10 research outputs found

    Sea, sickness and cautionary tales: a multi-isotope study from a post-mediaeval hospital at the city-port of Gibraltar (AD 1462–1704)

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    Abstract: During the sixteenth to eighteenth centuries, Spanish ships sailed around the globe connecting Spain to its colonies. While documentary records offer rich details concerning life on board ship, archaeological information is essential to generating a full picture of the past. The cemetery at Old St Bernard’s Hospital, Gibraltar, provides an opportunity to study the skeletal remains of sailors. Following previous osteological research, carbon, nitrogen, oxygen and strontium isotope analyses were undertaken on thirty-three of these individuals. The results show that the, largely male, individuals had various different diets during life and came from several different places. Diets were largely based on C3 food chains; some individuals consumed C3 foods with low δ13C values; others consumed some marine foods, and a few individuals had a high trophic level diet, through the consumption of either freshwater resources or a high proportion of animal protein. The individuals spent their childhoods in several different places, although these homelands do not correlate simply with dietary variation. This variety in diets and homelands is consistent with our expectations for this hospital site given its location in a post-mediaeval entrepôt. The interpretation of these results are greatly helped by the available historical information and this has broader implications for the interpretation of isotope data elsewhere where the historical context of the site and the mobility patterns of the individuals are less well known

    A Numerical and Experimental Investigation of High-Speed Liquid Jets - Their Characteristics and Dynamics.

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    A comprehensive understanding of high-speed liquid jets is required for theirintroduction into engine and combustion applications. Their transient nature, shortlifetime, unique characteristics and the inability to take many experimental readings, has inhibited this need. This study investigates the outflow of a high-speed liquid jet into quiescent atmospheric air. The key characteristics present are, a bow shock wave preceding the jet head, an enhanced mixing layer and the transient deformation of the liquid jet core. The outflow regime is studied in an experimental and numerical manner.In the experimental investigation, a high-speed liquid water jet is generated using the momentum exchange by impact method. The jet velocity is supersonic with respect to the impinged gaseous medium. The resulting jet speed is Mach 1.8. The jet is visualised with the use of shadowgraph apparatus. Visualisation takes place over a variety of time steps in the liquid jet's life span and illustrates the four major development stages. The stages progress from initial rapid core jet expansion to jet stabilisation and characteristic uniform gradient formation. The visualisation shows that at all stages of the jet's life it is axi-symmetric. One dimensional nozzle analysis and a clean bow shock wave indicate that the pulsing jet phenomenon can be ignored.In the numerical investigation, a time marching finite volume scheme is employed. The bow shock wave characteristics are studied with the use of a blunt body analogy. The jet at a specific time frame is considered a solid body. The jet shape is found to have an important influence on the shock position and shape. Analysis of the results indicates a shock stand-off similar to that seen in experimental observations and the prediction of shock data.The jet life span is modelled using a species dependent density model. The transient calculations reproduce the key jet shape characteristics shown in experimental visualisation. The mushrooming effect and large mixing layer are shown to develop. These effects are strongest when the shock wave transience has yet to stabilise. Quantitative analysis of the mixing layer at varying time steps is presented

    Sea, sickness and cautionary tales: a multi-isotope study from a post-mediaeval hospital at the city-port of Gibraltar (AD 1462–1704)

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    During the sixteenth to eighteenth centuries, Spanish ships sailed around the globe connecting Spain to its colonies. While documentary records offer rich details concerning life on board ship, archaeological information is essential to generating a full picture of the past. The cemetery at Old St Bernard’s Hospital, Gibraltar, provides an opportunity to study the skeletal remains of sailors. Following previous osteological research, carbon, nitrogen, oxygen and strontium isotope analyses were undertaken on thirty-three of these individuals. The results show that the, largely male, individuals had various different diets during life and came from several different places. Diets were largely based on C3 food chains; some individuals consumed C3 foods with low δ13C values; others consumed some marine foods, and a few individuals had a high trophic level diet, through the consumption of either freshwater resources or a high proportion of animal protein. The individuals spent their childhoods in several different places, although these homelands do not correlate simply with dietary variation. This variety in diets and homelands is consistent with our expectations for this hospital site given its location in a post-mediaeval entrepôt. The interpretation of these results are greatly helped by the available historical information and this has broader implications for the interpretation of isotope data elsewhere where the historical context of the site and the mobility patterns of the individuals are less well known
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