Coastal road asset management: Dealing with uncertainty using quantitative erosion monitoring and modelling

The A183 is an essential transportation link in the northeast UK that joins coastal areas from South Shields to Sunderland. The route runs through the hinterland of Marsden Bay and concerns have been raised about the proximity of the road to the eroding cliff line. The Shoreline Management Plan (Lane and Guthrie, 2007) sets out the overarching management policy in the area and, based on the analyses of historic map data, uses projected coastal cliff retreat rates of 0.1 – 0.2 m a-1, although more recent investigations have suggested the rates may be nearer 0.04 – 0.1 m a-1. Quantitative data on the true rates and nature of cliff erosion are scarce and asset management decisions typically use the higher rate of 0.2 m a-1 when considering the potential impact on road operations and lifespan in order to account for uncertainty and future sea-level rise; which is additionally used to accelerate the predicted rates of retreat. Consequently, an enhanced high order estimate of cliff erosion rates has restricted the serviceability of the A183 to within 20 – 50 years, and there are three areas (pinch points) of particular concern where the close proximity of the cliff line threatens the safe operation of the road. This approach and the data it uses suggest that significant and potentially costly decisions may soon be required to ensure the viability of this vital transport corridor. Set against the context of assumed high cliff erosion rates, and further predicted increases to this metric, this work presents the results of a re-evaluation of existing map and aerial imagery data that highlights the typically high uncertainty associated with historic map data. The errors often exceed the changes being detected in rock cliffs, producing contradictory results and variability in processing and interpretation that restricts the reliability of the data used in current policy decisions. Using a significance-based analysis, questions are raised about how appropriate it is to reduce a three-dimensional recession process down to a single linear retreat. To provide a more appropriate and accurate assessment of the erosion occurring here we present the results of a monitoring approach of the Marsden Bay site using three-dimensional survey analyses to improve understanding of cliff failures at the site and ultimately to aid policy decisions

Decoding Complex Erosion Responses for the Mitigation of Coastal Rockfall Hazards Using Repeat Terrestrial LiDAR

A key factor limiting our understanding of rock slope behavior and associated geohazards is the interaction between internal and external system controls on the nature, rates, and timing of rockfall activity. We use high-resolution, monthly terrestrial light detection and ranging (LiDAR) surveys over a 2 year monitoring period to quantify rockfall patterns across a 0.6 km-long (15.3 × 103 m2) section of a limestone rock cliff on the northeast coast of England, where uncertainty in rates of change threaten the effective planning and operational management of a key coastal cliff top road. Internal system controls, such as cliff material characteristics and foreshore geometry, dictate rockfall characteristics and background patterns of activity and demonstrate that layer-specific analyses of rockfall inventories and sequencing patterns are essential to better understand the timing and nature of rockfall risks. The influence of external environmental controls, notably storm activity, is also evaluated, and increased storminess corresponds to detectable rises in both total and mean rockfall volume and the volumetric contribution of large (>10 m3) rockfalls at the cliff top during these periods. Transient convergence of the cumulative magnitude–frequency power law scaling exponent (ɑ) during high magnitude events signals a uniform erosion response across the wider cliff system that applies to all lithologies. The tracking of rockfall distribution metrics from repeat terrestrial LiDAR in this way demonstrably improves the ability to identify, monitor, and forecast short-term variations in rockfall hazards, and, as such, provides a powerful new approach for mitigating the threats and impacts of coastal erosion

Moving Beyond CHO: Alternative host systems may be the future of biotherapeutics

CHO cells are the primary expression system for recombinant proteins with significant investment over the last three decades resulting in robust cell lines and processes. The flexible nature of CHO has lent itself to multiple process formats, such as fed batch, perfusion and continuous cultures, and advances in omics technology has enabled customization of media formulations and targeted engineering of CHO cells. This knowledge has led to large gains in protein productivity that can be captured with culture duration and/or scale. Despite this, constant pressure exists to reduce cost of manufacturing and improve per batch productivity to meet the needs of increased patient populations and increase accessibility of these therapeutics. Biogen has partnered with MIT to take a holistic view of the potential future of biomanufacturing to identify technologies that can make step changes in productivity and cost reduction. This effort has identified the host system as the most important factor to enabling this vision. Specifically, a non-mammalian host could be the key to realizing the most significant gains in productivity and reduction in cost of manufacturing. Through this initiative, we sought to take a more comprehensive approach to investigate alternative hosts for recombinant antibody production. Eight non-mammalian hosts were selected based on several properties, including proven secretion of recombinant protein products, ability to glycosylate proteins, established genome or molecular biology toolkit, amongst others. The final panel of organisms included yeast, filamentous fungi, a diatom, and a trypanosome. In collaboration with Amyris, we evaluated these eight non-mammalian host cell lines to compare their suitability as a potential primary host for the biotechnology industry. Only non-engineered, wild-type strains were used as a starting point for this evaluation, which assessed the ability of each host to express the same IgG1 model antibody. The outcome of this comparative analysis demonstrated that several of the alternative hosts could express full length antibody with acceptable glycoforms. Additionally, the ease of culture, ability to engineer the genome, and flexibility of carbon source were assessed. As an output of this work, the most productive strains will be made available for use without restrictions to allow others in the community to freely work with these hosts. Based on this initial assessment, a strategy to further investigate the potential of the most promising hosts will be shared

Beyond CHO – Non-mammalian hosts could be the future expression systems of choice for recombinant biotherapeutics

Over the last 30 years there have been tremendous advances in CHO cell culture process engineering. Novel process concepts, such as fed batch, perfusion and continuous cultures, evolved from a deep understand of CHO metabolic needs and extensive media/feed formulation development. This knowledge has led to large gains in protein productivity that can be captured with culture duration and/or scale. The biotechnology industry is consistently pressured to reduce cost of manufacturing and improve per batch productivity. Independent, but related to this burden, is the ability to support an ever growing patient population with high doses of therapeutic protein. As such, Biogen partnered with MIT to take a holistic view of the potential future of biomanufacturing to identify technologies that can make step changes in productivity and cost reduction. These efforts have cast doubt that CHO would be the optimal host in the future, whereas a non-mammalian host could be a key to realizing the most significant gains in productivity and reduction in cost of manufacturing. Recombinant antibody production from non-mammalian hosts has been reported in the past, for example from the yeast pichia and filamentous fungi Trichoderma, and antibody material produced from pichia has been used in clinical trials. In the next phase of this initiative, we sought to take a more comprehensive approach to investigate alternative hosts in recombinant antibody production. Eight non-mammalian hosts were selected based on a number of properties, including proven secretion of recombinant protein products, ability to glycosylate proteins, established genome or molecular biology toolkit, amongst other characteristics. We designed an experimental plan that would enable more straightforward comparative analysis between hosts and included two main criteria to maintain a level playing field. First, only non-engineered, wild-type strains would be used as a starting point for all eight hosts of interest. Second, a single IgG1 model antibody was selected to be expressed by all hosts. In this presentation, the outcome of this comparative analysis will be discussed, including productivity values and details of the model antibody product quality. Based on this data the most productive strains will be made available for use without restrictions to allow others in the community to freely work with these hosts

Sedimentological characterization of Antarctic moraines using UAVs and Structure-from-Motion photogrammetry

In glacial environments particle-size analysis of moraines provides insights into clast origin, transport history, depositional mechanism and processes of reworking. Traditional methods for grain-size classification are labour-intensive, physically intrusive and are limited to patch-scale (1m2) observation. We develop emerging, high-resolution ground- and unmanned aerial vehicle-based ‘Structure-from-Motion’ (UAV-SfM) photogrammetry to recover grain-size information across an moraine surface in the Heritage Range, Antarctica. SfM data products were benchmarked against equivalent datasets acquired using terrestrial laser scanning, and were found to be accurate to within 1.7 and 50mm for patch- and site-scale modelling, respectively. Grain-size distributions were obtained through digital grain classification, or ‘photo-sieving’, of patch-scale SfM orthoimagery. Photo-sieved distributions were accurate to <2mm compared to control distributions derived from dry sieving. A relationship between patch-scale median grain size and the standard deviation of local surface elevations was applied to a site-scale UAV-SfM model to facilitate upscaling and the production of a spatially continuous map of the median grain size across a 0.3 km2 area of moraine. This highly automated workflow for site scale sedimentological characterization eliminates much of the subjectivity associated with traditional methods and forms a sound basis for subsequent glaciological process interpretation and analysis

Modelling outburst floods from moraine-dammed glacial lakes

In response to climatic change, the size and number of moraine-dammed supraglacial and proglacial lake systems have increased dramatically in recent decades. Given an appropriate trigger, the natural moraine dams that impound these proglacial lakes are breached, producing catastrophic Glacial Lake Outburst Floods (GLOFs). These floods are highly complex phenomena, with flood characteristics controlled, in the first instance, by the style of breach formation. Downstream, GLOFs typically exhibit transient, often non-Newtonian fluid dynamics as a result of high rates of sediment entrainment from the dam structure and channel boundaries. Combined, these characteristics introduce numerous modelling challenges. In this review, the historical, contemporary and emerging approaches available to model the individual stages, or components, of a GLOF event are introduced and discussed. A number of methods exist to model the stages of a GLOF event. Dam-breach models can be categorised as being empirical, analytical or numerical in nature, with each method having significant advantages and shortcomings. Empirical relationships that produce estimates of peak discharge and time to peak are straightforward to implement, but the applicability of these models is often limited by the nature of the case study data from which they are derived. Furthermore, empirical models neglect the inclusion of basic hydraulic principles that describe the mechanics of breach formation. Analytical or parametric models simulate breach development using simplified versions of the physically based equations that describe breach enlargement, whilst complex, physically-based codes represent the state-of-the-art in numerical dam-breach modelling. To date, few of the latter have been applied to investigate the moraine-dam failure problem. Despite significant advances in the physical complexity and availability of higher-order hydrodynamic solvers, the majority of published accounts that have attempted to reconstruct or predict GLOF characteristics have been limited, often by necessity, to the use of relatively simplistic models. This is in part attributable to the unavailability of terrain models of many high-mountain catchments at the fine spatial resolutions required for the effective application of numerically-sophisticated codes, and their proprietary (and often cost-prohibitive) nature. However, advanced models are experiencing increasing use in the glacial hazards literature. In particular, the suitability of emerging mesh-free, particle-based methods for simulating dam-breach and GLOF routing may represent a solution to many of the challenges associated with modelling this complex phenomenon. Sources of uncertainty in the GLOF modelling chain have been identified by various workers. However, to date their significance for the robustness of reconstructive and predictive modelling efforts have been largely unexplored and quantified in detail. These sources include the geometric and material characterisation of moraine dam complexes, including lake bathymetry and the presence and extent of buried ice, initial conditions (freeboard, precise spillway dimensions), spatial discretisation of the down-valley domain, hydrodynamic model dimensionality and the dynamic coupling of successive components in the GLOF model cascade

A qualitative exploration of oral health care among stroke survivors living in the community.

Background: Dental disease is highly prevalent in people with stroke. Stroke survivors regard oral hygiene as an important, yet neglected, area. The aim was to explore experiences of and barriers to oral care, particularly in relation to oral hygiene practice and dental attendance, among stroke survivors in the community. Methods: This was a qualitative study incorporating a critical realist approach. Interviews were conducted with community-dwelling stroke survivors requiring assistance with activities of daily living, and focus groups were held with health and care professionals. Interviews and focus groups were recorded and transcribed verbatim. Thematic analysis was conducted. Results: Twenty-three stroke survivors were interviewed, and 19 professionals took part in 3 focus groups. Professionals included nurses, speech and language therapists, occupational therapists, dieticians, professional carers and dental staff. Interviews revealed difficulties in carrying out oral hygiene self-care due to fatigue, forgetfulness and limb function and dexterity problems. Routine was considered important for oral hygiene self-care and was disrupted by hospitalization resulting from stroke. Professionals highlighted gaps in staff training and confidence in supporting patients with oral care. Access to dental services appeared particularly problematic for those who were not registered with a dentist pre-stroke. Conclusion: Oral hygiene routines may be disrupted by stroke, and resulting disabilities may make regular oral self-care more difficult. This study has identified specific barriers to oral hygiene self-care and dental service access. Findings from this study are feeding into the development of an intervention to support stroke survivors with oral care

Numerical modeling of glacial lake outburst floods using physically based dam-breach models

The instability of moraine-dammed proglacial lakes creates the potential for catastrophic glacial lake outburst floods (GLOFs) in high-mountain regions. In this research, we use a unique combination of numerical dam-breach and two-dimensional hydrodynamic modelling, employed within a generalised likelihood uncertainty estimation (GLUE) framework, to quantify predictive uncertainty in model outputs associated with a reconstruction of the Dig Tsho failure in Nepal. Monte Carlo analysis was used to sample the model parameter space, and morphological descriptors of the moraine breach were used to evaluate model performance. Multiple breach scenarios were produced by differing parameter ensembles associated with a range of breach initiation mechanisms, including overtopping waves and mechanical failure of the dam face. The material roughness coefficient was found to exert a dominant influence over model performance. The downstream routing of scenario-specific breach hydrographs revealed significant differences in the timing and extent of inundation. A GLUE-based methodology for constructing probabilistic maps of inundation extent, flow depth, and hazard is presented and provides a useful tool for communicating uncertainty in GLOF hazard assessment

Blue-ice moraines formation in the Heritage Range, West Antarctica: implications for ice sheet history and climate reconstruction

Blue ice is found in areas of Antarctica where katabatic winds, focussed by steep surface slopes or by topography around nunataks, cause enhanced surface ablation. This process draws up deeper, older ice to the ice sheet surface, often bringing with it englacial sediment. Prevailing theories for dynamically stable moraine surfaces in East Antarctica suggest that: (i) it is this material, once concentrated, that forms blue-ice moraines (BIM), (ii) that the moraine formation can be dated using cosmogenic isotope approaches, and that, (iii) since we expect an increase in exposure age moving away from the ice margin towards bedrock, dating across the moraine can be used to constrain ice-sheet history. To test this lateral accretion model for BIM formation we visited Patriot, Marble and Independence Hills in the southern Heritage Range, West Antarctica. Detailed field surveys of surface form, sediment and moraine dynamics were combined with geophysical surveys of the englacial structure of the moraines and cosmogenic nuclide analysis of surface clasts. Results suggest sediment is supplied mainly by basal entrainment, supplemented by debris-covered valley glaciers transferring material onto the ice sheet surface, direct deposition from rock-fall and slope processes from nunataks. We find that once sediment coalesces in BIM, significant reworking occurs through differential ablation, slope and periglacial processes. We bring these processes together in a conceptual model, concluding that many BIM in West Antarctica are dynamic and, whilst they persist through glacial cycles, they do not always neatly record ice sheet retreat patterns since linear distance from the ice margin does not always relate to increased clast exposure age. Understanding the dynamic processes involved in moraine formation is critical to the effective interpretation of the typically large scatter of cosmogenic nuclide exposure ages, opening a deep window into the million-year history of the West Antarctic Ice Sheet