Sonar behaviour in non-terrestrial ocean exploration

A goal for a future Europan payload is to determine the extent of the postulated sea, aspects of acoustic remote sensing are discussed with a view to operating a sonar in such an subsurface ocean

A wind tunnel investigation into the effects of roof curvature on the aerodynamic drag experienced by a light goods vehicle

Roof curvature is used to increase ground vehicle camber and enhance rear-body boat-tailing to reduce aerodynamic drag. Little aerodynamic data is published for light goods vehicles (LGVs) which account for a significant proportion of annual UK licensed vehicle miles. This paper details scale wind tunnel measurements at Re = 1.6 × 106 of a generic LGV utilising interchangeable roof panels to investigate the effects of curved roof profile on aerodynamic drag at simulated crosswinds between -6° and 16°. Optimum magnitudes of roof profile depth and axial location are suggested and the limited dataset indicates that increasing roof curvature is effective in reducing drag over a large yaw range, compared to a flat roof profile. This is primarily due to increased base pressure, possibly from enhanced mixing of longitudinal vortices shed from the rear-body upper side edges and increased turbulent mixing in the near-wake due to the increased effective boat-tail angle

Investigation of the aerodynamic characteristics of a lifting body in ground proximity

The use of cambered hull shapes in the next generation of lighter-than-air vehicles to enhance aerodynamic performance, together with optimized take-off manoeuvre profiles, will require a more detailed understanding of ground proximity effects for such aircraft. A series of sub-scale wind tunnel tests at Re = 1.4 x 106 on a 6:1 prolate spheroid are used to identify potential changes in aerodynamic lift, drag and pitching moment coefficients that are likely to be experienced on the vehicle hull in isolation when in close ground proximity. The experimental data is supported by a preliminary assessment of surface pressure changes using a high order panel method (PANAIR) and RANS CFD simulations to assess the flow structure. The effect of ground proximity, most evident when non-dimensional ground clearance (h/c) < 0.3, is to reduce lift coefficient, increase drag coefficient and increase the body pitching moment coefficient

Dags in Sheep Grazing Temperate Pastures: Causes and Consequences of Faecal Adhesion to Wool

Dags are the accumulation of faeces on wool in the perianal (breech) region of sheep and are a common problem in sheep fed good quality ryegrass based pastures in New Zealand. Their removal, or prevention, is costly but the consequences of doing nothing are severe. There is a high correlation between dags and flystrike (development of maggots) on sheep with dags, and dags reduce fleece value, live-weight gain and reproductive performance. Information summarised here suggests a range of factors contribute to the incidence of dags: lush (high quality) feeds, high voluntary feed intakes, presence of parasites in the gastro-intestinal tract, ingestion of parasite larvae, ingestion of fungal endophyte and a genetic predisposition to loose faeces. Faecal co elements, dry ground roughage, gums, detergent, serum, lanolin and water and measuring effects on adhesion. Other tests included measurement of faecal form, wool type and diet. Pelleted faeces did not adhere to wool, but interference with faecal form (e.g. mixing faeces) appeared to increase adhesion. It was concluded that faecal form was the most important factor affecting the incidence of dags and although conditions resulting in soft gooey faeces would facilitate their development, the chemical composition of faeces and of pasture were not the principal causes of dag formation. Factors associated with a high incidence of dags may increase the rate of digesta passage through the large intestine and/or alter intestinal function to affect faecal form and the adhesion of faeces to wool

Artefacts of authenticity

I recently made a visit to the Australian Museum in Sydney to study their archive of Aboriginal artefacts from western New South Wales, particularly boomerangs, clubs and shields. I say \u27artefacts\u27 because in this context this is how these objects were framed, not as art but as ethnographic objects. While I wanted to understand this archive better in terms of my own cultural heritage, my hope was to locate an object that might inspire my own seemingly flagging art practice. Moving slowly and thoughtfully from shelf to shelf, mindful of the museum attendant patiently supervising my visit, I was on the lookout for something that grabbed my immediate attention in terms of shape, materiality, and what might appear to be signs of cultural significance. From some preliminary research I had a vague sense of the range of objects that were considered unique to western New South Wales, so I quickly passed over objects that didn\u27t fit this impression

Why do firms hold so much cash? A tax-based explanation

U.S. corporations hold significant amounts of cash on their balance sheets, and these cash holdings have been justified in the existing empirical literature by transaction costs and precautionary motives. An additional explanation, considered in this study, is that U.S. multinational firms hold cash in their foreign subsidiaries because of the tax costs associated with repatriating foreign income. Consistent with this hypothesis, firms that face higher repatriation tax burdens hold higher levels of cash, hold this cash abroad, and hold this cash in affiliates that trigger high tax costs when repatriating earnings. Estimates indicate that a one standard deviation increase in the tax burden from repatriating foreign income is associated with a 7.9% increase in the ratio of cash to net assets. In addition, certain firms, specifically those that are less financially constrained domestically and those that are more technology intensive, exhibit a higher sensitivity of affiliate cash holdings to repatriation tax burdens.

Mesenchymal stem cells to augment therapeutic angiogenesis in hind-limb ischemia models: how important is their source?

Murine models of hind-limb ischemia are frequently used to assess interventions aimed at improving therapeutic angiogenesis in critical limb ischemia. Much of the current focus of angiogenesis lies with mesenchymal stem cells (MSCs). Important considerations when using these models include the strain of mouse, because some strains recover from ischemia more rapidly than others, and the MSC source. MSCs derived from certain strains generate increased levels of growth factors such as vascular endothelial growth factor. This may significantly affect the limb?s ability to generate collateral vessels