Background Previous studies of very low birth weight (VLBW) hospital volume effects on inhospital mortality have used standard risk-adjusted models that only account for observable confounders but not for self-selection bias due to unobservable confounders. Objective To assess the effects of hospital volume of VLBW infants on in-hospital mortality while explicitly accounting for unobservable confounders and self-selection bias using an instrumental-variables model. Methods The sample includes 4,553 VLBW infants born in 63 hospitals in 2000–2004 in New Jersey. We employ instrumental-variables analysis using as instruments the differences between the patient’s distances to the nearest low (<50 VLBW infants annually), moderate (51–100 infants annually) and high (>100 VLBW infants annually) volume hospitals. We evaluate several volume measures and adjust for observable infant and hospital characteristics. Results We find beneficial volume effects on survival that are significantly underestimated in classical risk-adjusted models, under which low and moderate volumes compared to high volumes increase mortality odds by 1.8 and 1.88 times, respectively (risk ratios of 1.4 and 1.5, respectively). However, using an instrumental variables approach, we find that low and moderate volumes increase mortality odds by 5.42 and 3.51 times, respectively (risk ratios of 2.76 and 2.21, respectively). These findings suggest unobservable confounders that increase the selection of infants at a greater mortality risk into higher volume hospitals. Conclusions Accounting for unobserved self-selection bias reveals large survival benefits from delivering and treating VLBW infants at high-volume hospitals. This supports policies regionalizing the delivery and care for pregnancies at-risk for VLBW at high-volume hospitals.

The installation and extraction of jack-up spudcans may induce significant stresses in the adjacent piles supporting the permanent jacket platforms at an offshore site. In the present study, centrifuge model tests were conducted to investigate the effects of spudcan movements on the lateral and axial behaviour of adjacent fixed-head piles embedded in soft clay. Parameters such as jack-up operation period, clearance between the spudcan and pile, and the embedment length of the pile are examined. The test results show that the most critical period for platform piles is at the end of spudcan installation, and the lateral pile behaviour is more severely affected than the axial pile behaviour. During spudcan installation, the induced bending moment on a pile located one-quarter spudcan diameter away from the spudcan edge is about 2·4 times that of a pile located one spudcan diameter away. For a deeply buried spudcan with penetration of over three-quarters spudcan diameter, the induced bending moment on longer piles is much smaller than that on shorter piles. The experimental findings provide further insights into the underlying mechanisms governing spudcan–pile interaction in soft clay under various configurations and conditions.

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Weight-related school bullying and victimization have become important public health issues among adolescents around the world. This study aims to examine gender differences in the effects of Body Mass Index (BMI) on school bullying and victimization among secondary school students. This study conducted a survey among 2849 adolescents—1393 girls (48.9%) and 1456 boys (51.1%). The students were between 12 and 18 years of age and were recruited from ten secondary schools in 2019 in Suqian City in China. The study showed that overweight boys were more likely to bully others and be bullied by peers compared to normal weight boys. In contrast, overweight girls reported less bullying than normal-weight girls. No significant relationship was found between overweight and victimization among female students. The implications for comprehensive sexuality education practices are also discussed.

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