Radar Micro-Doppler Signature Generation Based on Time-Domain Digital Coding Metasurface.

Micro-Doppler effect is a vital feature of a target that reflects its oscillatory motions apart from bulk motion and provides an important evidence for target recognition with radars. However, establishing the micro-Doppler database poses a great challenge, since plenty of experiments are required to get the micro-Doppler signatures of different targets for the purpose of analyses and interpretations with radars, which are dramatically limited by high cost and time-consuming. Aiming to overcome these limits, a low-cost and powerful simulation platform of the micro-Doppler effects is proposed based on time-domain digital coding metasurface (TDCM). Owing to the outstanding capabilities of TDCM in generating and manipulating nonlinear harmonics during wave-matter interactions, it enables to supply rich and high-precision electromagnetic signals with multiple micro-Doppler frequencies to describe the micro-motions of different objects, which are especially favored for the training of artificial intelligence algorithms in automatic target recognition and benefit a host of applications like imaging and biosensing.

Manipulations of multi-frequency waves and signals via multi-partition asynchronous space-time-coding digital metasurface.

Manipulations of multiple carrier frequencies are especially important in a variety of fields like radar detection and wireless communications. In conventional radio-frequency architecture, the multi-frequency control is implemented by microwave circuits, which are hard to integrate with antenna apertures, thus bringing the problems of expensive system and high power consumption. Previous studies demonstrate the possibility to jointly control the multiple harmonics using space-time-coding digital metasurface, but suffer from the drawback of inherent harmonic entanglement. To overcome the difficulties, we propose a multi-partition asynchronous space-time-coding digital metasurface (ASTCM) to generate and manipulate multiple frequencies with more flexibility. We further establish an ASTCM-based transmitter to realize wireless communications with frequency-division multiplexing, where the metasurface is responsible for carrier-wave generations and signal modulations. The direct multi-frequency controls with ASTCM provides a new avenue to simplify the traditional wireless systems with reduced costs and low power consumption.

Toward Sub-Terahertz: Space-Time Coding Metasurface Transmitter for Wideband Wireless Communications.

A space-time coding metasurface (STCM) operating in the sub-terahertz band to construct new-architecture wireless communication systems is proposed. Specifically, a programmable STCM is designed with varactor-diode-tuned metasurface elements, enabling precise regulation of harmonic amplitudes and phases by adjusting the time delay and duty cycle of square-wave modulation signal loaded on the varactor diodes. Independent electromagnetic (EM) regulations in the space and time domains are achieved by STCM to realize flexible beam manipulations and information modulations. Based on these features, a sub-terahertz wireless communication link is constructed by employing STCM as a transmitter. Experimental results demonstrate that the STCM supports multiple modulation schemes including frequency-shift keying, phase-shift keying, and quadrature amplitude modulations in a wide frequency band. It is also shown that the STCM is capable of realizing wide-angle beam scanning in the range of ±45o , which offers an opportunity for user tracking during the communication. Thus, the STCM transmitter with high device density and low power consumption can provide low-complexity, low-cost, low-power, and low-heat solutions for building the next-generation wireless communication systems in the sub-terahertz frequency and even terahertz band.

Frequency-modulated continuous waves controlled by space-time-coding metasurface with nonlinearly periodic phases.

The rapid development of space-time-coding metasurfaces (STCMs) offers a new avenue to manipulate spatial electromagnetic beams, waveforms, and frequency spectra simultaneously with high efficiency. To date, most studies are primarily focused on harmonic generations and independent controls of finite-order harmonics and their spatial waves, but the manipulations of continuously temporal waveforms that include much rich frequency spectral components are still limited in both theory and experiment based on STCM. Here, we propose a theoretical framework and method to generate frequency-modulated continuous waves (FMCWs) and control their spatial propagation behaviors simultaneously via a novel STCM with nonlinearly periodic phases. Since the carrier frequency of FMCW changes with time rapidly, we can produce customized time-varying reflection phases at will by the required FMCW under the illumination of a monochromatic wave. More importantly, the propagation directions of the time-varying beams can be controlled by encoding the metasurface with different initial phase gradients. A programmable STCM prototype with a full-phase range is designed and fabricated to realize reprogrammable FMCW functions, and experimental results show good agreement with the theoretical analyses.

Risk factors for depth of infiltration in the differentiated depressed early gastric carcinoma: a preliminary analysis.

BACKGROUND: To analyze the clinicopathologic factors associated with mucosal and submucosal infiltration in differentiated depressed early gastric cancer, and screening factors that can predict depth of infiltration before endoscopic treatment. METHODS: The study included 35 cases of mucosal carcinomas and 66 cases of submucosal carcinomas according to the pathological diagnosis. The relevant clinicopathologic factors were investigated by univariate and multivariate analysis. RESULTS: The average depth of the depressed lesions for the submucosal group was significantly more than that for the mucosal group. The proportion of the lesions with rough bottom surface and abnormal surrounding folds was significantly higher in the submucosal group compared to that in the mucosal group. Logistic regression analysis indicated that the above-mentioned three factors were independent risk factors that could be used to predict mucosal and submucosal infiltration. Area under the curve (AUC) of receiver operating characteristic (ROC) of the ordinal above-mentioned three factors for predicting submucosal infiltration was 0.716, 0.663, 0.704, respectively. Stratified analysis showed that the 100% cases with lesion depth ≥ 2.5 mm and rough bottom surface developed submucosal infiltration regardless of the morphological changes of the folds. CONCLUSION: The study identified independent risk factors for predicting mucosal and submucosal infiltration in depressed differentiated early gastric cancer, which may evaluate the degree of penetration before endoscopic treatment. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_206.

[Construction of RegIα over-expression vector and its effect on proliferation and apoptosis of gastric cancer cells].

OBJECTIVE: To construct RegIα over-expression vector and to evaluate the effect of RegIα on the proliferation and apoptosis of gastric cancer MKN28 cells in vitro. METHODS: Full sequence of RegIα cDNA was amplified from normal gastric tissue samples by RT-PCR and cloned into pIRES2-EGFP vector. RT-PCR and Western blot were performed to detect expression levels of RegIα in MKN28 cells. The effects of over-expression RegIα on cell proliferation was measured by MTT assay and apoptosis was detected by flow cytometry. RESULT: RegIα cDNA over-expression vector of pIRES2-RegIα-EGFP was successfully constructed. The expressions of RegIα in MKN28 cells, including mRNA and protein levels, were significantly increased after stable transfection, which resulted in cell proliferation and anti-apoptotic effect induced by H(2)O(2). CONCLUSION: The over-expression of RegIα can promote cell proliferation and reduce cell apoptosis when induced by H(2)O(2) in gastric cancer cells.

Muscovite reverses gastric gland atrophy and intestinal metaplasia by promoting cell proliferation in rats with atrophic gastritis.

OBJECTIVE: To detect whether muscovite exerts its protective role in the progression of atrophic gastritis (AG) and evaluate the possible mechanism. METHODS: AG rats were established and then randomly divided into groups administrated with different doses of muscovite for 8 weeks. Histological changes in gastric antrum and the number of parietal cells, chief cells, and G/D cells were observed. Serum gastrin and prostaglandin E2 (PGE2) were evaluated by enzyme-linked immunosorbent assay (ELISA). The expression of proliferating cell nuclear antigen (PCNA), epidermal growth factor receptor (EGFR), C-erbB-2, p21, p53, p16 and bcl-2 in gastric tissue were detected by immunohistochemistry. The concentrations of TNF-alpha and IL-1beta secreted by THP-1 cells were detected when incubated with different doses of muscovite. RESULTS: The grade of inflammation in muscovite groups was lower (p < 0.05), while the thickness and number of gastric glands were significantly elevated in muscovite groups (p < 0.01). The expression height of PCNA in the muscovite group was higher than in the AG group (p < 0.01). Immunohistochemistry results showed a positive expression rate of EGFR; p16 in muscovite-treated AG rats was increased (p < 0.05), while C-erbB-2 and p21 were decreased (p < 0.05). Serum gastrin and PGE2 were significantly elevated in the high-dose muscovite-treated rats (p < 0.05). In vitro studies showed that muscovite had a dose-dependent adsorption of TNF-alpha and IL-1beta. CONCLUSION: Muscovite could reverse gastric gland atrophy and intestinal metaplasia by promoting cell proliferation and revitalization in gastric mucosa in AG rats.