The host immune response to gastrointestinal nematode infection in sheep

non peer reviewedGastrointestinal nematode infection represents a major threat to the health, welfare and productivity of sheep populations worldwide. Infected lambs have a reduced ability to absorb nutrients from the gastrointestinal tract, resulting in morbidity and occasional mortality. The current chemo-dominant approach to nematode control is considered unsustainable due to the increasing incidence of anthelmintic resistance. In addition there is growing consumer demand for food products from animals not subjected to chemical treatment. Future mechanisms of nematode control must rely on alternative, sustainable strategies such as vaccination or selective breeding of resistant animals. Such strategies take advantage of the host's natural immune response to nematodes. The ability to resist gastrointestinal nematode infection is considered to be dependent on the development of a protective acquired immune response; although the precise immune mechanisms involved in initiating this process remain to be fully elucidated. In this paper current knowledge on the innate and acquired host immune response to gastrointestinal nematode infection in sheep and the development of immunity is reviewed.We gratefully acknowledge funding support for the research in our laboratories from the Teagasc Walsh Fellowship Programme, the Allan and Grace Kay Overseas Scholarship and the EC-funded FP7 Programme. We also thank the BBSRC Animal Health Research Club for funding part of this research (grant BB/l004070/1

Prediction of temperature rise in low voltage high current electrical switchboards

At present, the electrical switchboard designer us ually constructs a full-scale prototype and tests it at rated current to ascertain its temperature rise performance, under simulated normal operating conditions. Temperatures are then reduced by application of one or several techniques including modification of the switchboard design. Steady-state temperature rise within an electrical switchboard is attained when t he Joule heat generated by electrical losses is exactly balanced by the heat l ost by cooling. The basic factors affecting this heat balance in electrical switchboards are r eviewed in this thesis . Also, the available empirical and computer based techniques which have been used to predict the temperature rise of electrical components such as cables, busbars, and circuit breakers as well as electrical switchboards containing these components, are discussed in detail. In view of the time and expense of development testing using techniques such as the above, this thesis introduces the concept of representing · the electrical switchboard heat transfer processes of radiation, convection, conduction, and natural ventilation by thermal equivalent resistances which are analogous to resistances in electric field theory. It is shown how thermal equivalent resistance circuits of individual switchboard components enable evaluation of their temperature rise and power loss performance The temperature rise experiments and the deve l opment of thermal equivalent resistance circuits for a 400 A moulded case circuit breaker and a 1600 A medi um voltage air circuit breaker , for a wide range of unenclosed and enc losed opera t ing conditions, are descr ibed and analysed . This thesis also presents the results of tests performed on a number of typical switchboard ventilators to quantify in real terms t heir ability to remove internally generated Joule heat from within electrical switchboards by natural ventilation. This analysis required the construction of a ventilator experimental test rig which is used to accurately simulate the actual operating conditions of a ventilator in nn electrical switchboard. The visualisation of the air flow patterns through these ventilators is also investigated. In line with the above described experiments, tests are performed on a full-scale electrical switchboard to determine its temperature rise and power loss performance for various ventilation configurations . From the measurement of the small differential pressure drops across the switchboard ventilators and internal components , the major obstructions to natura l ventilation and convection air flow within the switchboard are identified . To conduct these experiments on the switchboard, an automatic testing system was developed. This system, using a HP85 personal computer, digital multifunction meter, process datal ogger, pneumatic scanning box, digital micromanometer, and a special IEEE 488 input/output device, enables the automatic measurement, logging , and processing of electrical switch board experimental test data. This thesis also describes a computer program d e veloped by Van Leersum (16, 17) which has been used in the prediction of temperature rise o f simple non-vented heated enclos ures containing electronic equipment. A joint collaborative pro j ect between the Queensland University of Technology and the CSIRO's Division of Energy Technology was established to examine t he possibility of adapting this computer program, b a s~d upon the results of the t emperature rise tests on switchboard components d e scribed herein, so as to predict the t ~mperature r ise performance of vent i l ated enclosures such as electrica l switchboards. Simulations using this computer program are performed on both an idealised switchboard enclosure and a full-scale electrical switchboard over a wide range of operating conditions . Comparisons with experimental results revealed that the computer program could predict temperature rises to an accuracy of ±6 percent. It is concluded that although computer programs of this type are new to the electrical switchboard manufacturing industry in Australia and indeed throughout the world, their application in commercial switchboard design is justified in terms of both accuracy of temperature rise prediction and economic benefit development testing i n of that costly and time low voltage high current switchboards is not requi red. consuming electric