Path Planning for Concentric Tube Robots: a Toolchain with Application to Stereotactic Neurosurgery

We present a toolchain for solving path planning problems for concentric tube robots through obstacle fields. First, ellipsoidal sets representing the target area and obstacles are constructed from labelled point clouds. Then, the nonlinear and highly nonconvex optimal control problem is solved by introducing a homotopy on the obstacle positions where at one extreme of the parameter the obstacles are removed from the operating space, and at the other extreme they are located at their intended positions. We present a detailed example (with more than a thousand obstacles) from stereotactic neurosurgery with real-world data obtained from labelled MPRI scans.Comment: 8 pages, 7 figures. Paper under revie

Risky sexual behaviours of high-school pupils in an era of HIV and AIDS

Objective. To identify risky sexual behaviours and demographic factors that place high-school pupils at risk of HIV and AIDS. Methods. A cross-sectional study was undertaken to explore factors influencing the sexual behaviour of high-school pupils (mean age 15.4 years; SD 1.11). Structured self-reported questionnaires were completed by all grade 10 pupils (N=805) at all the Wentworth, Durban, public high schools. Results. Significant gender differences in sexual practices were reported, such as males being more likely to engage in sexual activity than females (OR 4.92;

Predischarge transcutaneous bilirubin screening reduces readmission rate for hyperbilirubinaemia in diverse South African newborns: A randomised controlled trial

Background. In South Africa (SA), healthy term newborns are usually discharged ˂72 hours after delivery. Discharged babies remain at risk for severe hyperbilirubinaemia if it is not identified early. Hyperbilirubinaemia is an important cause of readmission, and also leads to neonatal mortality and morbidity. Use of transcutaneous bilirubin (TcB) screening before hospital discharge has been controversial.Objectives. To test the clinical benefits of TcB screening of healthy newborns before discharge for the outcomes of readmission for jaundice and severe hyperbilirubinaemia in a randomised controlled trial (RCT).Methods. This was a RCT. We compared predischarge TcB screening with visual assessment (alone) for jaundice in apparently healthy newborns at a public tertiary hospital in Cape Town, SA. Patients or study participants were not involved in the study design and implementation.Results. Of the 1 858 infants, 63% were black, 35% of mixed race and 1% white. There was a significant reduction in the rate of readmission for jaundice (risk ratio (RR) 0.25; 95% confidence interval (CI) 0.14 - 0.46; p<0.0001) and in the incidence of severe hyperbilirubinaemia (RR 0.27; 95% CI 0.08 - 0.97; p=0.05) with the use of TcB screening compared with visual inspection.Conclusions. Predischarge TcB screening is superior in identifying newborns at risk of severe hyperbilirubinaemia compared with visual inspection. We recommend that every newborn, regardless of skin pigmentation, should receive objective bilirubin screening before hospital discharge. Universal bilirubin screening in newborns could potentially reduce hyperbilirubinaemia-related morbidity and mortality

ExoMars Schiaparelli Direct-to-Earth Observation using GMRT

During the ExoMars Schiaparelli separation event on 16 October 2016 and Entry, Descent, and Landing (EDL) events 3 days later, the Giant Metrewave Radio Telescope (GMRT) near Pune, India, was used to directly observe UHF transmissions from the Schiaparelli lander as they arrive at Earth. The Doppler shift of the carrier frequency was measured and used as a diagnostic to identify key events during EDL. This signal detection at GMRT was the only real‐time aliveness indicator to European Space Agency mission operations during the critical EDL stage of the mission

ExoMars Schiaparelli Direct-to-Earth Observation using GMRT

During the ExoMars Schiaparelli separation event on 16 October 2016 and Entry, Descent, and Landing (EDL) events 3 days later, the Giant Metrewave Radio Telescope (GMRT) near Pune, India, was used to directly observe UHF transmissions from the Schiaparelli lander as they arrive at Earth. The Doppler shift of the carrier frequency was measured and used as a diagnostic to identify key events during EDL. This signal detection at GMRT was the only real‐time aliveness indicator to European Space Agency mission operations during the critical EDL stage of the mission

Model Predictive Control Tailored to Epidemic Models

We propose a model predictive control (MPC) approach for minimising the social distancing and quarantine measures during a pandemic while maintaining a hard infection cap. To this end, we study the admissible and the maximal robust positively invariant set (MRPI) of the standard SEIR compartmental model with control inputs. Exploiting the fact that in the MRPI all restrictions can be lifted without violating the infection cap, we choose a suitable subset of the MRPI to define terminal constraints in our MPC routine and show that the number of infected people decays exponentially within this set. Furthermore, under mild assumptions we prove existence of a uniform bound on the time required to reach this terminal region (without violating the infection cap) starting in the admissible set. The findings are substantiated based on a numerical case study.Comment: 14 pages, 3 figure

Micromanipulation at an infertility centre

Aim. Human in vitro fertilisation (IVF) and gamete intrafallopian transfer have been used in the management of various forms of infertility. In cases of severe male-factor infertility, fertilisation can be a factor. In this study micromanipulation was used to increase fertilisation in such cases.Methods. Two micromanipulation techniques, subzonal sperm injection (SUZI) and partial zona dissection (PZD), were used to assist fertilisation in patients with abnorTl)al semen parameters. Ten couples with severe oligo-, teratoand asthenozoospermia participated in the SUZI programme. Seventy-three oocytes were obtained from these 10 patients. PZD was used on day 1 oocytes in cases of male infertility as well as a rescue attempt on day 2 oocytes when fertilisation had failed after routine insemination.Results. The SUZI technique had a fertilisation rate of 37,7%. In this group, a biochemical pregnancy was achieved. Differences between the fertilisation rate of conventionallVF (33,3%) and PZD (56,3%) in cases of male infertility, were not statistically significant although a clinical difference could be detected. PZD was statistically effective in facilitating fertilisation (37,5% v. 8,3%) in couples where this procedure was introduced to reinseminate 24-hour-old unfertilised oocytes. Four patients received PZD reinseminated embryos. An average of 1,45 PZD embryos were replaced and 1 implantation pregnancy was confirmed.Conclusion. The micromanipulation results are encouraging arid seemed to increase the efficiency of IVF in humans. Furthermore, our data support the conclusion that micromanipulation procedures can bring about pregnancies