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Optical phased array (OPA), as a promising beam steering technology, however, usually suffers from a narrow field of view (FOV) that limits its performances in applications. A miniaturized compact strategy to enlarge the beam steering angle is quite desirable for the solid-state OPA technique. Here an on-chip metasurface-doublet is proposed to offer angle magnification integrated with a port-selected optical phased array. It is implemented by combing convex and concave metalenses with the quadratic phase distribution, which is precisely integrated on the OPA chip by layer-by-layer fabrication process. Here, the OPA is fabricated in Lithium Niobate on Insulator (LNOI) platform. Our experiments show that the metasurface-doublet is able to achieve 1.54 times FOV amplification in a horizontal direction and with >41% working efficiency. Our results provide a feasible approach to achieve enlarged FOV for wide-angle beam steering and also imply a powerful platform in developing integrated multilayer metasurface devices.

We present multi-parameter optimization of a shallow ridge InP-based traveling wave Mach-Zehnder modulator (MZM) for ultra-wide modulation bandwidth by velocity and impedance matching and microwave attenuation minimization. Relationship between MZM microwave loss and p-cladding layer doping profile is quantitatively analyzed and incorporated in device optimization. We propose a systematic analysis methodology allowing the full optimization of an InP shallow ridge MZM capable of 200 Gb/s PAM4 operation, compatible with high-volume low-cost manufacturing. Our design is expected to achieve 4.3 V half-wave voltage and 81 GHz 3-dB bandwidth with simplified fabrication process and improved long-term reliability.

Improving light extraction efficiency (LEE) of AlGaN-based deep-ultraviolet (DUV) light emitting diodes (LEDs) has been attempted by thinning the p-AlGaN/p-GaN layer and adopting Ni/Au/Al composite electrodes. It is found that the thin p-AlGaN/p-GaN layer can reduce the light absorption and the Ni/Au/Al electrodes achieve high reflectivity and Ohmic contact to ensure the enhancement of the light extraction and maintain fine electrical properties. By this approach, the maximum external quantum efficiency of the DUV-LEDs with optimized Ni/Au/Al reflective electrodes is increased by 40%, compared to that with conventional Ni/Au electrodes over the whole current range.

Abstract Background Postal screening has not previously been validated as a method for identifying fall and fracture risk in community-dwelling populations. We examined prognostic performance of a postal risk screener used in the UK Prevention of Falls Injury Trial (PreFIT; ISRCTN71002650), to predict any fall, recurrent falls, and fractures over 12 months. We tested whether adding variables would improve screener performance. Methods Nine thousand eight hundred and eight community-dwelling participants, aged 70 years and older, and 63 general practices in the UK National Health Service (NHS) were included in a large, pragmatic cluster randomised trial comparing screen and treat fall prevention interventions. The short postal screener was sent to all participants in the trial intervention arms as an A4 sheet to be completed and returned to the GP (n = 6,580). The postal screener items were embedded in the baseline pre-randomisation postal questionnaire for all arms of the trial (n = 9,808). We assessed discrimination and calibration using area under the curve (AUC). We identified additional predictors using data from the control arm and applied these coefficients to internal validation models in the intervention arm participants. We used logistic regression to identify additional predictor variables. Findings A total of 10,743 falls and 307 fractures were reported over 12 months. Over one third of participants 3,349/8,136 (41%) fell at least once over 12 month follow up. Response to the postal screener was high (5,779/6,580; 88%). Prediction models showed similar discriminatory ability in both control and intervention arms, with discrimination values for any fall AUC 0.67 (95% CI 0.65 to 0.68), and recurrent falls (AUC 0.71; 95% CI 0.69, 0.72) but poorer discrimination for fractures (AUC 0.60; 95% CI 0.56, 0.64). Additional predictor variables improved prediction of falls but had modest effect on fracture, where AUC rose to 0.71 (95% CI 0.67 to 0.74). Calibration slopes were very close to 1. Conclusion A short fall risk postal screener was acceptable for use in primary care but fall prediction was limited, although consistent with other tools. Fracture and fall prediction were only partially reliant on fall risk although were improved with the additional variables.

The formation of electron and hole traps in semiconductors via atomistic defects is the fundamental microscopic mechanism for tuning the electronic and photonic properties of these materials. Here we find in experiments that bismuth atoms doped into anatase TiO2 as substituents can appear as paired diatomic defects. Through first-principles density functional theory calculations, we reveal that the observed bismuth pair is separated by a medium distance of 6.37 Å through a delicate balance of Pauli repulsion and effective attractive interaction. We further clarify that the effective attractive interaction is related to the exchange coupling between the two bismuth defect states, which also leads to the formation of a spin singlet electronic state of the two unpaired electrons. Our study brings up a new type of defect state in TiO2, and motivates further experimental and theoretical studies of multi-electronic states in materials. [ABSTRACT FROM AUTHOR]

Metabolic reprogramming is considered to be one of the top characteristics of tumor cells. Ample experimental studies have shown that microRNAs, which are a group of multifunctional non-coding RNAs, play an important role in the development of hepatocellular carcinoma (HCC) through lipid metabolic reprogramming. The current review briefly introduces the recent progress of specific microRNAs targeting at lipid metabolic reprogramming in HCC, which may provide a potential strategy for clinical targeting tumor therapy.

While there is a strong assumption of a direct link between family climate and school bullying victimization, studies on such a direct link have shown inconsistent results. Furthermore, family climate and children's social relationships with teachers and peers at school have been considered potential protective factors against school bullying victimization among adolescents. However, not much is known about how these factors function as protectors against school bullying victimization among children early in middle childhood. Studies examining how these protective factors work together to reduce school bullying victimization are also lacking. This paper attempts to fill the gap by studying how children's social relationships with peers and teachers at school mediate the association of family climate with school bullying victimization among children in the early period of their middle childhood in Taiwan. It also examines how sex influences the mediating effects and interrelationships among family climate, children's school social relationships at school, and school bullying victimization. Data were obtained from a nationally representative sample of 1230 third graders (about 8 years old) in Taiwan. The results showed that family climate had a nonsignificant direct link with school bullying victimization, but a significant indirect link with school bullying victimization mediated through relationships with peers and teachers. These findings are relevant for both sexes. Findings provide empirical support that family climate has an indirect link with school bullying victimization through relationships with teachers and peers. The study indicated that to reduce school bullying victimization among those who are early in middle childhood, potential intervention programs may consider promoting students' relationships with teachers and peers.

Although previous research has indicated an association between school engagement and adolescent victimization, its causal direction has not been determined, particularly in Chinese and East Asian cultural contexts. This study used a longitudinal panel data to explore the likely causal direction between school engagement and adolescent victimization in the context of school and cyberspace. Three hundred fifty-six students and their homeroom teachers in lower secondary school (Grades 7-9) in Hong Kong participated in a 2-wave panel study with a 9-month time interval. Students provided self-report information on their experiences with school violence and cyberbullying, and their homeroom teachers assessed their students' engagement in school. The results of latent variables and autoregressive cross-lagged panel analysis suggested that school engagement at wave 1 was a significant predictor of school victimization at wave 2, but school victimization at wave 1 did not predict school engagement at wave 2. Similarly, school engagement at wave 1 was a significant predictor of cyberbullying victimization at wave 2, but school victimization at wave 1 did not predict school engagement at wave 2. These findings were also relevant for both sexes. The findings demonstrated that school engagement could be a protective factor against adolescent exposure to violence in school and cyberspace in Hong Kong. The findings informed school practitioners in Hong Kong that increasing student engagement in school could be a key strategy to reduce students' risk of being bullied in school and cyberspace.