Seismic structure of the continental margin of French Guiana: implications for the rifting and early spreading of the equatorial Atlantic

Recent studies of passive continental margins suggest that the rifting process produces a variety of structural styles. The along-strike continuity of these rifted margins is punctuated by significant lateral offsets, known as transform margins. Whilst many general features of both rift- and transform-style margins have been identified, the extent to which they are inter-related is not well understood. The equatorial Atlantic exhibits a high number of large offset mid-ocean ridge transform faults and associated fracture zones, which indicate the highly segmented nature of its margins. As such, this location provides an ideal setting for a study of the deep structure of both rift- and transform-style margin structures. This investigation forms part of the Amazon Cone Experiment, a large-scale geophysical study of the French Guiana and northeast Brazil margin in the west equatorial Atlantic. This study will provide evidence of crustal structure from recently acquired seismic, gravity and magnetic data, along two transects of the margin. The acquisition comprised 962 km of coincident multi-channel reflection and wide-angle refraction seismic data which were recorded by 20 ocean-bottom seismographs per transect, deployed at 10 km spacing. Ray-trace forward modelling of traveltime data from these instruments has resulted in two P-wave velocity-depth models of the subsurface structure which have been tested and further constrained by independent gravity free-air anomaly data. Interpretation of the resulting models suggests that the pre rift continental crust is 35- 37 km thick. While at the oceanward end or each transect oceanic crust is identified which, at 3.5-5.0 km thickness, is considered to be unusually thin. The manner in which this transition is accomplished is dramatically different between the two models. In the south of the survey area the crust thins abruptly by a factor of 6.4 over a distance of ~70 km, adjacent to a ~ 45 km ocean-continent transition zone. To the north, however, more gradual thinning over ~ 320 km associated with an abrupt transition to oceanic crust is observed. Neither profile shows evidence of the tilted fault blocks characteristic of rifted margins. There is no evidence for rift-related magmatism, commonly manifest as high P- wave velocity underplating or packages of seaward-dipping reflectors, along either profile. Hence, the margin is interpreted as non-volcanic, which suggests that rifting was not very rapid. On the basis of these results, a model of transtensional rifting is proposed, in which a component of motion oblique to the margin results in the production of relatively wide, leaky' transform margins. This model suggests that the French Guiana margin is segmented into rift- and transform-style structures. However, the transform margins exhibit unusually wide zones of continental crustal thinning as a result of the transtensional extension. For the Amazon Cone Experiment as a whole, anomalously thin oceanic crust is observed over a wide areal extent. This crust indicates that magma flow from the mantle is low and is interpreted to be a result of relatively cool asthenospheric mantle, slow spreading and the effect of large-scale fracture zones. The results of this study have implications for our understanding of the effects of transtensional stresses during rifting and mode of opening of the equatorial Atlantic

Optimising hospital designs and processes to improve efficiency and enhance the user experience

The health sector is facing increasing pressure to provide effective, efficient, and affordable care to the population it serves. The National Health Service (NHS) of the United Kingdom (UK) has regularly faced scrutiny with NHS England being issued a number of challenges in recent years to improve operational efficiency, reduce wasted space, and cut expenditure. The most recent challenge issued to NHS England has seen a requirement to save £5bn per annum by 2020, while reducing wasted space from 4.4% to 2.5% across the NHS estate. Similarly, satisfaction in the health service is also under scrutiny as staff retention and patient experiences are used in determining the performance of facilities. [Continues.

Building better healthcare – technologies to facilitate evidence-based design processes

Building better healthcare – technologies to facilitate evidence-based design processe

Crustal structure of the French Guiana margin, West Equatorial Atlantic

Geophysical data from the Amazon Cone Experiment are used to determine the structure and evolution of the French Guiana and Northeast Brazil continental margin, and to better understand the origin and development of along-margin segmentation. A 427-km-long combined multichannel reflection and wide-angle refraction seismic profile acquired across the southern French Guiana margin is interpreted, where plate reconstructions suggest a rift-type setting. The resulting model shows a crustal structure in which 35–37-km-thick pre-rift continental crust is thinned by a factor of 6.4 over a distance of ∼70 km associated with continental break-up and the initiation and establishment of seafloor spreading. The ocean–continent boundary is a transition zone up to 45 km in width, in which the two-layered oceanic-type crustal structure develops. Although relatively thin at 3.5–5.0 km, such thin oceanic crust appears characteristic of the margin as a whole. There is no evidence of rift-related magmatism, either as seaward-dipping sequences in the reflection data or as a high velocity region in the lower crust in the P-wave velocity model, and as a such the margin is identified as non-volcanic in type. However, there is also no evidence of the rotated fault block and graben structures characteristic of rifted margins. Consequently, the thin oceanic crust, the rapidity of continental crustal thinning and the absence of characteristic rift-related structures leads to the conclusion that the southern French Guiana margin has instead developed in an oblique rift setting, in which transform motion also played a significant role in the evolution of the resulting crustal structure and along-margin segmentation in structural style

Modeling and simulating hospital operations in a 3D environment

The use of dashboards to aid hospital decision makers in managerial and clinical decisions is well documented in the literature, though few broach the challenging subject of combining cost measurement with user satisfaction and building layout optimization. This paper presents an innovative dashboard in a 3D environment, providing decision makers with simulation capabilities using agent based simulation, allowing examination of their facility and the impact of policy, process and layout changes on patients and finances. An example is presented for an Emergency Department, wherein the presented dashboard revealed that the costs of constructing additional triage rooms would produce no benefit to patients; rather, a change in the process would be more beneficial compared with the existing situation. It is concluded that the developed dashboard allows users to make comparisons between multiple scenarios and visualize data in an intuitive format, allowing for decision makers to optimize their facility and operations

Maximising patient throughput using discrete-event simulation

As the National Health Service (NHS) of England continues to face tighter cost saving and utilisation government set targets, finding the optimum between costs, patient waiting times, utilisation of resources, and user satisfaction is increasingly challenging. Patient scheduling is a subject which has been extensively covered in the literature, with many previous studies offering solutions to optimise the patient schedule for a given metric. However, few analyse a large range of metrics pertinent to the NHS. The tool presented in this paper provides a discrete-event simulation tool for analysing a range of patient schedules across nine metrics, including: patient waiting, clinic room utilisation, waiting room utilisation, staff hub utilisation, clinician utilisation, patient facing time, clinic over-run, post-clinic waiting, and post-clinic patients still being examined. This allows clinic managers to analyse a number of scheduling solutions to find the optimum schedule for their department by comparing the metrics and selecting their preferred schedule. Also provided is an analysis of the impact of variations in appointment durations and their impact on how a simulation tool provides results. This analysis highlights the need for multiple simulation runs to reduce the impact of non-representative results from the final schedule analysis

Using evidence-based design to improve pharmacy department efficiency.

Using a case study of a pharmacy department rebuild in the South West of England, this article examines the use of evidence-based design to improve the efficiency and staff well-being with a new design. This article compares three designs, the current design, an anecdotal design, and an evidence-based design, to identify how evidence-based design can improve efficiency and staff well-being by reducing walking time and distance. Data were collected from the existing building and used to measure the efficiency of the department in its current state. These data were then mapped onto an anecdotal design, produced by architects from interviews and workshops with the end users, and an evidence-based design, produced by highlighting functions with high adjacencies. This changed the view on the working processes within the department, shifting away from a focus on the existing robotic dispensing system. Using evidence-based design was found to decrease the walking time and distance for staff by 24%, as opposed to the anecdotal design, which increased these parameters by 9%, and is predicted to save the department 248 min across 2 days in staff time spent walking

Maximising patient throughput using discrete-event simulation

As the National Health Service (NHS) of England continues to face tighter cost saving and utilisation government set targets, finding the optimum between costs, patient waiting times, utilisation of resources, and user satisfaction is increasingly challenging. Patient scheduling is a subject which has been extensively covered in the literature, with many previous studies offering solutions to optimise the patient schedule for a given metric. However, few analyse a large range of metrics pertinent to the NHS. The tool presented in this paper provides a discrete-event simulation tool for analysing a range of patient schedules across nine metrics, including: patient waiting, clinic room utilisation, waiting room utilisation, staff hub utilisation, clinician utilisation, patient facing time, clinic over-run, post-clinic waiting, and post-clinic patients still being examined. This allows clinic managers to analyse a number of scheduling solutions to find the optimum schedule for their department by comparing the metrics and selecting their preferred schedule. Also provided is an analysis of the impact of variations in appointment durations and their impact on how a simulation tool provides results. This analysis highlights the need for multiple simulation runs to reduce the impact of non-representative results from the final schedule analysis

A tool for signage placement recommendation in hospitals based on wayfinding metrics

Navigating a healthcare facility can prove challenging to both new and existing patients and visitors. Poor or ineffective use of signage within the facility may enhance navigational difficulties. Signage strategies within facility design tend to be produced without consideration of how people typically navigate a space. Thus, strategies that ‘work on paper’ may not, in reality, aid or optimize patient and visitor wayfinding. Existing strategies for determining signage placement may also prove costly in terms of time spent on manual analysis of a facility’s floor space, including the potential for overlooking prime signage locations when analysing large floor plans. This paper presents a tool which aims to aid signage placement strategies by analysing facility design and routes within it, based on natural wayfinding metrics found in existing literature. The tool is designed to enable quick analysis of large designs for analysing multiple routes, highlighting areas where signage placement would aid natural wayfinding. The outputs of the tool are presented as a colour map which overlays the original 3D model design, highlighting the key areas where signage may be appropriate. An example of how the tool can be utilised to aid effective sign strategy is demonstrated on a small healthcare facility design

Oceanic Residual Depth Measurements, the Plate Cooling Model and Global Dynamic Topography

Convective circulation of the mantle causes deflections of the Earth's surface that vary as a function of space and time. Accurate measurements of this dynamic topography are complicated by the need to isolate and remove other sources of elevation, arising from flexure and lithospheric isostasy. The complex architecture of continental lithosphere means that measurement of present-day dynamic topography is more straightforward in the oceanic realm. Here, we present an updated methodology for calculating oceanic residual bathymetry, which is a proxy for dynamic topography. Corrections are applied that account for the effects of sedimentary loading and compaction, for anomalous crustal thickness variations, for subsidence of oceanic lithosphere as a function of age, and for non-hydrostatic geoid height variations. Errors are formally propagated to estimate measurement uncertainties. We apply this methodology to a global database of 1,936 seismic surveys located on oceanic crust and generate 2,297 spot measurements of residual topography, including 1,161 with crustal corrections. The resultant anomalies have amplitudes of ±1 km and wavelengths of ∼1,000 km. Spectral analysis of our database using cross-validation demonstrates that spherical harmonics up to and including degree 30 (i.e. wavelengths down to 1,300 km) are required to accurately represent these observations. Truncation of the expansion at a lower maximum degree erroneously increases the amplitude of inferred long-wavelength dynamic topography. There is a strong correlation between our observations and free-air gravity anomalies, magmatism, ridge seismicity, vertical motions of adjacent rifted margins, and global tomographic models. We infer that shorter wavelength components of the observed pattern of dynamic topography may be attributable to the presence of thermal anomalies within the shallow asthenospheric mantle.This research is supported by a BP-Cambridge collaboration