No abstract

Stereo rig with wide baseline is necessary when accurate depth estimation for distant object is desired. However, in order to make calibration pattern to be viewed from both left and right cameras, the wider the baseline the bigger the calibration pattern is required. In contrast to the traditional stereo calibration method using calibration pattern, we propose a self-calibration approach that can estimate cameras' rotation matrices for stereo rig with wide baseline (3 m). Given images taken from left and right cameras, the relative roll and pitch angles between two cameras are recovered by aligning sea horizon in left and right images. The pitch angle is estimated by making the projections of one point at infinite distance appear at the same location in both images. A photometric minimization is applied to refine the rotation parameters. Compared with conventional checkerboard-based calibration techniques which require extra equipments or personnel, our approach only needs a pair of sea images. Moreover, unlike most self-calibration approaches, feature detection and matching are not required which makes it possible to apply our approach on featureless images. As a result, it is flexible and easy to implement our approach on sea surface images. Real world experiments demonstrate the feasibility of our approach.

A real time vision based long range object detection and tracking algorithm for unmanned surface vehicles (USV) is proposed in this paper. HD image (2736 × 2192) is utilised in this work to obtain high accuracy for the object distance estimation. With handling such high resolution images for real time performance, we propose a coarse to fine approach, which firstly estimates the sea surface plane and locations of objects coarsely on lower resolution images corresponding to the HD images, then the detected coarse locations or regions of interest (ROI) are projected to the original HD image, finally stereo matching is preformed in the original image only on these extracted ROI, which renders more accurate 3D information for localizing the objects on the open sea. In the tracking, we propose to combine the target tracking based on 2D image with the constrained template matching to compute the depth, which demonstrates a more robust and accurate performance. Experimental results with our own dataset verify the high efficiency of our proposed method.

BackgroundEchovirus type 11(E-11) can cause fatal haemorrhage-hepatitis syndrome in neonates. This study aims to investigate clinical risk factors and early markers of E-11 associated neonatal haemorrhage-hepatitis syndrome.MethodsThis is a multicentre retrospective cohort study of 105 neonates with E-11 infection in China. Patients with haemorrhage-hepatitis syndrome (the severe group) were compared with those with mild disease. Clinical risk factors and early markers of haemorrhage-hepatitis syndrome were analysed. In addition, cytokine analysis were performed in selective patients to explore the immune responses.ResultsIn addition to prematurity, low birth weight, premature rupture of fetal membrane, total parenteral nutrition (PN) (OR, 28.7; 95% CI, 2.8–295.1) and partial PN (OR, 12.9; 95% CI, 2.2–77.5) prior to the onset of disease were identified as risk factors of developing haemorrhage-hepatitis syndrome. Progressive decrease in haemoglobin levels (per 10 g/L; OR, 1.5; 95% CI, 1.1–2.0) and platelet (PLT) < 140 × 10⁹/L at early stage of illness (OR, 17.7; 95% CI, 1.4–221.5) were associated with the development of haemorrhage-hepatitis syndrome. Immunological workup revealed significantly increased interferon-inducible protein-10(IP-10) (P < 0.0005) but decreased IFN-α (P < 0.05) in peripheral blood in severe patients compared with the mild cases.ConclusionsPN may potentiate the development of E-11 associated haemorrhage-hepatitis syndrome. Early onset of thrombocytopenia and decreased haemoglobin could be helpful in early identification of neonates with the disease. The low level of IFN-α and elevated expression of IP-10 may promote the progression of haemorrhage-hepatitis syndrome.

Using the childbearing survey data from Hubei Province in March 2022, this article empirically analyzed the status quo of fertility intention and its influencing factors among Chinese married youth during the COVID-19 pandemic. In our analysis, fertility intention was operationalized as the ideal number of children and short-term fertility plan. Statistical results showed that the average ideal number of children stood at 1.652, which was lower than the population replacement level, whilst only 16.4% of married youth had a short-term fertility plan. By utilizing a binary logit regression model and the sheaf coefficient technique, we found that COVID-19-induced factors (i.e., change in the marital relationship during the epidemic, delayed pregnancy preparation due to vaccination) had a more stable effect on fertility intention, especially on short-term fertility planning. Parenting perception characteristics exerted a great impact on the ideal number of children but a relatively small impact on short-term fertility planning. Meanwhile, married youth with stable jobs and a high family income did not necessarily show stronger fertility intentions than those with fewer socioeconomic resources. In addition, the findings also reveal that the relative importance of fertility-influencing factors could vary at different fertile stages, which have valuable implications for population policy in Chinese contexts.