39 research outputs found
Protocol for an automated, pragmatic, embedded, adaptive randomised controlled trial: behavioural economics-informed mobile phone-based reminder messages to improve clinic attendance in a Botswanan school-based vision screening programme.
BACKGROUND: Clinic non-attendance rates are high across the African continent. Emerging evidence suggests that phone-based reminder messages could make a small but important contribution to reducing non-attendance. We will use behavioural economics principles to develop an SMS and voice reminder message to improve attendance rates in a school-based eye screening programme in Botswana. METHODS: We will test a new theory-informed SMS and voice reminder message in a national school-based eye screening programme in Botswana. The control will be the standard SMS message used to remind parents/guardians to bring their child for ophthalmic assessment. All messages will be sent twice. The primary outcome is attendance for ophthalmic assessment. We will use an automated adaptive approach, starting with a 1:1 allocation ratio. DISCUSSION: As far as we are aware, only one other study has used behavioural economics to inform the development of reminder messages to be deployed in an African healthcare setting. Our study will use an adaptive trial design, embedded in a national screening programme. Our approach can be used to trial other forms of reminder message in the future. TRIAL REGISTRATION: ISRCTN 96528723 . Registered on 5 January 2022
Structure and origin of the J Anomaly Ridge, western North Atlantic Ocean
Author Posting. © American Geophysical Union, 1982. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 87, no. B11 (1982): 9389–9407, doi:10.1029/JB087iB11p09389.The J Anomaly Ridge is a structural ridge or step in oceanic basement that extends southwest from the eastern end of the Grand Banks. It lies beneath the J magnetic anomaly at the young end (M-4 to M-0) of the M series magnetic anomalies. Its structural counterpart beneath the J anomaly in the eastern Atlantic is the Madeira-Tore Rise, but this feature has been overprinted by post-middle Cretaceous deformation and volcanism. In order to study the origin and evolution of the J Anomaly Ridge-Madeira-Tore Rise system, we obtained seismic refraction and multichannel reflection profiles across the J Anomaly Ridge near 39°N latitude. The western ridge flank consists of a series of crustal blocks downdropped along west-dipping normal faults, but the eastern slope to younger crust is gentle and relatively unfaulted. The western flank also is subparallel to seafloor isochrons, becoming younger to the south. Anomalously smooth basement caps the ridge crest, and it locally exhibits internal, eastward-dipping reflectors similar in configuration to those within subaerially emplaced basalt flows on Iceland. When isostatically corrected for sediment load, the northern part of the J Anomaly Ridge has basement depths about 1400 m shallower than in our study area, and deep sea drilling has shown that the northern ridge was subaerially exposed during the middle Cretaceous. We suggest that most of the system originated under subaerial conditions at the time of late-stage rifting between the adjacent Grand Banks and Iberia. The excess magma required to form the ridge may have been vented from a mantle plume beneath the Grand Banks-Iberia rift zone and channelled southward beneath the rift axis of the abutting Mid-Atlantic Ridge. Resulting edifice-building volcanism constructed the ridge system between anomalies M-4 and M-0, moving southward along the ridge axis at about 50 mm/yr. About M-0 time, when true drift began between Iberia and the Grand Banks, this southward venting rapidly declined. The results were rapid return of the spreading axis to normal elevations, division of the ridge system into the separate J Anomaly Ridge and Madeira-Tore Rise, and unusually fast subsidence of at least parts of these ridges to depths that presently are near normal. This proposed origin and evolutionary sequence for the J Anomaly Ridge-Madeira-Tore Rise system closely matches events of uplift and unconformity development on the adjacent Grand Banks.This research was supported by the Office of Naval Research, contracts N00014-75-C-0210 and N00014-80-C-0098 to Lamont-Doherty Geological Observatory and contract N00014-79-C-0071 to Woods Hole Oceanographic Institution
Seismic velocities of granulites from the Seiland Petrographic Province (N. Norway): Implications for Scandinavian lower continental crust
Compressional and shear wave velocities have been measured in the laboratory at up to 1.0 GPa effective pressure on a suite of granulite facies rocks from the Seiland Petrographic Province. The suite may be of Precambrian age and the measurements were made to test a proposal that the suite represents lower continental crust. Compressional wave velocities at 0.4 GPa effective pressure range from 6.41–6.97 km s-1 with a mean of 6.71 km s-1 . Measurements of the parameter (∂V/∂Tp) suggest a value of a –0.8 x 10-3 km s-1 ºC-1 , and the temperature corrected mean velocity of about 6.5 km s-1 at 20 km depth is comparable to that found in parts of the lower crust in Scandinavia. The mean Poisson's ratio of 0.29 at 0.4 GPa is slightly higher than that found (0.276), but could be reduced if heterogeneity in the suite and the effect of higher pressures are taken into account. The occurrence of lower continental crust as a thrust slice in the Province is consistent with current ideas on the geological evolution of this area.
ARK: https://n2t.net/ark:/88439/y080958
Permalink: https://geophysicsjournal.com/article/260
 
Enhanced interpretation of magnetic survey data from archaeological sites using artificial neural networks
The use of magnetic surveys for archaeological prospecting is a well-established and versatile technique, and a wide range of data processing routines are often applied to further enhance acquired data or derive source parameters. Of particular interest in this respect is the application of artificial neural networks (ANNs) to predict source parameters such as the burial depths of detected features of interest. Within this study, ANNs based upon a multilayer perceptron architecture are used to perform the nonlinear mapping between buried wall features detected within the magnetic data and their corresponding burial depth for surveys in the ancient city of Butrint in southern Albania, achieving a greater level of information from the survey data.Suitable network training examples and test data were generated using forward models based upon ground-truth observations. The training procedure adopts a supervised learning routine that is optimized using a conjugate gradient method, while the learning algorithm also prunes network elements to prevent overregularization by reducing model complexity. Data processing was further enhanced by introducing rotational invariance using Zernike moments and by utilizing the combined output of a number, or committee, of networks. When applied to a section of survey data from Butrint, the ANN routine successfully predicted the burial depth of a number of detected wall features, with an rms error on the order of 0.20 m, and provided a coherent map of the buried building foundations. The neural network approach offered advantages in terms of efficiency and flexibility over more conventional data-inversion techniques within the context of the study, giving fast solutions for large, complex data sets while having high noise tolerance