31,455 research outputs found
Attitude sensor
A device for controlling the attitude of a spacecraft is described. The device consists of two light sensors on a spacecraft that are mounted beneath a baffle which divides the light from a light source such as the sun or a star. The divided light reflects off of two reflective surfaces onto the two light sensors. When the spacecraft assumes its normal attitude, the baffle divides the light source into two equal parts, causing the two light sensors to produce equal outputs. When the light is equally detected, the stabilizing system is disconnected. Deviations from the normal attitude cause unequal distribution of the light source and energize the stabilizing system
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Rurality, productivity and skills in the East Midlands: final report
This report sets out the findings of research into the relationship between rurality, skills and productivity in the East Midlands. The report has been prepared by the Enterprise Research and Development Unit (ERDU) at the University of Lincoln on behalf of the East Midlands Development Agency (emda)
The cost of systemic corticosteroid-induced morbidity in severe asthma : a health economic analysis
The study data-set was supported by the Respiratory Effectiveness Group through their academic partnership with Optimum Patient Care. Ciaran O'Neill was funded under a HRB Research Leader Award (RL/13/16).Peer reviewedPublisher PD
Reliability and effective thermal conductivity of three metallic-ceramic composite insulating coatings on cooled hydrogen-oxygen rockets
An experimental investigation of the structural integrity and effective thermal conductivity of three metallic-ceramic composite coatings was conducted. These coatings were plasma sprayed onto the combustion side of water-cooled, 12.7-centimeter throat diameter, hydrogen-oxygen rocket thrust chambers operating at 2.07 to 4.14 meganewtons per square meter chamber pressure. The metallic-ceramic composites functioned for six to 17 cycles and for as long as 213 seconds of rocket operations and could have probably provided their insulating properties for many additional cycles. The effective thermal conductivity of all the coatings was in the range of 0.7472 to 4.483 w/(m)(K), which makes the coatings a very effective thermal barrier. Photomicrographic studies of cross-sectioned coolant tubes seem to indicate that the effective thermal conductivity of the coatings is controlled by contact resistance between the particles, as a result of the spraying process, and not the thermal conductivity of the bulk materials
Effective thermal conductivities of four metal ceramic composite coatings in hydrogen-oxygen rocket firings
An experimental investigation was conducted to determine the effective conductivities of four plasma-arc-sprayed, metal-ceramic gradated coatings on hydrogen-oxygen thrust chambers. The effective thermal conductivities were not a function of pressure or oxidant-to-fuel ratio. The various materials that made up these composites do not seem to affect the thermal conductivity values as much as the differences in the thermal conductivities of the parent materials would lead one to expect. Contact resistance evolving from the spraying process seems to be the controlling factor. The thermal conductivities of all the composites tested fell in the range of 0.75 to 7.5 watts per meter kelvin
Burden of podoconiosis in poor rural communities in Guliso woreda, western Ethiopia
Background. Podoconiosis is an environmental lymphoedema affecting people living and working barefoot on irritant red clay soil. Podoconiosis is relatively well described in southern Ethiopia, but remains neglected in other parts of the Ethiopian highlands. This study aimed to assess the burden of podoconiosis in rural communities in western Ethiopia.
Methodology/Principal Findings. A cross-sectional study was conducted in Gulliso woreda (district), west Ethiopia. A household survey in the 26 rural kebeles (villages) of this district was conducted to identify podoconiosis patients and to measure disease prevalence. A more detailed study was done in six randomly selected kebeles to describe clinical features of the disease, patients’ experiences of foot hygiene, and shoe wearing practice. 1,935 cases of podoconiosis were registered, giving a prevalence of 2.8%. The prevalence was higher in those aged 15 – 64 years (5.2%) and in females than males (prevalence ratio 2.6:1). 90.3% of patients were in the 15 – 64 year age group. In the detailed study, 335 cases were interviewed and their feet assessed. The majority of patients were farmers, uneducated, and poor. Two-third of patients developed the disease before the age of thirty. Almost all patients (97.0%) had experienced adenolymphangitis (ALA - red, hot legs, swollen and painful groin) at least once during the previous year. Patients experienced an average of 5.5 ALA episodes annually, each of average 4.4 days, thus 24 working days were lost annually. The incidence of ALA in podoconiosis patients was higher than that reported for filariasis in other countries. Shoe wearing was limited mainly due to financial problems.
Conclusions. We have documented high podoconiosis prevalence, frequent adenolymphangitis and high disease-related morbidity in west Ethiopia. Interventions must be developed to prevent, treat and control podoconiosis, one of the core neglected tropical diseases in Ethiopia
Systematic peer reviewing versus a discussion forum for promoting online learner success: an evaluation of innovative learning design for postgraduate students
Designing distance learning to ensure student success is of high importance and there
are well-known aspects of distance online learning that encourage retention such as
regular tutor support, clear structure, student self-reflection and online discussion with
peers (Doig and Hogg, 2013). A module for a new Postgraduate Certificate in Learning
and Teaching in Higher Education at the University of London was recently designed
using these plus innovative pedagogic features to promote student success. The
design included alignment between the assessment criteria and weekly discussion
forum activities. An ipsative assessment criterion indicated to students that they must
demonstrate their development and progress with their learning throughout the module
to encourage consistent engagement. The design also included a peer review process
that was managed through the Virtual Learning Environment with student reviews that
were anonymised. To identify which aspects of the design promoted success, we
collected data analytics for 50 students and explored links between online discussion
forum participation, peer review activities and student marks. Contrary to popular
expectations, engagement with the discussion forum is not a very good predictor of
completion and success. By contrast, engagement in peer review, and especially
giving feedback to peers, is a good predictor of success. Furthermore, early drop out
from peer review links to incomplete submission of assessments. Thus, spending time
on task in the peer review links to high or moderate performance, although a few
exceptions indicate that different learners might use different tools for success. This
study suggests a number of avenues for tutor development in online learning to
encourage retention such as using peer review activities that are time bound and well
organised. Assessment could include criteria for developmental progress as well as
outcome
Artifacts at 4.5 and 8.0 um in Short Wavelength Spectra from the Infrared Space Observatory
Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts
at 4.5 and 8 um. These artifacts appear in spectra from a recent data release,
OLP 10.0, as spurious broad emission features in the spectra of stars earlier
than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of
standard stars to corresponding spectra from the SWS reveals that these
artifacts result from an underestimation of the strength of the CO and SiO
molecular bands in the spectra of sources used as calibrators by the SWS.
Although OLP 10.0 was intended to be the final data release, these findings
have led to an additional release addressing this issue, OLP 10.1, which
corrects the artifacts.Comment: 14 pages, AASTex, including 5 figures. Accepted by ApJ Letter
Spatial distribution of podoconiosis in relation to environmental factors in Ethiopia: a historical review
BACKGROUND
An up-to-date and reliable map of podoconiosis is needed to design geographically targeted and cost-effective intervention in Ethiopia. Identifying the ecological correlates of the distribution of podoconiosis is the first step for distribution and risk maps. The objective of this study was to investigate the spatial distribution and ecological correlates of podoconiosis using historical and contemporary survey data.
METHODS
Data on the observed prevalence of podoconiosis were abstracted from published and unpublished literature into a standardized database, according to strict inclusion and exclusion criteria. In total, 10 studies conducted between 1969 and 2012 were included, and data were available for 401,674 individuals older than 15 years of age from 229 locations. A range of high resolution environmental factors were investigated to determine their association with podoconiosis prevalence, using logistic regression.
RESULTS
The prevalence of podoconiosis in Ethiopia was estimated at 3.4% (95% CI 3.3%-3.4%) with marked regional variation. We identified significant associations between mean annual Land Surface Temperature (LST), mean annual precipitation, topography of the land and fine soil texture and high prevalence of podoconiosis. The derived maps indicate both widespread occurrence of podoconiosis and a marked variability in prevalence of podoconiosis, with prevalence typically highest at altitudes >1500 m above sea level (masl), with >1500 mm annual rainfall and mean annual LST of 19-21°C. No (or very little) podoconiosis occurred at altitudes 24°C.
CONCLUSION
Podoconiosis remains a public health problem in Ethiopia over considerable areas of the country, but exhibits marked geographical variation associated in part with key environmental factors. This is work in progress and the results presented here will be refined in future work
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