ANALYTICAL INVESTIGATION AND PREDICTION OF SPIN AND RECOVERY CHARACTERISTICS OF THE NORTH AMERICAN X-15 AIRPLANE

Spin and recovery characteristics of north american x-15 aircraf

High-temperature optically activated GaAs power switching for aircraft digital electronic control

Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas

Techniques to improve maneuver stability characteristics of a nonlinear wide-body transport airplane in cruise flight

The maneuver control stability characteristics of an aircraft are a flying qualities parameter of critical importance, to ensure structural protection as well as adequate predictability to the pilot. Currently, however, maneuver stability characteristics are not uniquely addressed in the Federal Aviation Regulations (FAR) Part 25, for transport aircraft. In past transport category certification programs, the Federal Aviation Administration (FAA) has used a combination of requirements (longitudinal control, vibration and buffeting, high-speed characteristics, and out-of-trim characteristics) to ensure safe and controllable maneuver stability characteristics over a range of flight conditions and airplane configurations. Controversies exist regarding each of these regulations, however, and considerable expenditures in terms of design studies and testing time have resulted from the requirements. It is also recognized that additional engineering guidance is needed for identifying acceptable nonlinear maneuver stability characteristics, particularly as they relate to relaxed stability, highly augmented transport configurations. The current trend in large aircraft design is toward relaxed, or even negative, static margins for improved fuel efficiency. The advanced flight control systems developed for these aircraft, in many instances, have rendered current aforementioned maneuver stability criteria either too stringent or of little practical use. Current design requirements do not account for these advanced designs. The objective was to evaluate a broad spectrum of linear and nonlinear longitudinal stability characteristics to generate data for defining satisfactory and unacceptable maneuver characteristics, as defined by pilot opinion. Primary emphasis was placed on two techniques of varying column force per normal acceleration. This study was a joint venture with four pilots participating; one from NASA, one from the FAA, and two from industry

Handling qualities of a wide-body transport airplane utilizing Pitch Active Control Systems (PACS) for relaxed static stability application

Piloted simulation studies have been conducted to evaluate the effectiveness of two pitch active control systems (PACS) on the flying qualities of a wide-body transport airplane when operating at negative static margins. These two pitch active control systems consisted of a simple 'near-term' PACS and a more complex 'advanced' PACS. Eight different flight conditions, representing the entire flight envelope, were evaluated with emphasis on the cruise flight conditions. These studies were made utilizing the Langley Visual/Motion Simulator (VMS) which has six degrees of freedom. The simulation tests indicated that (1) the flying qualities of the baseline aircraft (PACS off) for the cruise and other high-speed flight conditions were unacceptable at center-of-gravity positions aft of the neutral static stability point; (2) within the linear static stability flight envelope, the near-term PACS provided acceptable flying qualities for static stabilty margins to -3 percent; and (3) with the advanced PACS operative, the flying qualities were demonstrated to be good (satisfactory to very acceptable) for static stabilty margins to -20 percent

Electromagnetic Reduction of Plasma Density During Atmospheric Reentry and Hypersonic Flights

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76341/1/AIAA-32147-259.pd

Integrating an early childhood development programme into Bangladeshi primary health-care services: an open-label, cluster-randomised controlled trial

BACKGROUND: Poor development in young children in developing countries is a major problem. Child development experts are calling for interventions that aim to improve child development to be integrated into health services, but there are few robust evaluations of such programmes. Previous small Bangladeshi trials that used individual play sessions with mothers and their children (at home or in clinics), which were predominantly run by employed women, found moderate improvements on child development. We aimed to integrate an early childhood development programme into government clinics that provide primary health care and to evaluate the effects of this intervention on child cognition, language, and motor development, growth, and behaviour in a subsample of the children. METHODS: In this open-label cluster-randomised controlled trial, we recruited individuals from community clinics in Narsingdi district, Bangladesh. These clinics were randomly selected from a larger sample of eligible clinics, and they were assigned (1:1) to either deliver an intervention of 25 sessions, in which mothers of eligible children were shown how to support their child's development through play and interactions, or to deliver no intervention (control group). Participants were underweight children, defined as a weight-for-age Z score of -2 SDs of the WHO standard, who were aged 5-24 months and who lived near the clinic (defined as a walk of less than 30 min). Government health workers ran these sessions at the clinics as part of their routine work, and mothers and children attended fortnightly in pairs (instead of individual weekly home visits that were specified in the original programme). A subsample of children from each clinic was randomly selected for impact evaluation, and these children were assessed on the Bayley Scales of Infant and Toddler Development for their cognitive, language, and motor performance and for their behaviour with Wolke's ratings, before and after implementation of the intervention. The primary outcomes were the performance of this evaluation subsample on the Bayley and Wolke scales and their anthropometric measurements (weight, length or height, and head circumference) after 1 year of the intervention. This study is registered with ClinicalTrials.gov, number NCT02208531. FINDINGS: Between Nov 29, 2014, and April 30, 2015, 12 054 children in 90 clinics were screened, and between six and 25 underweight children were enrolled from each clinic. From the 2423 (20%) underweight children, we excluded 656 (27%) children who lived more than 30-min walking distance from the community clinics, and 30 (1%) children whose mothers did not consent to participate. We therefore enrolled 1737 (72%) children from these 90 clinics. After randomisation, the control group clinics included 878 (51%) children (who all received no intervention) and the intervention group clinics included 859 (49%) children (who all received the child development programme sessions). Eight children from each clinic (360 [41%] children from the control group clinics and 358 [42%] children from the intervention group clinics) were randomly selected for inclusion in the evaluation subsample. Between Feb 24, 2016, and Sept 7, 2016, 344 (96%) children in control group clinics and 343 (96%) children in intervention group clinics were assessed for the primary outcome. 16 (5%) children in the control group clinics and 15 (4%) children in the intervention group clinics did not provide all data and were not included in final analyses. An intention-to-treat analysis showed that the intervention significantly improved children's cognition (effect size 1·3 SDs, 95% CI 1·1 to 1·5; p=0·006), language (1·1 SDs, 0·9 to 1·2; p=0·01), and motor composite scores (1·2 SDs, 1·0 to 1·3; p=0·006) and behaviour ratings (ranging from 0·7 SDs, 0·5 to 0·9; p=0·02; to 1·1 SDs, 1·0 to 1·2; p=0·007), but the intervention had no significant effect on growth (p values ranged from 0·05 to 0·74). Three (1%) children in the intervention group died, but their deaths were not related to the intervention. INTERPRETATION: The extent and range of benefits of our intervention are encouraging. Health workers ran most of the sessions effectively and attendance was good, which is promising for scale-up of the intervention model. However, researchers trained and supervised the health workers, and the next step will be to determine whether the Bangladeshi ministry of health can perform these tasks. In future programmes, more attention needs to be paid to the nutrition of the children. FUNDING: Grand Challenges Canada (Saving Brains)

Financing Direct Democracy: Revisiting the Research on Campaign Spending and Citizen Initiatives

The conventional view in the direct democracy literature is that spending against a measure is more effective than spending in favor of a measure, but the empirical results underlying this conclusion have been questioned by recent research. We argue that the conventional finding is driven by the endogenous nature of campaign spending: initiative proponents spend more when their ballot measure is likely to fail. We address this endogeneity by using an instrumental variables approach to analyze a comprehensive dataset of ballot propositions in California from 1976 to 2004. We find that both support and opposition spending on citizen initiatives have strong, statistically significant, and countervailing effects. We confirm this finding by looking at time series data from early polling on a subset of these measures. Both analyses show that spending in favor of citizen initiatives substantially increases their chances of passage, just as opposition spending decreases this likelihood

Zinc intake, status and indices of cognitive function in adults and children: a systematic review and meta-analysis

In developing countries, deficiencies of micronutrients are thought to have a major impact on child development; however, a consensus on the specific relationship between dietary zinc intake and cognitive function remains elusive. The aim of this systematic review was to examine the relationship between zinc intake, status and indices of cognitive function in children and adults. A systematic literature search was conducted using EMBASE, MEDLINE and Cochrane Library databases from inception to March 2014. Included studies were those that supplied zinc as supplements or measured dietary zinc intake. A meta-analysis of the extracted data was performed where sufficient data were available. Of all of the potentially relevant papers, 18 studies met the inclusion criteria, 12 of which were randomised controlled trials (RCTs; 11 in children and 1 in adults) and 6 were observational studies (2 in children and 4 in adults). Nine of the 18 studies reported a positive association between zinc intake or status with one or more measure of cognitive function. Meta-analysis of data from the adult’s studies was not possible because of limited number of studies. A meta-analysis of data from the six RCTs conducted in children revealed that there was no significant overall effect of zinc intake on any indices of cognitive function: intelligence, standard mean difference of <0.001 (95% confidence interval (CI) –0.12, 0.13) P=0.95; executive function, standard mean difference of 0.08 (95% CI, –0.06, 022) P=0.26; and motor skills standard mean difference of 0.11 (95% CI –0.17, 0.39) P=0.43. Heterogeneity in the study designs was a major limitation, hence only a small number (n=6) of studies could be included in the meta-analyses. Meta-analysis failed to show a significant effect of zinc supplementation on cognitive functioning in children though, taken as a whole, there were some small indicators of improvement on aspects of executive function and motor development following supplementation but high-quality RCTs are necessary to investigate this further

The exceptional value of intact forest ecosystems

As the terrestrial human footprint continues to expand, the amount of native forest that is free from significant damaging human activities is in precipitous decline. There is emerging evidence that the remaining intact forest supports an exceptional confluence of globally significant environmental values relative to degraded forests, including imperilled biodiversity, carbon sequestration and storage, water provision, indigenous culture and the maintenance of human health. Here we argue that maintaining and, where possible, restoring the integrity of dwindling intact forests is an urgent priority for current global efforts to halt the ongoing biodiversity crisis, slow rapid climate change and achieve sustainability goals. Retaining the integrity of intact forest ecosystems should be a central component of proactive global and national environmental strategies, alongside current efforts aimed at halting deforestation and promoting reforestation

Care during the third stage of labour: A postal survey of UK midwives and obstetricians

<p>Abstract</p> <p>Background</p> <p>There are two approaches to care during the third stage of labour: Active management includes three components: administration of a prophylactic uterotonic drug, cord clamping and controlled cord traction. For physiological care, intervention occurs only if there is clinical need. Evidence to guide care during the third stage is limited and there is variation in recommendations which may contribute to differences in practice. This paper describes current UK practice during the third stage of labour.</p> <p>Methods</p> <p>A postal survey of 2230 fellows and members of the Royal College of Obstetricians and Gynaecologists (RCOG) and 2400 members of the Royal College of Midwives was undertaken. Respondents were asked about care during the third stage of labour, for vaginal and caesarean births and their views on the need for more evidence to guide care in the third stage. The data were analysed in Excel and presented as descriptive statistics.</p> <p>Results</p> <p>1189 (53%) fellows and members of the RCOG and 1702 (71%) midwives responded, of whom 926 (78%) and 1297 (76%) respectively had conducted or supervised births in the last year. 93% (863/926) of obstetricians and 73% (942/1297) of midwives report 'always or usually' using active management. 66% (611/926) of obstetricians and 33% (430/1297) of midwives give the uterotonic drug with delivery of the anterior shoulder; this was intramuscular Syntometrine^®for 79% (728/926) and 86% (1118/1293) respectively. For term births, 74% (682/926) of obstetricians and 41% (526/1297) of midwives clamp the cord within 20 seconds, as do 57% (523/926) and 55% (707/1297) for preterm births. Controlled cord traction was used by 94% of both obstetricians and midwives. For caesarean births, intravenous oxytocin was the uterotonic used by 90% (837/926) of obstetricians; 79% (726/926) clamp the cord within 20 seconds for term births as do 63% (576/926) for preterm births.</p> <p>Physiological management was used 'always or usually' by 2% (21/926) of obstetricians and 9% (121/1297) of midwives. 81% (747/926) of obstetricians and 89% (1151/1297) of midwives thought more evidence from randomised trials was needed; the most popular question was when is best to clamp the cord.</p> <p>Conclusions</p> <p>Active management of the third stage of labour is widely used by both obstetricians and midwives in the UK. Syntometrine^®is usually used for vaginal births and oxytocin for caesarean births; when this is given and when the cord is clamped varies.</p