature phase-shift keying can be successfully recovered, with an average data rate of 1.67 kbps for each user.

Infant pleuropulmonary blastoma: report of a rare case and review of literature.

In infants, pleuropulmonary blastoma is a rare but aggressive tumor. The typical histopathological presentation includes the aggregation of malignant primitive small cells, usually observed in sheets. So as to provide proper and timely treatment, the differential diagnosis includes pulmonary blastoma, sarcomatoid mesothelioma, fetal rhabdomyoma, synovial sarcoma, and primitive neuroectodermal tumor. Herein, we will present one male pediatric patient with pleuropulmonary blastoma. The patient was a 4-month-old male infant, who had a prolonged cough and dyspnea for 4 months that was complicated by cyanosis for 3 days. A physical examination revealed a solid mass in the right lung that was sized 9.0 × 6.0 × 4.0 cm and had a grayish-white cross section. The boundary between the mass and lung tissue was clear; the mass already occupied a great portion of the lung. A microscopic examination suggested that the tumor was composed of round or orbicular-ovate primitive fetal cells. The cells were medium sized, having little cytoplasm, but had a clearly visualized nucleolus and active karyokinesis. The tumor mass was biphasic, namely, fasciculated sarcoma (composed of spindle-shaped cells and short spindle-shaped cells) and malignant fibrous histiocytoma containing well-differentiated cartilage islands or cartilaginous nodes. Immunohistochemistry was performed for further detection: vimentin (+), S-100 protein (+), CK (AE1/AE3), EMA and TTF-1 in residual epithelial components (+), NSE (focal +), SMA (mesenchymal cells, focal +), CD99 (weak +), Bcl-2 (weak +), desmin (-), myoglobin (-), calretinin (-), calponin (-), FLI (-), MyoD-1 (-), and CD34 (-). Pleuropulmonary blastoma is extremely rare but highly aggressive neoplasm in children. Its typical histopathological presentation is the aggregation of primitive malignant small cells. Combining imaging and histopathological examinations and clinical data should help in determining the diagnosis of pleural pulmonary blastoma.

Detection of Her-2/neu expression in gastric cancer: Quantitative PCR versus immunohistochemistry.

The aim of this study was to compare quantitative polymerase chain reaction (qPCR) with immunohistochemistry (IHC) for the detection of Her-2 in gastric cancer, and to investigate the correlation between the expression levels of human epidermal growth factor receptor 2 (Her-2) and clinical features. Clinical data from 426 cases of gastric cancer were collected. Her-2 expression levels in cancerous tissue were detected using IHC, and the Her-2/neu gene expression levels were determined by qPCR. The correlation between the expression level of Her-2 and clinical features was investigated. The positive expression rate of Her-2 in cancerous tissue detected using qPCR and IHC was 11.17% (46/412) and 13.38% (57/426), respectively. The positive expression of the Her-2 protein/gene was significantly correlated with the depth of invasion and lymphatic metastasis, as well as the TNM stage (P<0.05). No significant correlation was identified between positive expression of the Her-2 protein/gene and tumor location, age, gender, differentiation degree and Lauren classification (P>0.05). The diagnostic consistency was good between the two methods (κ=0.828). The results indicate that the expression of Her-2/neu is closely associated with the development of gastric cancer. qPCR is a convenient, objective and efficient method, which may be used as an alternative to IHC or fluorescence in situ hybridization for the detection of Her-2/neu gene.