Stability Analysis of Negative Resistance-Based Source Combining Power Amplifiers

An investigation into the stability of negative resistance-based source combining power amplifiers is conducted in this thesis. Two different negative resistance-based source combining topologies, a series and parallel version, are considered. Stability is analyzed using a simple and intuitive broadband approach that leverages linear circuit stability criterion and two different linearization methods: linearization around the operating point and in the frequency domain. Using this strategy, it is shown that conditions for self-sustained oscillation exist for both topologies. For the series combining topology, self-sustained oscillation is prevented by means of injection locking

Pregnancy-Related Lumbopelvic Pain: Listening to Australian Women

Objective. To investigate the prevalence and nature of lumbo-pelvic pain (LPP), that is experienced by women in the lumbar and/or sacro-iliac area and/or symphysis pubis during pregnancy. Design. Cross-sectional, descriptive study. Setting. An Australian public hospital antenatal clinic. Sample population: Women in their third trimester of pregnancy. Method. Women were recruited to the study as they presented for their antenatal appointment. A survey collected demographic data and was used to self report LPP. A pain diagram differentiated low back, pelvic girdle or combined pain. Closed and open ended questions explored the experiences of the women. Main Outcome Measures. The Visual Analogue Scale and the Oswestry Disability Index (Version 2.1a). Results. There was a high prevalence of self reported LPP during the pregnancy (71%). An association was found between the reporting of LPP, multiparity, and a previous history of LPP. The mean intensity score for usual pain was 6/10 and four out of five women reported disability associated with the condition. Most women (71%) had reported their symptoms to their maternity carer however only a small proportion of these women received intervention. Conclusion. LPP is a potentially significant health issue during pregnancy

Vaccine intention and hesitancy among Australian women who are currently pregnant or have recently given birth : the Birth in the Time of COVID-19 (BITTOC) national online survey

Objective To examine the prevalence of COVID-19 vaccination, and factors associated with vaccination intention and hesitancy in pregnant and postnatal women in Australia. Design and setting A national online survey was conducted over 6 months between 31 August 2021 and 1 March 2022 and responses to vaccination status were categorised as: 'vaccinated', 'vaccine intended' and 'vaccine hesitant'. The data were weighted to reflect the proportion of women of reproductive age. Potential confounding variables were examined using multinomial logistic regression analyses, and all comparisons were made against vaccinated pregnant and postnatal women. Participants 2140 women responded to the survey (838 pregnant; 1302 recently post partum). Results Amongst pregnant women, 586 (69.9%) were vaccinated, 166 (19.8%) indicated intention and 86 (10.3%) were hesitant. In postnatal women, this was 1060 (81.4%), 143 (11.0%) and 99 (7.6%), respectively. Only 52 (6.2%) of pregnant women stated never wanting a COVID-19 vaccine. Vaccine hesitancy increased over time, and for pregnant women was associated with: living in a state other than New South Wales (NSW) (Adjusted Relative Risk (ARR) 2.77, 95%CI: 1.68-4.56 for vaccine intention and ARR=3.31, 95%CI: 1.52-7.20 for vaccine hesitancy), younger age <30 years, not having a university education, income <80K AUD, gestation <28 weeks, having no pregnancy risk factors, and being less satisfied with life (ARR=2.20, 95%CI: 1.04-4.65 for vaccine intention and ARR=2.53, 95%CI: 1.02-6.25 for vaccine hesitancy). For postnatal women: living in a state other than NSW or Victoria, income <80K AUD and having private obstetric care (ARR=2.06, 95%CI: 1.23-3.46) were significantly associated with vaccine hesitancy. Conclusions Around 1 in 10 pregnant women and just over 1 in 13 postnatal women reported vaccine hesitancy in this Australian survey, and hesitancy was higher in the latter 3-month period. Tailored messages to younger mothers and those from lower-middle socioeconomic groups, alongside advice from midwives and obstetricians, could help to reduce hesitancy among pregnant and postnatal women. Financial incentives may help to facilitate COVID-19 vaccine uptake. A real-time surveillance system and additional pregnancy fields added to the Australian immunisation register would support the safety monitoring of multiple vaccines in pregnancy and may build confidence

Mapping the trajectories for women and their babies from births planned at home, in a birth centre or in a hospital in New South Wales, Australia, between 2000 and 2012

Background: In New South Wales (NSW) Australia, women at low risk of complications can choose from three birth settings: home, birth centre and hospital. Between 2000 and 2012, around 6.4% of pregnant women planned to give birth in a birth centre (6%) or at home (0.4%) and 93.6% of women planned to birth in a hospital. A proportion of the woman in the home and birth centre groups transferred to hospital. However, their pathways or trajectories are largely unknown. Aim: The aim was to map the trajectories and interventions experienced by women and their babies from births planned at home, in a birth centre or in a hospital over a 13-year period in NSW. Methods: Using population-based linked datasets from NSW, women at low risk of complications, with singleton pregnancies, gestation 37–41 completed weeks and spontaneous onset of labour were included. We used a decision tree framework to depict the trajectories of these women and estimate the probabilities of the following: giving birth in their planned setting; being transferred; requiring interventions and neonatal admission to higher level hospital care. The trajectories were analysed by parity. Results: Over a 13-year period, 23% of nulliparous and 0.8% of multiparous women planning a home birth were transferred to hospital. In the birth centre group, 34% of nulliparae and 12% of multiparas were transferred to a hospital. Normal vaginal birth rates were higher in multiparous women compared to nulliparous women in all settings. Neonatal admission to SCN/NICU was highest in the planned hospital group for nulliparous women (10.1%), 7.1% for nulliparous women planning a birth centre birth and 5.1% of nulliparous women planning a homebirth. Multiparas had lower admissions to SCN/NICU for all thee settings (hospital 6.3%, BC 3.6%, home 1.6%, respectively). Conclusions: Women who plan to give birth at home or in a birth centre have high rates of vaginal birth, even when transferred to hospital. Evidence on the trajectories of women who choose to give birth at home or in birth centres will assist the planning, costing and expansion of models of care in NSW

Setting research priorities to improve global newborn health and prevent stillbirths by 2025

Acknowledgements: The authors thank the expert group for their time and effort in this priority–setting exercise, and the contribution of anonymous reviewers to the final version of this report. We acknowledge inputs from Dr Diane Morof from Centers for Disease Control and Prevention, USA. Funding: This work was supported by Save the Children.Peer reviewedPublisher PD

Women’s reasons for, and experiences of, choosing a homebirth following a caesarean section

BACKGROUND: Caesarean section is rising in the developed world and vaginal birth after caesarean (VBAC) is declining. There are increased reports of women seeking a homebirth following a caesarean section (HBAC) in Australia but little is known about the reasons for this study aimed to explore women's reasons for and experiences of choosing a HBAC. METHODS: Twelve women participated in a semi-structured one-to-one interview. The interviews were digitally recorded, then transcribed verbatim. These data were analysed using thematic analysis. RESULTS: The overarching theme that emerged was ‘It’s never happening again’. Women clearly articulated why it [caesarean section] was never happening again under the following sub themes: ‘treated like a piece of meat’, ‘I was traumatised by it for years’, ‘you can smell the fear in the room’, ‘re-traumatised by the system’. They also described how it [caesarean section] was never happening again under the sub themes: ‘getting informed and gaining confidence’, ‘avoiding judgment through selective telling’, ‘preparing for birth’, ‘gathering support’ and ‘all about safety but I came first’. The women then identified the impact of their HBAC under the subthemes ‘I felt like superwoman’ and ‘there is just no comparison’. CONCLUSIONS: Birth intervention may cause physical and emotional trauma that can have a significant impact on some women. Inflexible hospital systems and inflexible attitudes around policy and care led some women to seek other options. Women report that achieving a HBAC has benefits for the relationship with their baby. VBAC policies and practices in hospitals need to be flexible to enable women to negotiate the care that they wish to have

Setting research priorities to improve global newborn health and prevent stillbirths by 2025.

BACKGROUND: In 2013, an estimated 2.8 million newborns died and 2.7 million were stillborn. A much greater number suffer from long term impairment associated with preterm birth, intrauterine growth restriction, congenital anomalies, and perinatal or infectious causes. With the approaching deadline for the achievement of the Millennium Development Goals (MDGs) in 2015, there was a need to set the new research priorities on newborns and stillbirth with a focus not only on survival but also on health, growth and development. We therefore carried out a systematic exercise to set newborn health research priorities for 2013-2025. METHODS: We used adapted Child Health and Nutrition Research Initiative (CHNRI) methods for this prioritization exercise. We identified and approached the 200 most productive researchers and 400 program experts, and 132 of them submitted research questions online. These were collated into a set of 205 research questions, sent for scoring to the 600 identified experts, and were assessed and scored by 91 experts. RESULTS: Nine out of top ten identified priorities were in the domain of research on improving delivery of known interventions, with simplified neonatal resuscitation program and clinical algorithms and improved skills of community health workers leading the list. The top 10 priorities in the domain of development were led by ideas on improved Kangaroo Mother Care at community level, how to improve the accuracy of diagnosis by community health workers, and perinatal audits. The 10 leading priorities for discovery research focused on stable surfactant with novel modes of administration for preterm babies, ability to diagnose fetal distress and novel tocolytic agents to delay or stop preterm labour. CONCLUSION: These findings will assist both donors and researchers in supporting and conducting research to close the knowledge gaps for reducing neonatal mortality, morbidity and long term impairment. WHO, SNL and other partners will work to generate interest among key national stakeholders, governments, NGOs, and research institutes in these priorities, while encouraging research funders to support them. We will track research funding, relevant requests for proposals and trial registers to monitor if the priorities identified by this exercise are being addressed

Setting research priorities to improve global newborn health and prevent stillbirths by 2025

Background In 2013, an estimated 2.8 million newborns died and 2.7 million were stillborn. A much greater number suffer from long term impairment associated with preterm birth, intrauterine growth restriction, congenital anomalies, and perinatal or infectious causes. With the approaching deadline for the achievement of the Millennium Development Goals (MDGs) in 2015, there was a need to set the new research priorities on newborns and stillbirth with a focus not only on survival but also on health, growth and development. We therefore carried out a systematic exercise to set newborn health research priorities for 2013-2025. Methods We used adapted Child Health and Nutrition Research Initiative (CHNRI) methods for this prioritization exercise. We identified and approached the 200 most productive researchers and 400 program experts, and 132 of them submitted research questions online. These were collated into a set of 205 research questions, sent for scoring to the 600 identified experts, and were assessed and scored by 91 experts. Results Nine out of top ten identified priorities were in the domain of research on improving delivery of known interventions, with simplified neonatal resuscitation program and clinical algorithms and improved skills of community health workers leading the list. The top 10 priorities in the domain of development were led by ideas on improved Kangaroo Mother Care at community level, how to improve the accuracy of diagnosis by community health workers, and perinatal audits. The 10 leading priorities for discovery research focused on stable surfactant with novel modes of administration for preterm babies, ability to diagnose fetal distress and novel tocolytic agents to delay or stop preterm labour. Conclusion These findings will assist both donors and researchers in supporting and conducting research to close the knowledge gaps for reducing neonatal mortality, morbidity and long term impairment. WHO, SNL and other partners will work to generate interest among key national stakeholders, governments, NGOs, and research institutes in these priorities, while encouraging research funders to support them. We will track research funding, relevant requests for proposals and trial registers to monitor if the priorities identified by this exercise are being addressed