Photonic parallel channel estimation of MIMO-OFDM wireless communication systems.

Channel estimation is a key technology in MIMO-OFDM wireless communication systems. Increasingly extensive application scenarios and exponentially growing data volumes of MIMO-OFDM systems have imposed greater challenges on the speed, latency, and parallelism of channel estimation based on electronic processors. Here, we propose a photonic parallel channel estimation (PPCE) architecture which features radio-frequency direct processing. Proof-of-concept experiment is carried out to demonstrate the general feasibility of the proposed architecture at different frequency bands (100 MHz, 4 GHz, and 10 GHz). The mean square errors (MSEs) between the experimental channel estimation results and the theoretically simulated ones lie on the order of 10-3. The bit error rates (BERs) are below the pre-forward error correction (pre-FEC) threshold. Besides, we analyze the performance of PPCE under different signal-to-noise ratios (SNRs), baseband symbol forms, and weight tuning precisions. The proposed PPCE architecture has the potential to achieve high-speed, highly parallel channel estimation in large-scale MIMO-OFDM systems after the photonic-electronic chip integration.

High-resolution ISAR imaging based on photonic receiving for high-accuracy automatic target recognition.

A scheme of high-resolution inverse synthetic aperture radar (ISAR) imaging based on photonic receiving is demonstrated. In the scheme, the linear frequency modulated (LFM) pulse echoes with 8 GHz bandwidth at the center frequency of 36 GHz are directly sampled with the photonic analog-to-digital converter (PADC). The ISAR images of complex targets can be constructed without detection range swath limitation due to the fidelity of the sampled results. The images of two pyramids demonstrate that the two-dimension (2D) resolution is 3.3 cm × 1.9 cm. Furthermore, the automatic target recognition (ATR) is employed based on the high-resolution experimental dataset under the assistance of deep learning. Despite of the small training dataset containing only 50 samples for each model, the ATR accuracy of three complex targets is still validated to be 95% on a test dataset with the equal number of samples.

Equivalence of photonic sampling to signal holding in channel-interleaved photonic ADCs by controlling photo-detection response.

Substantial interests have been attracted in the use of photonic sampling and electronic digitizing for photonic analog-to-digital converter (PADC). However, the nature of that photo-detection with signal holding effects has not been well established. This paper analyzes the equivalence of photonic sampling to signal holding by controlling photo-detection response. In the frequency domain, the high-frequency components generated by the sampling pulse train are folded back into the Nyquist band resulting the signal holding response when the output is digitized. We proposed an approximate response of the photodetector (PD) to verify the theoretical analysis. It is found that the photonic sampling serves as the conventional switch-based sample-and-hold (S&H) circuit in channel-interleaved photonic analog-to-digital converter. In the experiment, the signal holding directly inhibits the timing mismatch without sophisticated calibrations.

Photonic ADC-based scheme for joint wireless communication and radar by adopting a broadband OFDM shared signal.

We propose and demonstrate a novel, to the best of our knowledge, joint wireless communication and radar system based on a photonic analog-to-digital converter (PADC), which can receive broadband radio-frequency (RF) signals. Owing to this property, a broadband orthogonal frequency division multiplexing (OFDM) shared signal, which owns obvious advantages in communication applications, can be adopted to realize efficient data communication and high-performance target detection simultaneously. In the experiment, a communication rate of 6 Gbit/s is achieved. Inverse synthetic aperture radar (ISAR) imaging is demonstrated with a two-dimensional (2D) resolution of 3.97 cm × 2.94 cm. Finally, it is verified that high-accuracy radial resolution and high-speed communication can be maintained while increasing the pulse repetition period to detect remote target at around 374.6 m.

PTP1B markedly promotes breast cancer progression and is regulated by miR-193a-3p.

The protein tyrosine phosphatase PTP1B, which is encoded by PTPN1, is a ubiquitously expressed nonreceptor protein tyrosine phosphatase. PTP1B has long been known to negatively regulate insulin and leptin receptor signalling. Recently, it was reported to be aberrantly expressed in cancer cells and to function as an important oncogene. In this study, we found that PTP1B protein levels are dramatically increased in breast cancer (BC) tissues and that PTP1B promotes the proliferation, and suppresses the apoptosis, of both HER2-positive and triple-negative BC cell lines. Bioinformatics analysis identified that the miRNA, miR-193a-3p, might potentially target PTP1B. We demonstrate that miR-193a-3p regulates PTP1B in BC cells and that it regulates the proliferation and apoptosis of BC cells by targeting PTP1B, both in vitro and in vivo. In conclusion, this study confirms that PTP1B acts as an oncogene in BC and demonstrates that miR-193a-3p can serve as a tumour suppressor gene in BC by targeting PTP1B.

Mechanisms of wheat (Triticum aestivum) grain storage proteins in response to nitrogen application and its impacts on processing quality.

Basis for the effects of nitrogen (N) on wheat grain storage proteins (GSPs) and on the establishment of processing quality are far from clear. The response of GSPs and processing quality parameters to four N levels of four common wheat cultivars were investigated at two sites over two growing seasons. Except gluten index (GI), processing quality parameters as well as GSPs quantities were remarkably improved by increasing N level. N level explained 4.2~59.2% and 10.4~80.0% variability in GSPs fractions and processing quality parameters, respectively. The amount of N remobilized from vegetative organs except spike was significantly increased when enhancing N application. GSPs fractions and processing quality parameters except GI were only highly and positively correlated with the amount of N remobilized from stem with sheath. N reassimilation in grain was remarkably strengthened by the elevated activity and expression level of glutamine synthetase. Transcriptome analysis showed the molecular mechanism of seeds in response to N levels during 10~35 days post anthesis. Collectively, we provided comprehensive understanding of N-responding mechanisms with respect to wheat processing quality from N source to GSPs biosynthesis at the agronomic, physiological and molecular levels, and screened candidate genes for quality breeding.