All future Extremely Large Telescopes (ELTs) will be segmented. However, as their size grows, they become increasingly sensitive to external disturbances, such as gravity, wind and temperature gradients and to internal vibration sources. Maintaining their optical quality will rely more and more on active control means. This thesis studies active optics of segmented primary mirrors, which aims at stabilizing the shape and ensuring the continuity of the surface formed by the segments in the face of external disturbances. The modelling and the control strategy for active optics of segmented mirrors are examined. The model has a moderate size due to the separation of the quasi-static behavior of the mirror (primary response) from the dynamic response (secondary, or residual response). The control strategy considers explicitly the primary response of the telescope through a singular value controller. The control-structure interaction is addressed with the general robustness theory of multivariable feedback systems, where the secondary response is considered as uncertainty. Scaling laws allowing the extrapolation of the results obtained with existing 10m telescopes to future ELTs and even future larger telescopes are addressed and the most relevant parameters are highlighted. The study is illustrated with a set of examples of increasing sizes, up to 200 segments. This numerical study confirms that scaling laws, originally developed with simple analytical models, can be used in confidence in the preliminary design of large segmented telescopes.

Background: Improved neonatal care has resulted in an increasing population of surviving infants. Neonatal morbidity in preterm infants is, however, high, and retinopathy of prematurity (ROP) is one of the major neonatal morbidities. Observations have suggested that ROP might have a different course in extremely preterm compared to more mature infants. Aims: To study the incidence, natural history and treatment of the disease, and the implications regarding screening recommendations for the population of extremely preterm infants. Methods: A national, population-based study of neonatal morbidity in infants born before 27 gestational weeks was performed in Sweden during 2004 to 2007. ROP screening started in the 5th postnatal week and continued until the retina was completely vascularized. Results: Of the 506 infants surviving until the first ROP examination, 73% developed ROP; 38% mild ROP and 35% severe ROP. Ninety-nine infants (20%) were treated. A log-linear relationship was found between severe ROP and gestational age (GA) at birth, and the risk of ROP was reduced by 50% for each week of increase in GA at birth (Paper I). Postmenstrual age (PMA) at onset of ROP was significantly related to GA at birth, as was the site of onset of ROP. ROP had a predilection to start in the nasal retina in the most immature infants. There were significant relations between PMA at onset of ROP and severity of ROP as well as between the site of onset of ROP and severe ROP (Paper III). The most immature infants had a higher risk of reaching treatment criteria for ROP, a higher risk of progression from ROP 3 to treatment criteria, and they reached these criteria at an earlier PMA than the less immature infants (Paper II). According to our results, the first examination can be postponed until a PMA of 31 weeks in infants born before 27 weeks of gestation, since onset of ROP 3 did not occur before this age, and criteria for treatment were not reached before 32 weeks. The majority of infants (75%) were treated during a limited period, i.e. before a PMA of 39 weeks (Paper IV).

In this thesis, a novel fully self-aligned bulk-Si device named dual-channel source/drain-tied (DC-SDT) MOSFET with extremely thin (ET) body is proposed. The process utilizes the multiple epitaxial growths of SiGe/Si layers, so the starting material is bulk-Si wafer instead of the SOI wafer. We have investigated the RF/analog performance, and the high temperature induced device stability degradation has also been also investigated. Moreover, we have compared this structure with the other similar transistors such as: body-tied MOSFET (DC-BT MOSFET) and conventional dual-channel MOSFET (DC-SOI MOSFET). Based on the simulation results, for the DC-BT MOSFET, our proposed DC-SDT MOSFET has improved the device performances such as: Ioff decreased 47.6%, switching speed increased 18.1%, S.S. improved 13%, and voltage gain increased 25%. Whereas for the DC-SOI MOSFET, our proposed DC-SDT MOSFET has also improved the device performances such as: Ion increased 11.3%, reduction of lattice temperature 35.7% and 35.5 in the top and bottom channels, voltage gain increased 15%. We not only compared with the above two similar transistors, but also compared to the other mainstream devices, such as: FinFET and Gate-all-around. After the comparisons, we confirm that the proposed DC-SDT MOSFET has better ON-state current and short-channel behaviors. For the scaling, DC-SDT MOSFET can truly become one of the strong candidates.

Background/Aim: During the past two decades, major advances in maternal-fetal medicine, neonatology, and the development of regionalized perinatal care have resulted in dramatic increases in survival rates, by more than 60%, of extremely immature (EI) infants born at less than 26 completed weeks of gestation, creating a new infant population. Studies of school-age outcomes in children with an extremely low birth weight of < 1000 g, born in the1980s, indicated that these children had a substantially high prevalence of low-severity neuropsychological deficits, behavioral problems, and difficulties at school. Information on school-age outcomes of extremely preterm children born in the 1990s is sparse, and mainly restricted to the neurobehavioral and developmental outcome. The aim of this research was to investigate the comprehensive neurological, developmental, functional, and mental health status and health care needs of children born at 23-25 weeks of gestation in the 1990s, allowing a total view of the child in the context of the family, his peers, school, and the health care system. The ultimate aim was to obtain a clearer understanding of the functional capacities of these vulnerable children and the possibilities of ameliorative interventions, as a basis for planning and provision of services for this growing population. Methods: We studied 11-year-old children born from 1990 through 1992 before 26 completed weeks of gestation in all of Sweden. All had been evaluated at a corrected age of 36 months. Of 89 eligible children, 86 (97%) were studied at a mean age of 11 years. An equal number of children born at term served as controls. The following methods were used: 1) well validated, mailed questionnaires filled out by the parents, class teachers and the children themselves; 2) structured interviews were conducted with a parent or a primary caregiver; 3) review of pediatric case records and records from other specialist health care services; and 4) anthropometric measurements (length, weight, head circumference and body mass index) from birth to 11 years of age. The following domains were explored: current health status, growth attainment, mental health assessment, emotional well-being, adaptive functioning and social competencies, school performance, executive functions, and learning and language skills. Relations of socioeconomic background and of environmental and perinatal risk factors to the long-term outcome were evaluated. Results: EI children compared with the controls had significantly higher rates of specific diagnoses or disabilities including neurosensory impairment (15% vs 2%, respectively), asthma (20% vs 6%), poor motor skills (26% vs 3%), poor visual perception (21% vs 4%), poor learning skills (27% vs 3%),poor adaptive functioning (42% vs 9%), and poor academic performance (49% vs 7%). As a consequence of these disabilities, significantly more EI children than controls had chronic conditions, which included functional limitations (64% vs 11%), compensatory dependency needs (59% vs 25%), and services above those routinely required by children in general (67% vs 22%). Regarding growth attainment, EI children had significantly lower values for all three growth parameters (length, weight and head circumference) than the controls at 11 years. They showed a sharp decline in weight and height z scores up to 3 months’ corrected age, followed by good catch-up growth in both weight and height up to 11 years. EI children did not exhibit catch-up growth in head circumference after the first 6 months of life. Preterm birth and parental height were significant predictors of 11-year height, and group status (prematurity) correlated strongly with head circumference. Our results also suggest that the EI children had a significantly greater risk for poorer mental health and poorer emotional well-being than the control participants, including internalizing (anxiety/depression, withdrawn behavior and somatic complaints), and attention, social, and thought problems. No differences in externalizing problems were found between the EI cohort and controls. Multivariable analyses disclosed a number of significant predictors of behavioral adjustment: group status (EI vs control), family function, social risk, male gender, and presence of a chronic medical condition. Concerning school performance, more than half (59%) of our EI cohort were experiencing school difficulties and 15%, compared with 5% of the control children were attending special schools or having full-time special education. Despite fewer adaptive skills in the EI cohort these children were not different from the controls in respect to being happy and being positively adjusted in their day-to-day life. Compared with controls, EI children had a significantly increased risk for executive dysfunctions in most of the areas assessed (Attention control and Attention switching, Hypoactivity, Planning/organizing, and Working memory). EI children were also at increased risk for deficient skills in language tasks (comprehension, communication, and expression) and in the four standard measures of learning skills (reading/writing, math, general learning, and coping in learning). However, only a relatively small number of EI children exhibited severe impairments in executive or non-executive skills. Multivariate analyses revealed that prematurity, executive dysfunction and male gender were associated with poor learning skills. Conclusions and implications: Children born extremely immature have significantly greater health problems and special health care needs that require ongoing services through the school years. However, it is notable that very few children have severe impairments that curtail major activities of daily living. The overall results of this study are reassuring. Despite having an increased risk for mental health problems, executive dysfunctions and school difficulties, 85% of the EI children were in the mainstream schools and a majority were not having major adjustment difficulties. In terms of growth, most of our EI children showed good catch-up in late childhood and were within 2SD of their mean midparental height at 11 years of age. Although biological immaturity is associated with an increased risk for a substantial number of behavioral/emotional problems, improvement of the modifiable environmental factors will benefit the outcome in EI children. We also believe that knowledge of the course of development of psychopathological conditions from early childhood to adolescence and beyond is crucial for identifying the need for intervention and prevention strategies. Thus when there is evidence to suggest neuropsychological and behavioral or emotional problems, early identification and preventive measures might help families to manage these from an early stage. Our findings further suggest that current preterm follow-up programs might benefit from the addition of psychological and family services to traditional neurodevelopmental assessments, especially in the neonatal period and first years of life.

The aim of this project was to develop a passive optical compensating arrangement that would allow the formation and continued stability of interference patterns over a long timescale and also to investigate optical wave scattering in thick gratings at extreme angles of scattering. A novel passive arrangement based on a Sagnac interferometer is described that produces interference patterns more stable than those produced by a conventional arrangement. An analysis of the arrangement is presented that shows it to be an order of magnitude more stable than an equivalent conventional approach. The excellent fringe stability allowed holographic gratings with small periods (~ 0.5 μm) to be written in photorefractive lithium niobate with low intensity writing fields (~mW/cm2) produced by a He:Ne laser, despite long grating fabrication times (~ 1000 s). This was possible because the optical arrangement compensated for phase shifts introduced by translational and rotational mirror motion caused by environmental perturbations. It was shown that the rapid introduction of a phase shift in one of the writing fields can change the direction of energy flow in the two-wave mixing process. It was found that the improvement in stability of the modified Sagnac arrangement over a conventional interferometer decreased when the crossing angle was increased and that the point about which the mirrors are rotated greatly affects the stability of the arrangement. For a crossing angle of 12 degrees, the modified Sagnac arrangement is more than twice as stable when the mirrors are rotated about their midpoints, rather than their endpoints. Investigations into scattering in the extremely asymmetrical scattering (EAS) geometry were undertaken by scattering light from a 532nm Nd:YAG laser off gratings written in photorefractive barium titanate and lithium niobate. Despite the difficulties posed by background noise, there was very good agreement between the observed scattered field and that predicted by a previously established theoretical model. Thus, this work represents the first experimental observation of EAS in the optical part of the spectrum.

<b>Background:</b> The survival rate of preterm children has risen steadily due to advances in obstetric and neonatal intensive care. Children born extremely preterm (&le;28 weeks of gestation) are at high risk of long term developmental problems, including cerebral palsy, motor and cognitive impairment, visual and auditory deficits and behavioural problems. This can have serious implications for their quality of life and that of their family and carers. These children take up a disproportionate amount of neonatal intensive care unit resources and overall costs, and as they grow up are more likely to require additional health and social care services beyond routine care to compensate for their functional limitations. The early identification and management of factors that mediate long term outcome is necessary to assist healthcare professionals in selecting appropriate treatment pathways, and to develop, target and evaluate interventions. Many risk factor analyses for neurodevelopmental impairment have been published in preterm populations, but this vast literature has not been formally summarised. Furthermore, there is a dearth of studies reporting longitudinal analysis of neurodevelopmental trajectories from early childhood to adulthood. <b>Objectives:</b> The first aim of this thesis was to perform a comprehensive systematic review of the world literature over the last two decades, to consolidate the evidence about the prognosis of neurodevelopmental outcome in children born very preterm or with very low birth weight. The second aim was to conduct a longitudinal analysis of a cohort of extremely preterm participants followed up into early adulthood to investigate the trajectories of long term sequelae over time, and to examine the association of neurodevelopmental course in relation to the predictive factors identified in the systematic review. <b>Methods:</b> A systematic review was conducted using MEDLINE, EMBASE and PyscINFO databases to identify studies published between January 1 1990 and June 1 2014 reporting multivariable prediction models for the neurodevelopment of children born &le;32 weeks of gestation or with a birth weight &le;1250 grams (protocol registration number CRD42014006943). Seventy-eight studies reporting 222 risk factor models for neurodevelopmental outcome were identified. Two independent reviewers extracted key information about study design, outcome definition, risk factor selection, model development, reporting, and conducted a risk of bias assessment. To address the second objective of the study, a longitudinal analysis of cognitive and behavioural trajectories was conducted using a prospective, population-based cohort study in the United Kingdom and the Republic of Ireland. Three hundred and fifteen surviving infants born less than 26 completed weeks of gestation recruited at birth in 1995 and 160 term-born classroom peers recruited at age six were followed-up to 19 years. Participants were invited for up to four standardized, blinded cognitive assessments and the parent-completed Strengths and Difficulties Questionnaire was used to assess behavioural problems. <b>Results:</b> The systematic review of risk factors for motor impairment in children born very preterm or with very low birth weight provided strong evidence that neonatal brain injury is a robust prognostic factor for cerebral palsy, and some evidence that the use of postnatal steroids increases the risk and the use of antenatal steroids reduces the risk of cerebral palsy. There was moderate evidence that male sex was prognostic for motor impairment at school age in children free of major disability. The systematic review of risk factors for cognitive impairment identified male sex, non-white ethnicity, lower levels of parental education and lower birth weight as significant predictors of global cognitive dysfunction in early infancy, with parental education having a sustained impact after five years of age. There was also evidence that male sex was predictive of delayed language development in early infancy. Gestational age was found to be of limited use as prognostic factor for cerebral palsy, motor and cognitive impairment in cohorts restricted to &le;32 weeks of gestation. There was a dearth of good quality studies investigating risk factors for behavioural problems and psychiatric disorders and the findings of this review were inconclusive. The only factors that appeared to be consistent predictors of general behavioural problems were markers of socio-economic deprivation, neurodevelopmental or cognitive delay, and an abnormal behavioural screen in early infancy. In the longitudinal analysis of the prospective, population-based cohort of extremely preterm children, cognitive trajectories were stable in both the extremely preterm and term-born groups over time with persistent deficit in the extremely preterm group of 25.2 IQ points (95&percnt; CI: -27.8 to -22.6, p&LT;0.001) and only minimal catch-up over time. Participants with neonatal brain injury and of male sex had the largest deficits, but a lower level of maternal education and earlier gestational age at birth were also associated with reduced IQ scores. Behavioural problems were also more prevalent among the extremely preterm participants who had a mean Total Difficulties Score of 4.81 points above their term-born peers (95&percnt; CI: 3.76 to 5.87, p&LT;0.001) and which persisted over the time period. Behavioural difficulties were mainly due to hyperactivity, inattention and peer problems and were strongly associated with a positive behavioural screen in early infancy. <b>Conclusions:</b> The most robust predictors of poor neurodevelopmental outcome identified by the systematic review were neonatal brain injury, male sex, and markers of social disadvantage. The unclear findings for many risk factors may reflect differences in study design, study population, methodological quality and lack of standardization of measures. Or it may simply reflect the fact that prognostic modelling in such a heterogeneous population is challenging and complex, with multiple risk factors acting sequentially over time, and often with the existence of multiple impairments within the same individual. The main conclusions from the longitudinal analysis of children born extremely preterm is that being born too soon appears to place limits on brain plasticity and function which is not recovered over time; with the most vulnerable being males and those with evidence of brain injury early in life. These structural abnormalities may disturb neurodevelopmental processes and impede the brain from maintaining a normal developmental trajectory. If extremely preterm children fail to achieve optimum levels of cognitive function and are still experiencing behavioural problems once they have reached maturity, then this has implications for health and well-being in later adulthood and old age. Cognitive test scores in infancy and early childhood reflect early adult outcomes and a positive behavioural screen in infancy is strongly associated with early adult behavioural outcomes. <b>Recommendations:</b> The systematic review revealed some shortcomings in methodology and reporting that could be improved in future studies, and confirmed that that there is a dearth of properly designed and well-conducted prognostic modelling studies in this field. The findings and recommendations of this critical review should be used as a basis for the design, analysis and reporting of future studies seeking to develop multivariate risk factor or prognostic models in this population. There is an urgent need for larger population cohorts followed up routinely beyond two years as subtle outcomes such as impairment of executive function and fine motor skills cannot be reliably assessed at this age, and the natural course of some disorders may have their onset later in childhood. / Studies with larger sample sizes and greater power are needed for studying less common conditions in preterm populations and there should be more standardisation of outcome and risk factor measurements, particularly with the use of standard diagnostic evaluations to assess psychiatric disorders. Future studies should include a term-born comparison group and adopt appropriate statistical analysis techniques to analyse longitudinal outcome data and the impact of risk factors on these trajectories. Additional research is required to improve the prediction of individual differences, and to identify the neuropathological differences underlying different developmental trajectories and their interaction with environmental influences over time.

High resolution imaging of wide fields has been a prerogative of space telescopes for decades. Multi-conjugate adaptive optics (MCAO) is a key technology for the future of ground-based astronomy, especially as we approach the era of ELTs, where the large apertures will provide diffraction limits that will significantly surpass even the James Webb Space Telescope. NFIRAOS will be the first light MCAO system for the Thirty Meter Telescope and to support its development I have worked on HeNOS, its test bench integrated in Victoria at NRC Herzberg. I have aligned the optics, tested the electronic hardware, calibrated the subsystems (cameras, deformable mirrors, light sources, etc.) and characterized the system parameters. Development and support for future MCAO instruments also involves data analysis, a critical process in delivering the expected performance of any scientific instrument. To develop a strategy for optimal stellar photometry with MCAO, I have observed the Galactic globular cluster NGC 1851 with GeMS, the MCAO system on the 8-meter Gemini South telescope. From near-infrared images of this target in two bands, I have found the optimal parameters to employ in the profile-fitting photometry and calibration. As testimony to the precision of the results, I have obtained the deepest near-infrared photometry of a crowded field from the ground and used it to determine the age of the cluster with a method recently proposed that exploits the bend in the lower main sequence. The precise color-magnitude diagram also allows us to clearly observe the double subgiant branch for the first time from the ground, caused by the multiple stellar populations in the cluster. As the only facility MCAO system, GeMS is an important instrument that serves to illuminate the challenges of obtaining accurate photometry using such a system. By coupling the knowledge acquired from an instrument already on-sky with experiments in the lab on a prototype of a future system, I have addressed new challenges in photometry and astrometry, like the promising technique of point spread function reconstruction. This thesis informs the development of appropriate data processing techniques and observing strategies to ensure the ELTs deliver their full scientific promise over extended fields of view. / Graduate

We report photometric measurements of a sodium resonance guide star against the daylight sky when observed through a tuned magneto-optical filter (MOF). The MOF comprises a sodium vapor cell in a kilogauss-level magnetic field between crossed polarizers and has a very narrow transmission profile at the sodium D-2 resonance of approximately 0.008 nm. Our observations were made with the 1.5 m Kuiper telescope on Mt. Bigelow, AZ, which has a separately mounted guide star laser projecting a circularly polarized single-frequency beam of approximately 6.5 W at 589.16 nm. Both the beam projector and the 1.5 m telescope were pointed close to zenith; the baseline between them is approximately 5 m. Measurements of the guide star were made on the morning of 2016 March 24 using an imaging camera focused on the beacon and looking through the full aperture of the telescope. The guide star flux was estimated at 1.20x10(6) photon/m(2)/s while at approximately 45 minutes after sunrise, the sky background through the MOF was 1100 photon/m(2)/s/arcsec(2). We interpret our results in terms of thermal infrared observations with adaptive optics on the next generation of extremely large telescopes now being built.

The recent advent of next generation ground-based telescopes, code-named Extremely Large Telescopes (ELT), highlights the beginning of a forced march toward an era of deploying instruments capable of exploiting starlight captured by mirrors at an unprecedented scale. This confronts the astronomy community with both a daunting challenge and a unique opportunity. The challenge arises from the mismatch between the complexity of current instruments and their expected scaling with the square of the future telescope diameters, on which astronomy applications have relied to produce better science. To deliver on the promise of tomorrow’s ELT, astronomers must design new technologies that can effectively enhance the performance of the instrument at scale, while compensating for the atmospheric turbulence in real-time. This is an unsolved problem. This problem presents an opportunity because the astronomy community is now compelled to rethink essential components of the optical systems and their traditional hardware/software ecosystems in order to achieve high optical performance with a near real-time computational response. In order to realize the full potential of such instruments, we investigate a technique supporting Adaptive Optics (AO), i.e., a dedicated concept relying on turbulence tomography. In particular, a critical part of AO systems is the supervisor module, which is responsible for providing the system with a Tomographic Reconstructor (ToR) at a regular pace, as the atmospheric turbulence evolves over an observation window. In this thesis, we implement an optimized supervisor module and assess it under real configurations of the future European ELT (E-ELT) with a 39m diameter, the largest and most complex optical telescope ever conceived. This necessitates manipulating large matrix sizes (i.e., up to 100k × 100k) that contain measurements captured by multiple wavefront sensors. To address the complexity bottleneck, we employ high performance computing software solutions based on cutting-edge numerical algorithms using asynchronous, fine-grained computations as well as approximations techniques that leverage the resulting matrix data structure. Furthermore, GPU-based hardware accelerators are used in conjunction with the software solutions to ensure reasonable time-to-solution to cope with rapidly evolving atmospheric turbulence. The proposed software/hardware solution permits to reconstruct an image with high accuracy. We demonstrate the validity of the AO systems with a third-party testbed simulating at the E-ELT scale, which is intended to pave the way for a first prototype installed on-site

The aim of this master thesis is primarily to develop a methodological framework for a contracting authority receiving an abnormally low bid. The theoretical part of the thesis outlines the basic terms and definitions, analyzes a public tender from the perspective of a contracting authority and defines an extremely low bid price. The practical part of the thesis applies the methodological framework for dealing with an extremely low bid price on the case study, where on the set of selected areas of mechanical items indicates possible views above the limit costs of individual items costing unit prices of construction work.