The coronavirus disease 2019 (COVID-19) pandemic has rapidly spread all over the world. Lung ultrasound (LUS) has emerged as a useful tool for diagnosing many respiratory diseases. The prognostic role of LUS in COVID-19 patients has not yet been established. Several databases were searched on 09 April 2021. The difference in LUS score between the death and survival groups, and the relationship between LUS score and COVID-19 severity were both assessed. The LUS score was significantly higher in the death group compared with the survival group (weighted mean difference (WMD) = 8.21, 95% CI: 4.74-11.67, P < 0.001), which was confirmed by trial sequential analysis. Those with mild/moderate, severe and critical COVID-19 had a progressively higher LUS score (critical vs. severe: WMD = 8.78, 95% CI: 4.17-13.38; P < 0.001; critical vs. mild/moderate/severe: WMD = 10.00, 95% CI: 6.83-13.17, P < 0.001; severe vs. moderate: WMD = 5.96, 95% CI: 3.48-8.44, P < 0.001; severe vs. mild/moderate: WMD = 7.31, 95% CI: 4.45-10.17, P < 0.001). The LUS score was associated with mortality and severity of COVID-19. The LUS score might be a risk stratification tool for COVID-19 patients.

Background: Duchenne muscular dystrophy (DMD) is the most common form of inherited muscle disease in children. The incidence of cardiomyopathy induced by DMD increases with age. Left ventricular ejection fraction usually fails to reflect the subclinical left ventricular dysfunction. Several studies have assessed this dysfunction using myocardial strain measured by speckle-tracking echocardiography (STE). However, the results were inconsistent and incomplete. Methods: Several databases were searched from their inception to February 5, 2020. The summarized weighted mean difference (WMD) with 95% confidence intervals (CIs) were estimated for myocardial strain between DMD and healthy controls and a meta-analysis was conducted. Trial sequential analysis estimated whether the resulting evidence was sufficient. Results: Eight studies with a total of 269 DMD children and 299 healthy participants were included. STE revealed that global longitudinal strain (GLS), global circumferential strain, average longitudinal strain (measured by two-dimensional STE at the apical four-chamber view), and average circumferential strain (measured by two-dimensional STE at the papillary muscle short-axis level) decreased (WMD = 4.17, 95% CI: 3.03–5.32; WMD = 3.98, 95% CI: 0.29–7.68; WMD = 4.18, 95% CI: 2.75–5.62; and WMD = 4.90, 95% CI: 2.38–7.43, respectively; all P < 0.05) compared with the controls and global radial strain was unchanged in the DMD group (WMD = − 4.33, 95% CI: − 9.53–0.87, P = 0.103). Trial sequential analysis indicated that available GLS samples were sufficient and confirmed that adequate evidence was accumulated. The credibility of other myocardial strains was questioned due to insufficiently involved studies. Conclusion: GLS can be useful for early detection of left ventricle myocardial dysfunction in children with DMD.

We experimentally demonstrated a long-range, large-capacity-featured, airship-based, free-space optical transmission system by using key technologies, such as GPS/INS real-time precision laser pointing, coarse and fine compound high-bandwidth laser tracking, avalanche photodiode detector adaptive control turbulence channel compensation, and the aurora laser fifth-generation (5G) interface protocol, to solve the problems of laser tracking and targeting based on an airship motion platform, high-speed signal transmission under atmospheric channel perturbation, and interface protocol between a wireless laser link and 5G base station signal, respectively. To the best of our knowledge, the first FSO transmission of 5G base station signals between airship platforms with a rate of 2.5 Gbps and a distance of 12 km was realized, and channel turbulence jitter was also recorded for laser links of different altitudes, from 200 to 1000 m, which provides technical and data support for the application of wireless laser links in 5G floating base stations.

This study proposes a method to reduce link loss in near-ground space laser communication with fiber-nutation-based mutual coupling. We designed a transmit-receive coaxial laser terminal with a 50 mm aperture and implemented beam acquisition tracking and nutation coupling using a single-detector and single-actuator. Following an indoor experiment and a 1 km field test, the single-ended nutation coupling and the two-way nutation mutual coupling theories were compared and analyzed. In conclusion, the proposed method could significantly increase the reception efficiency by ∼8 dB. The bit error rate of 10 Gbps pseudo-random code transmission was 2.478E-9. We also demonstrated video transmission.

Optical Phase Arrays (OPAs) are expected to be an ideal solution to achieve beam shaping, laser radar (LIDAR), free-space optical communications, and spatially resolved optical sensors, etc. We demonstrated a low-power consumption 32-channel OPA with non-uniformly spaced waveguides based on InP substrate. The phase shifters are based on a p-i-n structure which are operated with reverse bias and have a low power consumption. Besides, in order to improve the performance especially to obtain larger steering angle and narrower beam divergence without increasing the number of channels, we have optimized the spacing between the output waveguides. The fabricated OPA achieved a steering angle of 35° with the side lobe suppression ratio more than 8.2 dB across the angle range from -20° to 20° in the far field, which is the largest phase tuning steering angle reported by InP-based OPAs as far as we know. The divergence angle is about 0.46° in the phase steering dimension and the power consumption of the OPA at each steering angle is lower than 7.5 mW.