Wear observations applied to Lifeboat Slipway Launches

It is necessary to use an inclined slipway to launch a large lifeboat in locations where there is no natural harbour or where there is a large tidal range. Slipway stations consist of an initial section where the boat is held on rollers followed by an inclined keelway of nickel/chromium coated steel, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. The lifeboat is subsequently recovered to the top of the slipway using a winch line. With the introduction of the new, larger Tamar class lifeboat existing boathouses are being upgraded and existing low friction coated steel slipway lining materials replaced with a low-friction jute fibre/phenolic resin composite, which is designed to operate with unlubricated conditions. This has led to problems of high wear on slipway panels, particularly where the lifeboat mounts the slipway for recovery. This paper describes a method for assessing slipway lining materials and lubricants. The selection of an appropriate test machine, the TE92 rotary tribometer, and design of a modified ring on disc arrangement incorporating panel interfaces and attaching holes effects is described. An experimental methodology is developed using programmed running intervals to simulate dwell effects. Experimental data is thus presented to establish slipway panel wear rates for a range of lubricants and contact pressures. Experimental results are incorporated into real-world slipway surveys to develop the wear scenario. Results and implications of this research for future lifeboat slipway design are discussed

The Behavioral Response of Harbor Seals to Seasonal Prey Pulses of Spawning Pacific Herring

The Pacific harbor seal (Phoca vitulina) is a noteworthy omission from the list of predators that aggregate at herring spawning sites, despite strong suggestive evidence that they are likely to respond to herring pulses. Working with the hypothesis that spawning herring aggregations are seasonally important prey for harbor seals, we tested several predictions using an analysis of harbor seal prey remains, GPS telemetry, and satellite-linked time/depth recorder data. Contrary to predictions, herring in harbor seal diet was comprised of 77% juveniles and 23% adults in the spawn season, versus 33% juveniles and 67% adults in the post-spawn season. Seal diving focus peaked at night during the post-spawn season, and seals exhibited less diving effort during the spawn season. Harbor seals did not however appear to alter their foraging behaviors to take advantage of spawning herring aggregations. The lack of response by harbor seals to spawning herring pulses is likely explained by seasonal differences in adult herring profitability, the availability of alternative prey, or a decline in local herring biomass

Wear and Friction Modeling on Lifeboat Launch Systems

The RNLI provides search and rescue cover along the UK and RoI coast using a variety of lifeboats and launch techniques. In locations where there is no natural harbour it is necessary to use a slipway to launch the lifeboat into the sea. Lifeboat slipway stations consist of an initial section where the boat is held on rollers followed by an inclined keelway lined with low friction composite materials, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. The lifeboat is later recovered using a winch line. It is common to manually apply grease to the composite slipway lining before each launch and recovery in order to ensure sufficiently low friction for successful operation. With the introduction of the Tamar class lifeboat it is necessary to upgrade existing boathouses and standardise slipway operational procedures to ensure consistent operation. The higher contact pressures associated with the new lifeboat have led to issues of high friction and wear on the composite slipway linings and the manual application of grease to reduce friction is to be restricted due to environmental impact and cost factors. This paper presents a multidisciplinary approach to modelling slipway panel wear and friction using tribometer testing in conjunction with finite element analysis and slipway condition surveys to incorporate common real-world effects such as panel misalignments. Finally, it is shown that a freshwater lubrication system is effective, reducing cost and environmental impacts while maintaining good friction and wear performance

Experimental Wear Modelling of Lifeboat Slipway Launches

It is necessary to use an inclined slipway to launch lifeboats in locations where there is no natural harbour. Slipway stations consist of an initial roller section followed by an inclined keelway, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. Contact is between the lifeboat keel and a lined, greased keelway and this that determines the friction along the slipway. This paper describes a bench test methodology to investigate this contact. The selection of a modified TE57 reciprocating tribometer and design of a modified pin on plate arrangement is discussed. A test schedule for both the original nickel/chromium coated steel lining and the new low-friction jute fibre/phenolic resin composite lining is developed to accurately reflect real world conditions including environmental contamination such as seawater or wind-blown sand. Environmentally conscious lubricants including water and bio-greases are investigated and compared for their effects in reducing slipway panel friction and wear. Experimental data is collected to establish wear mechanisms, wear volumes and friction characteristics for a range of lubricants and environmental contaminants for the two most common lifeboat keelway lining materials. Implications of this research for future lifeboat slipway design are discussed

Posterior Hox gene reduction in an arthropod: Ultrabithorax and Abdominal-B are expressed in a single segment in the mite Archegozetes longisetosus.

BACKGROUND: Hox genes encode transcription factors that have an ancestral role in all bilaterian animals in specifying regions along the antero-posterior axis. In arthropods (insects, crustaceans, myriapods and chelicerates), Hox genes function to specify segmental identity, and changes in Hox gene expression domains in different segments have been causal to the evolution of novel arthropod morphologies. Despite this, the roles of Hox genes in arthropods that have secondarily lost or reduced their segmental composition have been relatively unexplored. Recent data suggest that acariform mites have a reduced segmental component of their posterior body tagma, the opisthosoma, in that only two segments are patterned during embryogenesis. This is in contrast to the observation that in many extinct and extant chelicerates (that is, horseshoe crabs, scorpions, spiders and harvestmen) the opisthosoma is comprised of ten or more segments. To explore the role of Hox genes in this reduced body region, we followed the expression of the posterior-patterning Hox genes Ultrabithorax (Ubx) and Abdominal-B (Abd-B), as well as the segment polarity genes patched (ptc) and engrailed (en), in the oribatid mite Archegozetes longisetosus. RESULTS: We find that the expression patterns of ptc are in agreement with previous reports of a reduced mite opisthosoma. In comparison to the ptc and en expression patterns, we find that Ubx and Abd-B are expressed in a single segment in A. longisetosus, the second opisthosomal segment. Abd-B is initially expressed more posteriorly than Ubx, that is, into the unsegmented telson; however, this domain clears in subsequent stages where it remains in the second opisthosomal segment. CONCLUSIONS: Our findings suggest that Ubx and Abd-B are expressed in a single segment in the opisthosoma. This is a novel observation, in that these genes are expressed in several segments in all studied arthropods. These data imply that a reduction in opisthosomal segmentation may be tied to a dramatically reduced Hox gene input in the opisthosoma

The podiatric surgery theatre environment in the UK; is it conducive to learning? A quantitative study using the surgical theatre educational environment measure (STEEM)

Abstract Background In 2015 the Health and Care Professions Council (HCPC) reported that annotation of the register for podiatric surgery would improve the way in which risks are currently managed. The academic institutions provide the teaching environment for the ‘learnt’ Diploma in principles of podiatric surgery however the podiatric surgery departments facilitate the production of the next generation of podiatric surgeons. This research aimed to identify the major elements that contribute to the educational environment, and find and utilise a valid assessment tool which could identify discrete areas to be targeted for improvement as well as being used for monitoring of the environment. Methods A quantitative study using the Surgical Theatre Educational Environment Measure (STEEM) via an online tool was utilised for podiatrists working within podiatric surgery, podiatric surgical trainees and podiatric surgeons working towards the Certificate of Completion of Podiatric Surgery Training (CCPST) with a view to assessing the educational environment within the podiatric surgical theatre in the UK. Results 16/33 responses with a response rate of 48.4% the overall STEEM mean score was 122/160. Four subscales included teaching and training, learning opportunities, atmosphere, and workload/supervision/support were measured. The overall mean score of 76.73% suggests the learning environment may be considered satisfactory; however, areas for potential improvement are identifiable. Results reveal strengths such as a non-discriminatory surgical theatre atmosphere on racial grounds. Conclusions Perception was of a very satisfactory ‘Atmosphere’ within the theatre environment and a very satisfactory ‘opportunity to assist’ within the podiatric surgery theatre environment. The STEEM has potential to be applied further as a quality assessment tool whose results could be used to demonstrate part of the HCPC standards

Retrograde False Channel Perfusion: A Complication of Cardiopulmonary Bypass during Repair of Dissecting Aneurysms

The current surgical treatment of dissecting thoracic aneurysms that originate above the aortic valve and dissect distally (Type I—De Bakey [3]) requires cardiopulmonary bypass for repair of the proximal intimal tear and obliteration of the false lumen [1, 2, 4, 5]. When the dissecting process extends toward the femoral arteries, cannulation of these vessels may result in perfusion of the false lumen. In addition, although a femoral cannula is inserted into the true lumen, perfusion of the false channel may occur through large reentry sites in the distal abdominal aorta or beyond the bifurcation. Retrograde arterial flow through the false lumen would jeopardize the blood flow to the central nervous system and to other vital organs. We have observed this complication in 2 patients with complete aortic dissection (Type I) during what appeared to be an otherwise adequate surgical procedure