Gastric cancer is a highly heterogeneous disease and the second leading cause of cancer-associated mortality. However, the genomic basis of gastric cancer is not completely understood and the underlying genetic heterogeneity has not been well studied. In the present study, 1,021 genes were sequenced and the somatic mutations of 45 formalin-fixed, paraffin-embedded gastric adenocarcinoma samples were assessed using next-generation sequencing technologies. In the present study, a median sequencing coverage depth of 708-fold was achieved. Somatic genomic alterations were detected in 37/45 patients (82.4%) and the most frequent genetic alterations identified were tumor protein P53 (TP53) gene mutations. Mutations in MLL4, ERBB3, FBXW7, MLL3, MTOR, NOTCH1, PIK3CA, KRAS, ERBB4 and EGFR were also detected. Patients with TP53 mutations had a higher number of somatic mutations, and the total number of somatic mutations was weakly correlated with patient age. These results provided data on the intratumoral heterogeneity of gastric cancer and may be used in order to develop personalized cancer therapy.
The conflict between heavy training overhead and large beamforming gain is a bottleneck to deploy millimeter-wave (mmWave) communications for the next-generation wireless networks. In response, this paper proposes a subarray-cooperation-based multi-resolution codebook design and the corresponding beam alignment scheme, which enables the mmWave backhaul links to quickly align the desired beam pairs under single-dominant-path channels. The proposed codebook is of a hybrid digital/analog structure, in which the digital component selects subarrays and handles the coupling impacts among the selected subarrays, and the analog component shapes essential sub-beams using phase-shifter groups. In particular, the analog beamformers are configured as equal-size discrete Fourier transform vectors, which are easy to implement. The resulting beam alignment method adaptively selects initial layers according to different transmission signal-to-noise ratios, guaranteeing sufficient success ratios on angle detection. The numerical results evaluate the effectiveness of the proposed scheme. INDEX TERMS Backhaul link, beam alignment/training, millimeter-wave (mmWave), multi-resolution codebook.
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