3,705 research outputs found
Does angiotensin-1 converting enzyme genotype influence motor or cognitive development after pre-term birth?
BACKGROUND: Raised activity of the renin-angiotensin system (RAS) may both amplify inflammatory and free radical responses and decrease tissue metabolic efficiency and thus enhance cerebral injury in the preterm infant. The angiotensin-converting enzyme (ACE) DD genotype is associated with raised ACE and RAS activity as well as potentially adverse stimuli such as inflammation. The DD genotype has been associated with neurological impairments in the elderly, and thus may be also associated with poorer motor or cognitive development amongst children born preterm prematurely. METHODS: The association of DD genotype with developmental progress amongst 176 Caucasian children born at less than 33 weeks gestation (median birthweight 1475 g, range 645–2480 g; gestation 30 weeks, range 22–32; 108 male) was examined at 2 and 5 1/2 years of age. Measured neuro-cognitive outcomes were cranial ultrasound abnormalities, cerebral palsy, disability, Griffiths Developmental Quotient [DQ] at 2 yrs, and General Cognitive Ability [British Ability Scales-11] and motor performance [ABC Movement], both performed at 5 1/2 yrs. All outcomes were correlated with ACE genotype. RESULTS: The DD genotype was not associated with lower developmental quotients even after accounting for important social variables. CONCLUSION: These data do not support either a role for ACE in the development of cognitive or motor function in surviving infants born preterm or inhibition of ACE as a neuroprotective therapy
Development Studies Working Paper, no. 7
This paper reports on an investigation of the effects of the policy of Coloured Labour Preference in a rural area of the Western Cape. This policy, which has been analysed more fully elsewhere1, aims to restrict the number of black employees in the Western Cape, the region within which the policy is applied, by granting Coloureds preferential access to urban and rural labour markets. The Langkloof is a valley in which modern mechanised agricultural techniques are employed to specialise in the production of deciduous fruit, apples in particular. Farms are owned by whites, and the majority of farm workers are (classified) Coloured. A substantial number of black farm workers are also employed. The Kloof is served by two good roads and a narrow gauge railway linking the villages of the Kloof to Port Elizabeth. The Langkloof, moreover, is situated close to the boundary of the Western Cape, and therefore close to the line demarcating the region within which the policy of Coloured Labour Preference is applied. The investigation, which was executed in late 1980, included a number of visits to the Langkloof, interviews with officials of the Departments of Agriculture and Manpower, and of the Eastern Cape Administration Board, as well as a survey of white farmers' attitudes and practices. This survey was designed to elicit information relevant to the rural labour situation in the Langkloof, and to identify differences in attitudes and practices with regard to Coloured and black farmworkers. The focus of the survey was on the eastern half of the valley, commonly known as the Middel- and Onder-Langkloof.Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER
Neighborhoods of trees in circular orderings
In phylogenetics, a common strategy used to construct an evolutionary tree for a set of species X is to search in the space of all such trees for one that optimizes some given score function (such as the minimum evolution, parsimony or likelihood score). As this can be computationally intensive, it was recently proposed to restrict such searches to the set of all those trees that are compatible with some circular ordering of the set X. To inform the design of efficient algorithms to perform such searches, it is therefore of interest to find bounds for the number of trees compatible with a fixed ordering in the neighborhood of a tree that is determined by certain tree operations commonly used to search for trees: the nearest neighbor interchange (nni), the subtree prune and regraft (spr) and the tree bisection and reconnection (tbr) operations. We show that the size of such a neighborhood of a binary tree associated with the nni operation is independent of the tree’s topology, but that this is not the case for the spr and tbr operations. We also give tight upper and lower bounds for the size of the neighborhood of a binary tree for the spr and tbr operations and characterize those trees for which these bounds are attained
A Coarse Pointing Assembly for Optical Communication
In the framework of a contract with the European Space Agency, RUAG Space are developing a Coarse Pointing Assembly for an Optical Communication Terminal with the goal to enable high-bandwidth data exchange between GEO and/or LEO satellites as well as to earth-bound ground stations. This paper describes some development and testing aspects of such a high precision opto-mechanical device, with emphasis on the influence of requirements on the final design, the usage of a Bearing Active Preload System, some of the lessons learned on the BAPS implementation, the selection of a flex print design as rotary harness and some aspects of functional and environmental testing
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Application of Sentinel-2A data for pasture biomass monitoring using a physically based radiative transfer model
A large proportion of the global land surface is covered by pasture. The advent of the Sentinel satellites program provides free datasets with good spatiotemporal resolution that can be a valuable source of information for monitoring pasture resources. We combined optical remote sensing data (proximal hyperspectral and Sentinel 2A) with a radiative transfer model (PROSAIL) to estimate leaf area index (LAI), and biomass, in a dairy farming context. Three sites in Southern England were used: two pasture farms that differed in pasture type and management, and a set of small agronomy trial plots with different mixtures of grasses, legumes and herbs, as well as pure perennial ryegrass. The proximal and satellite spectral data were used to retrieve LAI via PROSAIL model inversion, which were compared against field observations of LAI. The potential of bands of Sentinel 2A that corresponded with a 10 m resolution was studied by convolving narrow spectral bands (from a handheld hyperspectral sensor) into Sentinel 2A bands (10 m). Retrieved LAI, using these spectrally resampled S2A data, compared well with measured LAI, for all sites, even for those with mixed species cover (although retrieved LAI was somewhat overestimated for pasture mixtures with high LAI). This proved the suitability of 10 m Sentinel 2A spectral bands for capturing LAI dynamics for different types of pastures. We also found that inclusion of 20 m bands in the inversion scheme did not lead to any further improvement in retrieved LAI. Sentinel 2A image based retrieval yielded good agreement with LAI measurements obtained for a typical perennial ryegrass based pasture farm. LAI retrieved in this way was used to create biomass maps (that correspond to indirect biomass measurements by Rising Plate Meter (RPM)), for mixed-species paddocks for a farm for which limited field data were available. These maps compared moderately well with farmer-collected RPM measurements for this farm. We propose that estimates of paddock-averaged and within-paddock variability of biomass are more reliably obtained from a combined Sentinel 2A-PROSAIL approach, rather than by manual RPM measurements. The physically based radiative transfer model inversion approach outperformed the Normalised Difference Vegetation Index based retrieval method, and does not require site specific calibrations of the inversion scheme
18F-FDG PET/MRI for staging and interim response assessment in pediatric and adolescent Hodgkin lymphoma: a prospective study with 18F-FDG PET/CT as reference standard
Rationale: Treatment regimens for pediatric Hodgkin's lymphoma (HL) depend on accurate staging and treatment response assessment, based on accurate disease distribution and metabolic activity depiction. With the aim of radiation dose reduction, we compared the diagnostic performance of 18F-FDG PET/MR to a 18F-FDG PET/CT reference standard for staging and response assessment. Methods: Twenty-four patients (mean age 15.4 years, range 8-19.5 years) with histologically proven HL were prospectively and consecutively recruited in 2015 and 2016, undergoing both 18F-FDG PET/CT and 18F-FDG PET/MRI at initial staging (N n = 24) and at response assessment (N n = 21). Diagnostic accuracy of 18F-FDG PET/MRI for both nodal and extra-nodal disease was compared to 18F-FDG PET/CT, which was considered as the reference standard. Discrepancies were retrospectively classified as perceptual or technical errors and 18F-FDG PET/MRI and 18F-FDG PET/CT were corrected by removing perceptual error. Agreement with Ann-Arbor staging and Deauville grading was also assessed. Results: For nodal and extranodal sites combined, corrected staging 18F-FDG PET/MRI sensitivity was 100% (95% confidence interval (CI) 96.7%-100%), specificity 99.5% (95%CI 98.3%-99.9%). Corrected response assessment 18F-FDG PET/MRI sensitivity was 83.3% (95%CI 36.5%-99.1%), specificity 100% (95%CI 99.2%-100%). Modified Ann-Arbor staging agreement between F18-FDG PET/CT and 18F-FDG PET/MRI was perfect (k = 1.0, P = 0.000). Deauville grading agreement between 18F-FDG PET/MRI and 18F-FDG PET/CT was excellent (k = 0.835, P = 0.000). Conclusion:18F-FDG PET/MRI is a promising alternative to 18F-FDG PET/CT for staging and response assessment in children with Hodgkin lymphoma
What’s sex got to do with it? A family-based investigation of growing up heterosexual during the twentieth century
This paper explores findings from a cross-generational study of the making of heterosexual relationships in East Yorkshire, which has interviewed women and men within extended families. Using a feminist perspective, it examines the relationship between heterosexuality and adulthood, focussing on sexual attraction, courtship, first kisses, first love and first sex, as mediated within family relationships, and at different historical moments. In this way, the contemporary experiences of young people growing up are compared and contrasted with those of mid-lifers and older adults who formed heterosexual relationships within the context of the changing social and sexual mores of the 1960s/1970s, and the upheavals of World War Two
SpineCreator: a Graphical User Interface for the Creation of Layered Neural Models.
There is a growing requirement in computational neuroscience for tools that permit collaborative model building, model sharing, combining existing models into a larger system (multi-scale model integration), and are able to simulate models using a variety of simulation engines and hardware platforms. Layered XML model specification formats solve many of these problems, however they are difficult to write and visualise without tools. Here we describe a new graphical software tool, SpineCreator, which facilitates the creation and visualisation of layered models of point spiking neurons or rate coded neurons without requiring the need for programming. We demonstrate the tool through the reproduction and visualisation of published models and show simulation results using code generation interfaced directly into SpineCreator. As a unique application for the graphical creation of neural networks, SpineCreator represents an important step forward for neuronal modelling
Engineering Assessment of the Miocene Aquifer System in Coastal Georgia
Proceedings of the 2001 Georgia Water Resources Conference, April 26 and 27, 2001, Athens, Georgia.Under contract to the Georgia Geologic Survey, Golder Associates Inc. (Golder) performed an
investigation to characterize the water-bearing
properties of the Miocene aquifer system in coastal
Georgia (also referred to as the upper and lower
Brunswick aquifers). The investigation focussed on
specific areas where a cap has been imposed restricting further withdrawals from the Upper Floridan Aquifer. At selected sites in Bryan, Chatham, Effingham and
Glynn counties, Golder installed pumping wells and
observation wells within the Miocene aquifer(s) and
performed 72-hour pumping tests. Results of the
investigation revealed that the lower Brunswick aquifer is absent at the sites in Chatham, Effingham and Bryan counties. Furthermore, the upper Brunswick aquifer at these locations is poorly developed, producing
sustainable yields of only five to 15 gpm. However,
there are Miocene wells within the Brunswick aquifer
in Bryan County that produce upwards of 100 gpm, indicating significant variation in the hydraulic
properties of the Miocene aquifer system in this area. Both the upper and lower Brunswick aquifers are present at the Glynn County site. While the upper
Brunswick aquifer at this location is capable of
producing only about 10 gpm, the lower Brunswick
aquifer can produce a sustainable yield of over 300 gpm. In addition to providing water resource
information to planners, developers and industry, the
data produced from this investigation will also be
incorporated into regional groundwater flow and transport models being developed by the USGS for
management of groundwater resources throughout
coastal Georgia.Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602-2202. The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia, the U.S. Geological Survey, the Georgia Water Research Institute as authorized by the Water Resources Research Act of 1990 (P.L. 101-397) or the other conference sponsors
Feedback control of surge irrigation systems
An automated irrigation control system is described which uses real-time feedback information
transmitted by infrared telemetry from runoff sensors to control intermittent or surge irrigation.
Flow runoff sensors monitor water depth in a measuring flume at the end of a field. Runoff
data are transmitted via an infrared transmitter and receiver to a portable microcomputer located
at the upper end of the field. Inflow data from a flow meter in the supply line are also fed to
the computer. Using the feedback data and field parameters provided by the operator, the
computer controls a surge valve for the advance phase of irrigation and determines cycle times
during the cutback or post-advance phase to limit runoff and total application depths to target
values set by the operator. All system components are battery-powered. Results from
preliminary field tests confirmed the ability of the system to control irrigation by real-time
feedback
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