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In order to solve the problems of difficult feature extraction and low recognition rate of radar signal at low signal-to-noise ratios, a dual channel convolutional neural network model based on Choi-Williams distribution (CWD) and multisynchrosqueezing transform (MSST) is proposed, which obtains two-dimensional time-frequency images by CWD and MSST time-frequency analyses on radar signals. Respectively, the time-frequency images are preprocessed and sequencely fed to a dual channel convolutional neural network for deep feature extraction. Finally, the features acquired by the two channels are fused, and the radar signal is classified and recognized through the convolutional neural network classifier. The simulation results show that when the signal-to-noise ratio is -10 dB, the overall recognition accuracy can reach above 96%, which is excellent at low signal-to-noise ratios.

Abstract Background Surgical patients are asked to fast for a sufficient duration to ensure that the amount of residual liquid in the stomach is within the safe range, thereby reducing the risk of gastric reflux perioperatively. The authors hypothesized that subjective hunger numerical rating scale (NRS) score could also help assess the process of gastric emptying and determine the amount of fluid remaining in the stomach. Methods The current study consisted of healthy volunteers recruited by advertisement and mutual introduction. Participants were asked to rate their subjective hunger feeling every 30 min after oral administration of 8 mL/kg carbohydrate nutrient solution that contained 10% maltodextrin and 2.5% sucrose. Consecutively, the gastric residual fluid was measured by magnetic resonance imagining (MRI). The Spearman’s correlation coefficient, the ROC curves and the stepwise regression were used to analyze the predictive value of NRS for the gastric emptying process. Results The cohort consisted of 29 healthy volunteers enrolled in this study. The area under ROC curves estimated by the NRS score for the gastric residual volume of 2 mL/kg, 1 mL/kg, and 0.5 mL/kg were AUC2.0 = 0.78, AUC1.0 = 0.76, and AUC0.5 = 0.72, respectively. The correlation coefficient between the NRS score and the residual liquid in the stomach was −0.57 (P

Due to the unique structural and optical anisotropy, colloidal quasi-two-dimensional nanoplatelets (NPLs) have been proposed as an important material platform for realizing quantum information technology. However, the optical and structural instability of emerging perovskite NPLs after rapid dilution is preventing such studies, along with an unknown intermediate evolution process. Herein, we investigate the photoluminescence evolution of CsPbBr3 NPLs during stepwise dilutions. Upon decreasing the concentration, a red shift of the emission peak can be observed in CsPbBr3 NPLs with different thicknesses and synthesis methods. The dilution ripening mechanism dominates this red-shifted photoluminescence, in which larger NPLs capture monomers when smaller NPLs are dissolved, and then the accumulated monomers increase the lateral size and thickness of large NPLs. Interestingly, the simple aging treatment can help improve the dilution stability of thicker NPLs of the hot-injection method. Moreover, it is confirmed that the dilution ripening effect can be suppressed by introducing PbBr2-saturated solution or exchanging pristine ligands with stronger binding ligands such as lecithin. [ABSTRACT FROM AUTHOR]

The concentration of microbes settled in rooms at different humidification levels (none-humidification, relative humidity is 40%, 55% and 70%) and in the humidifier storage water were investigated through experimental simulations and community analysis using a real office room as a prototype, to clarify the concentration and spatial distribution of microbes settled in winter heating rooms after ultrasonic humidification. The results show that the concentration of microbes settled indoors increases markedly after ultrasonic humidification and is closely related to the humidification level. The concentration is the largest under the medium humidification level. After 10-day humidification at medium target relative humidity (55%), the concentration of the settled bacteria (8.8x104 CFU/g) and fungi (5.9x104 CFU/g) roares to 13 times and 5 times of their original concentrations, respectively, far exceeding the standard's limitation (5x104 CFU/g) for microbes concentrations. The distribution of settled microbes shows significant spatial distribution characteristics, mainly accumulated on the floor and followed by the humidifier sprayer's leeward side, windward side, and flank side. The pathogenic bacterial genera, such as Brevundomonas spp., Legionella spp., expand fast in the water of the humidifier reservoir and are significantly correlated with the concentration of the bacteria settled indoors. [ABSTRACT FROM AUTHOR]