Background Human immunodeficiency virus (HIV) sero-prevalence rate during pregnancy was 26% in 2009 in Gauteng. HIV exposure is associated with high morbidity and mortality in infants. Few studies have assessed the effect of HIV exposure on morbidity and mortality in very low birth weight (VLBW) infants. Aim To determine the infant characteristics at birth, morbidity during hospital stay and mortality at hospital discharge of VLBW infants according to maternal HIV status. Methods This was a retrospective cross sectional descriptive study. Hospital records of VLBW infants admitted at the Chris Hani Baragwanath Academic Hospital, Division of Neonatology from 1st January 2011 to 30th June 2011 were reviewed. Data were collected in an Excel spread sheet and imported to STATA version 12 for analysis. Results 302 hospital records of VLBW infants admitted from January to June 2011 were retrieved and reviewed. About a third (34.1%) of VLBW infants were born to mothers who were HIV positive. There were more babies who weighed <1000 grams in the HIV-exposed infants compared to HIV-unexposed infants (p-0.001). HIV exposed infants had a smaller head circumference (p-0.003), a shorter body length (p-0.006) and significantly more severe grades of IVH (p <0.001) compared to HIV unexposed infants. The overall mortality rate in VLBW infants was 27%, with HIV exposed infants having a mortality rate of 38.6% compared to 21% in the HIV-negative infants (p-0.002). Multivariate analysis showed that the main predictor of mortality was birth weight (p<0.001). Conclusion Though on univariate analysis maternal HIV status was associated with mortality in VLBW infants, this effect was not found on multivariate analysis. Therefore the final conclusion from this study is that maternal HIV status has no independent effect on outcomes to hospital discharge in VLBW infants. Birth weight was the predictor of survival in VLBW infants.

Une des priorités scientifiques justifiant la construction de télescopes géants (classe 30-50m) est l'étude des premières générations de galaxies situées à de très grands décalages vers le rouge (1

Dissertation for MMed (Obstetrics and Gynaecology) and FCOG Part II / Hypertensive disorders in pregnancy are common and their incidence appears to be on the increase. Preeclampsia is a multi-organ, heterogeneous disorder of pregnancy associated with significant maternal, fetal and neonatal morbidity and mortality. Because preeclampsia is a progressive disorder, invariably delivery remote from term is often necessary to halt disease progression to benefit the mother and fetus. Objectives:  To determine the maternal outcomes in women with severe preeclampsia  To determine fetal and neonatal outcomes of infants born preterm Methods This was a prospective, descriptive study performed in three academic hospitals affiliated to the University of the Witwatersrand in Johannesburg. Data was collected from women with severe preeclampsia, who delivered between gestational ages of 26 weeks and 33 weeks, with a minimum neonatal weight of 500g as determined by sonography. Results: In the sample of 92 patients enrolled, there were two maternal deaths as a result of severe preeclampsia. Eclampsia and HELLP syndrome were the most frequently observed maternal complications at 34% and 49% respectively. Caesarean section was the most frequent method used to expedite delivery in 84% of women. Of the 97 babies delivered, 20% were confirmed intra-uterine fetal deaths, 7% demised during the early neonatal period and a there was a 40% very low birth weight rate. Conclusion: Despite interventions to reduce maternal and neonatal morbidity and mortality in our setting, our outcomes are similar to those observed in other parts of the world.

As the capacity for saving smaller and smaller infants increases, the ethical dilemmas experienced by neonatal nurses who care for the smallest and most fragile of human beings will also increase. The current approaches to the resuscitation and management of extremely premature infants (24 weeks gestation and less) has resulted in the survival of infants with far less than optimal outcome. Neonatal nurses have begun to question saving the lives of extremely premature infants just because the technology exists to do so. This study explores the ethical issues faced by neonatal nurses caring for infants of 24 weeks gestation and less. The research question arose out of the need for neonatal nurses to articulate the ethical issues that they face in clinical practice when caring for extremely premature infants. The study design takes a dual approach to the research question, namely, a survey questionnaire and a qualitative analysis informed by phenomenology. Given the complexities of the issues within the topic, this combination of methods was deemed to be the most appropriate in gaining a convincing and authentic result. The results of this research are not generalisable to the experience of other nurses, or nurses caring for other groups of premature infants. In the first stage of the study neonatal nurses, members of the Australian Association of Neonatal Nurses (ANNA), were surveyed using a self-completion questionnaire. Then, in the qualitative component of this study fourteen (14) interviews with neonatal nurses were undertaken. These were either single or focus group interviews. In all, twenty four neonatal nurses from the state of New South Wales (NSW) and the Australian Capital Territory (ACT) were interviewed about their experiences of caring for infants of 24 weeks gestation and less. The questions asked during the interviews were based on findings from the questionnaire. The interview data was analysed using a qualitative approach informed by interpretative phenomenology. The qualitative analysis revealed that the ethical dilemmas faced by the nurses existed within four themes. The four themes are: • It’s all about this baby • Having a voice • Dealing with awfulness • Reflecting on the outcome. The qualitative description as given in the four themes reveals structures and meanings about what it is to be the neonatal nurse who experiences ethical dilemmas when caring for extremely premature infants. The study and its findings are a written account of the experiences of neonatal nurses and their ethical dilemmas in caring for infants of 24 weeks gestation and less. The meanings within the nurses’ experiences are offered and the final phenomenological description, Balancing hope with reality, is given. Hope has a buffering effect on the nurses. The nurses inspire and instil hope in themselves and a baby’s parents until the reality of a poor outcome dawns. Each time an extremely premature baby is born the nurses are hopeful for a good outcome, but the reality is that they have experienced many instances in which babies die or have a poor outcome. The neonatal nurses, affected by their experiences of ethical distress, attempted to find a pathway to achieve a balance between their emotions and caring for the baby. In doing so the nurses were able to remain productive the neonatal intensive care unit, and give high quality care to the baby and compassion to the parents. This study makes an important contribution to neonatal nursing knowledge and practice by exploring the ethical dilemmas and complexities associated with extremely premature infants. This study also makes a unique contribution to the body of literature on ethical dilemmas experienced by neonatal nurses.

This dissertation describes the design, analysis and testing of an unconventional rotor featuring extremely flexible, retractable blades. These rotor blades are composed of a flexible matrix composite material; they are so flexible that they can be rolled up and stowed in the rotor hub. The motivation for this study is to equip the next generation of unmanned rotary-wing vehicles with morphing rotors that can change their diameter in flight, based on mission requirements. Due to their negligible structural stiffness, the static and dynamic behavior of these blades is dominated by centrifugal effects. Passive stabilization of the flexible blades is achieved by centrifugal stiffening in conjunction with an appropriate spanwise and chordwise mass distribution. In particular, such blades are susceptible to large deformations. For example, a combination of the trapeze effect and the tennis racquet effect induces a large negative twist that results in decreased efficiency. Additionally, the rotor blades are prone to aeroelastic instabilities due to their low rotating torsional frequency, and it is seen that without careful design the blades experience coupled pitch-flap limit cycle oscillations. The primary focus of this research is to develop analytical and experimental tools to predict and measure the deformations of an extremely flexible rotor blade with non-uniform mass distribution. A novel aeroelastic analysis tailored towards unconventional blades with negligible structural stiffness is developed. In contrast to conventional analyses developed for rigid rotor blades, the present analysis assumes very large elastic twist. The nonlinear coupled equations of motion for the flap bending, lead-lag bending and torsion of an elastic rotating blade are derived using Hamilton's principle. The virtual work associated with unsteady aerodynamic forces in hover is included in the analysis. An ordering scheme consistent with the relevant physical quantities is defined and terms up to second order are retained in the Hamiltonian. The equations of motion are solved using a nonlinear finite element analysis. The steady-state deformation of the rotor blade is obtained from the time invariant part of the solution. The rotating flap, lag and torsional frequencies are found by solving the eigenvalue problem associated with the homogeneous system of equations. Finally, stability boundaries are computed for various operating conditions and the influence of parameters such as rotational velocity and collective pitch angle is discussed. The analytical predictions are validated by experimental measurements of the blade deformation in hover. These measurements are obtained by a novel, non-contact optical technique called three-dimensional Digital Image Correlation (3D DIC). The use of this technique is demonstrated for the first time to obtain full-field deformation measurements of a rotating blade. In addition, stability boundaries are extracted from experimental observations and correlated with predictions. / text

Collection of sewage from toilets in a closed tank provides good protection for the environment and health. The closed tank reduces emissions of fertilizing substances, and other substances that may pose a risk, such as pathogens and drug residues. To reduce the water volume in the tank, it is advantageous to connect an extremely low-flush toilet, which means that the average flush volume is a maximum of 1 liter per flush. It is important that the toilet system is reliable for the technology to be used to a greater extent. This study examines experiences and functioning of extremely low-flush toilets to identify possible deficiencies and possible areas for improvement. Information has been obtained through telephone interviews and online surveys. The result shows that most respondents are generally satisfied with their extremely low-flush toilets. For the system to function optimally, it must be properly installed and maintained. There are some deficiencies that are more common, such as interruptions caused by flushing of incorrect objects or incorrect installation, but also some occasional errors. Many malfunctions appear to be caused by improper use or installation. There may be a need to develop certain technology components, such as the alarm function. The sound when flushing can be perceived as too loud. It is important that there are clear instructions for installation, maintenance, and use, as well as functioning service networks in case of problems.

No description available.

The Sherman Morrison iteration method is developed to solve regularized least squares problems. Notions of pivoting and splitting are deliberated on to make the method more robust. The Sherman Morrison iteration method is shown to be effective when dealing with an extremely underdetermined least squares problem. The performance of the Sherman Morrison iteration is compared to classic direct methods, as well as iterative methods, in a number of experiments. Specific Matlab implementation of the Sherman Morrison iteration is discussed, with Matlab codes for the method available in the appendix. / Master of Science

L'Europe prépare actuellement le plus grand télescope du monde : l'European Extremely Large Telescope (E-ELT). Prévu vers 2026, ce télescope géant permettra de répondre à des questions fondamentales de l'astrophysique contemporaine. L'imagerie d'objets astrophysiques depuis des télescopes au sol est cependant perturbée par l'atmosphère qui réduit la capacité des instruments au sol à distinguer les objets proches. L'Optique Adaptative (OA) permet de restaurer cette résolution angulaire en corrigeant en temps réel (via un miroir déformable) le front d'onde perturbé par l'atmosphère (mesuré par l'Analyseur de Surface d'Onde (ASO)). Jusqu'à récemment, la majorité des systèmes d'OA utilisaient des ASO Shack-Hartmann (SH). Des concepts concurrents basés sur le filtrage optique de Fourier (le senseur Pyramide ou l'analyseur Zernike) viennent cependant d'être mis en fonctionnement et leurs résultats semblent surpasser les performances du SH. En vue de leur potentielle utilisation sur les ELTs, cette thèse vise à consolider leur compréhension théorique ainsi qu'à optimiser ces ASO basés sur le filtrage de Fourier. Cette thèse développe un cadre mathématique qui décrit sous un unique formalisme ces ASO. Il permet de généraliser les designs préexistants -passant ainsi d'ASO uniques à des "classes d'ASO"- en transformant leurs grandeurs caractéristiques à l'origine fixées en degrés de liberté. Les classes Pyramide et Zernike sont donc explorées dans le but d'optimiser ces ASO au regard des attentes expérimentales. Des configurations inédites de la classe Pyramide -ASO que l'on appelle Pyramides aplaties- s'avèrent notamment prometteuses et font l'objet d'une étude plus poussée. / Europe is currently preparing the largest telescope of the world: the European Extremely Large Telescope (E-ELT). Planned by 2026, this huge telescope will allow to answer fundamental questions of contemporary astrophysics. However, images of astrophysical objects done by ground based telescopes suffer from the atmospheric turbulence which reduces the capacity of instruments to distinguish objects too close to each other. The Adaptive Optics (AO) allows to restore this loss of angular resolution by correcting (thanks to a deformable mirror) in real time the perturbed wave front (measured by the WaveFront Sensor (WFS)).Until very recently, the majority of AO systems had used the Shack-Hartmann (SH) WFS. New concepts based on Fourier filtering (the Pyramid or the Zernike WFSs) have however just been put in operation in several professional observatories and their results seem to outperform the SH. Since they would potentially be chosen for the AO systems of the future ELTs, this thesis aims to consolidate their theoretical understanding and to optimize these Fourier based WFSs.We firstly develop a mathematical framework which describes all these WFSs under an unique formalism. It allows to generalize the pre-existent designs -a WFS thus becomes a "WFS class"- by considering their optical parameters as flexible quantities. We then explored the two Pyramid and Zernike classes to identify the influence of class' parameters on performance criteria in order to optimize optical designs with regard to the instrumental requirements. New configurations of the Pyramid class -that we called Flattened pyramids- show promising behaviors and are studied in details.

[pt] Devido às exigências da largura de banda, especialmente nas comunicações sem fios que são cada dia maiores pelo aumento do numero de usuários, é necessário estudar a banda de EHF(Extremely High Frequency). A transmissão e recepção de dados em EHF constitui uma possível solução para aliviar a escassez do espectro e satisfazer a crescente demanda de maiores velocidades tentado resolver as limitações dos sistemas atuais. As ondas de radio na banda EHF vão de 30 até 300 GHz e são chamadas ondas milimétricas, já que seus comprimentos de onda vão de 10 mm até 1 mm. Neste trabalho, a montagem de um sistema de geração e detecção de ondas de EHF a partir do batimento de dois lasers é apresentada. Técnicas de modulação e demodulação em fase, amplitude e frequência na faixa de 200-300 GHz são demonstradas. / [en] The capacity of wireless communications has started to reach the top and the unstoppable increase of users is becoming a problem because more bandwidth is needed, which has gave rise to the study of EHF (Extremely High Frequency) band. Transmission and reception of data in EHF is shown as a solution to alleviate the scarcity of the spectrum and to meet the request of faster speeds to solve the limitation of the actual systems. The range of radio waves in EHF band go from 30 to 300 GHz, and are called millimeter waves since their wavelengths are between 10mm and 1mm. In this work is presented a system capable to generate and detect EHF waves from the beating of two lasers, and at the same time different modulation and demodulation techniques (phase, amplitude and frequency) are presented.