Anaesthetic hazards of the 'passion gap' A case report

Dental abnormalities cause problems for both dentist and anaesthetist. The anaesthetic hazards associated with the 'passion gap' - a term used in the western Cape Province for removal of the top four incisor teeth, a practice widespread among members ot the Cape Coloured community - are discussed. Recommendations are made to assist the anaesthetist when dealing with such a patient

Behavioural tendencies of the last British–Irish Ice Sheet revealed by data–model comparison

Integrating ice-sheet models with empirical data pertaining to palaeo-ice sheets promotes advances in the models used in sea-level predictions and can improve our understanding of past ice-sheet behaviour. The large number of empirical constraints on the last British–Irish Ice Sheet make it ideal for model–data comparison experiments. Here, we present an ensemble of 600 model simulations, which are compared with data on former ice-flow extent, flow geometry and deglaciation timing. Simulations which poorly recreate data were ruled out, allowing us to examine the remaining physically realistic simulations which capture the ice sheets' behavioural tendencies. Our results led to a novel reconstruction of behaviour in the data-poor region of the North Sea, insights into the ice stream, potential ice-shelf and readvance dynamics, and the potential locations of peripheral ice caps. We also propose that the asynchronous behaviour of the British–Irish Ice Sheet is a consequence of the geography of the British Isles and the merging and splitting of different bodies of ice through saddle merger and collapse. Furthermore, persistent model–data mismatches highlight the need for model development, especially regarding the physics of ice–ocean interactions. Thus, this work highlights the power of integrating models and data, a long-held aim of palaeoglaciology

Recent progress on combining geomorphological and geochronological data with ice 1 sheet modelling, demonstrated using the last British-Irish Ice Sheet

Palaeo‐ice sheets are important analogues for understanding contemporary ice sheets, offering a record of ice sheet behaviour that spans millennia. There are two main approaches to reconstructing palaeo‐ice sheets. Empirical reconstructions use the available glacial geological and chronological evidence to estimate ice sheet extent and dynamics but lack direct consideration of ice physics. In contrast, numerically modelled simulations implement ice physics, but often lack direct quantitative comparison with empirical evidence. Despite being long identified as a fruitful scientific endeavour, few ice sheet reconstructions attempt to reconcile the empirical and model‐based approaches. To achieve this goal, model‐data comparison procedures are required. Here, we compare three numerically modelled simulations of the former British–Irish Ice Sheet with the following lines of evidence: (a) position and shape of former margin positions, recorded by moraines; (b) former ice‐flow direction and flow‐switching, recorded by flowsets of subglacial bedforms; and (c) the timing of ice‐free conditions, recorded by geochronological data. These model–data comparisons provide a useful framework for quantifying the degree of fit between numerical model simulations and empirical constraints. Such tools are vital for reconciling numerical modelling and empirical evidence, the combination of which will lead to more robust palaeo‐ice sheet reconstructions with greater explicative and ultimately predictive power

Fate tracing reveals the endothelial origin of hematopoietic stem cells

Hematopoietic stem cells (HSCs) originate within the aortic-gonado-mesonephros (AGM) region of the midgestation embryo, but the cell type responsible for their emergence is unknown since critical hematopoietic factors are expressed in both the AGM endothelium and its underlying mesenchyme. Here we employ a temporally restricted genetic tracing strategy to selectively label the endothelium, and separately its underlying mesenchyme, during AGM development. Lineage tracing endothelium, via an inducible VE-cadherin Cre line, reveals that the endothelium is capable of HSC emergence. The endothelial progeny migrate to the fetal liver, and later to the bone marrow, and are capable of expansion, self-renewal, and multilineage hematopoietic differentiation. HSC capacity is exclusively endothelial, as ex vivo analyses demonstrate lack of VE-cadherin Cre induction in circulating and fetal liver hematopoietic populations. Moreover, AGM mesenchyme, as selectively traced via a myocardin Cre line, is incapable of hematopoiesis. Our genetic tracing strategy therefore reveals an endothelial origin of HSCs