Thrust production and wake structure of a batoid-inspired oscillating fin.

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.

A simple method for fume cupboard performance assessment.

The performance of a fume cupboard is determined by a complex interaction of factors which are time consuming and expensive to determine. This paper describes a simple and practical means of ranking, and assessing fume cupboard installations that can help to discharge managerial responsibility for a 'safe' environment. The method also gives an economically viable and technically defensible system for assessing fume cupboard performance as part of upgrading exercises or performance audits. The assessment strategy uses flow visualisation techniques and measurements of inflow air velocity as well as overall condition evaluation to rank performance and identify poor performing cupboards. The method has been used to carry out a condition and performance survey of 199 fume cupboards, both aerodynamic and box-type designs, in an academic institution. The results of this survey are presented which not only highlight performance characteristics but also provide insights into user attitudes and knowledge of fume cupboard operation and performance. It is suggested that surveys such as this could be helpful in training programmes for laboratory workers to enable them to optimise the use of fume cupboards.

Computational fluid dynamics as a method for assessing fume cupboard performance.

A commercially available computational fluid dynamic (CFD) software program, specific for HVAC systems, was used to study the performance of an aerodynamic fume cupboard. The numerical results showed good qualitative agreement with physical measurements giving confidence in the CFD model to simulate and predict overall fume cupboard performance. However, there were some quantitative differences specifically around 'aerodynamic' features that could not be accurately simulated by the software code. The CFD model was clearly able to demonstrate differences in performance between good and bad cupboard designs, and show the importance of using rear baffles and lipfoils. It also showed the importance of good design features when a 'worker' was standing against the front edge or when there were draughts in front of the aperture. The computer model was used to simulate the gas tracer containment test method described in BS 7258 (1994) [Laboratory Fume Cupboards], and had a much greater sensitivity than the recommended physical measuring instruments. The results given in this paper demonstrate the potential for using a commercially available software package for the optimisation of fume cupboard design and testing. It also indicates the economy of using CFD compared with building a prototype and testing a model.

A method for determining the heat transfer and water vapour permeability of patient support systems.

The formation of pressure ulcers can be exacerbated by a breakdown in the integrity of the patient's skin caused by poor maintenance of the skin microclimate. Patient support systems (PSSs-specialised beds, mattresses, chairs, cushions and pads) play an important role in the dissipation of heat and moisture away from the skin/support interface which is necessary in order to maintain the physiological skin microclimate. This paper reports a laboratory method and theory for the simultaneous measurement of the heat and water vapour dissipating properties of PSSs. The results demonstrate that the method is extremely selective, exhibiting very significant differences between the PSSs tested. It also shows that assessing PSS covers independently does not necessarily indicate the overall performance of the complete PSS.

Five-year agreement for equipment acquisition.

A three-hospital system in western Canada had decided to replace its old imaging processing equipment but wrestled with the most effective way to purchase it. As Mr. Clark describes in this practical guide to the process, the hospitals combined their buying power, negotiated a long-term agreement and found a supplier committed to total quality management.

Identification of functioning sweat pores and visualization of skin temperature patterns in X-linked hypohidrotic ectodermal dysplasia by whole body thermography.

In this preliminary study, non-invasive infrared thermography has been used to visualize individual sweat pores and whole body skin temperature patterns in subjects with X-linked hypohidrotic ectodermal dysplasia (XHED) and normal controls. The findings in eight obligate heterozygotes and four affected males were compared to six normal female controls and to six non-manifesting females at risk for carrier status. Sweat secretion from individual pores in circumscribed areas was imaged using a high spatial resolution SPRITE infrared detector system working in the 8-14 microns band. In seven out of eight obligate heterozygotes, skin areas devoid of active sweat glands were found on the face, the hands or the trunk. Tear front movement over the cornea was also visualized and abnormal patterns were identified in obligate heterozygotes. Whole body skin temperature patterns, obtained with an Agema 780 Medical Thermovision system, identified abnormal skin temperature distributions, including characteristic aberrant "cascade" back patterns, in obligate carriers. Two out of six "at risk" females had skin temperature patterns comparable with obligate heterozygotes and we have tentatively concluded that they are carriers. Thermal imaging may be used for the examination of "at risk" non-manifesting females in families with a single affected male. The results of this study suggest that the random X-inactivation in females with XHED, as well as producing relatively large skin areas with sweat pore aplasia, is also associated with abnormal temperature patterns that are consistent with altered peripheral vascular perfusion.

Open fronted safety cabinets in ventilated laboratories.

Open fronted Class I and II microbiological safety cabinets (MSCs) are required by the British Standard 5726 to provide similar levels of operator protection (viz. 10(5). In laboratories that are naturally ventilated large numbers of both types of cabinets have been shown to exceed this requirement consistently over a number of years. The designs of some mechanically ventilated laboratories, however, produce excessive turbulence and draughts that can prejudice containment at the front aperture. On-site commissioning tests to determine operator protection factor are now well established and are recognized as being essential to the setting up of all open fronted cabinets in both ventilated and unventilated laboratories. This paper shows that where environmental conditions induce unsatisfactory cabinet containment, adjustments to air supply and exhaust systems can be made which will enable both Class I and II cabinets to produce operator protection factors in excess of 10(5). When compatibility is achieved between the local environment and the cabinets it is demonstrated that disturbances at the front aperture, caused by operator working procedures or by disturbances due to personnel movement within the room, have similar effects on both Class I and II cabinets. Once performance levels have been satisfactorily achieved, regular containment testing has shown that consistent performance can be maintained. These aspects of open fronted safety cabinet performance are discussed in relation to ventilated laboratories suitable for work with the human immunodeficiency virus (HIV). Of paramount importance in the future is the necessity to design laboratory air systems that will be compatible with satisfactory safety cabinet performance--a relatively new requirement in ventilation system specifications.

A pyroelectric thermal imaging system for use in medical diagnosis.

The value of infra-red thermography in a number of pathologies, notably rheumatology and vascular diseases, is becoming well established. However, the high cost of thermal scanners and the associated image processing computers has been a limitation to the widespread availability of this technique to the clinical community. This paper describes a relatively inexpensive thermographic system based on a pyroelectric vidicon scanner and a microcomputer. Software has been written with particular reference to the use of thermography in rheumatoid arthritis and vasospastic conditions such as Raynaud's phenomenon.

Electronic particle counting for evaluating the quality of air in operating theatres: a potential basis for standards?

Airborne particle counting in eight size ranges (0.5- greater than 20 microns), by computerized electronic equipment, was compared with the numbers of bacteria-carrying particles (BCP) assessed by slit sampling in ultra-clean and turbulently ventilated operating theatres. In the ultra-clean theatre the number of particles of 5-7 microns size range correlated with BCP while peaks in the numbers of particles less than 3 microns and greater than 15 microns corresponded with activity. Comparative relationships also occurred in the turbulently ventilated theatre but the use of this equipment in that environment cannot yet replace counts of airborne bacteria. We consider that electronic particle counting in the 0-20 microns size range may be used to judge the performance of a clean air operating theatre distribution system, including efficiency and integrity of the filter/seal systems and the presence or absence of entrainment of bacteria and other particles. The sampling techniques and analysis of particle concentration results described here may be a suitable basis for standards.

Botulinum toxin: a treatment for facial asymmetry caused by facial nerve paralysis.

Injury to the frontal or other facial nerve branches can result in an asymmetry that can be very distressful to both patient and surgeon. This is especially true following cosmetic procedures such as rhytidectomy. We propose a means to create temporary symmetry while awaiting the possible return of nerve function. Botulinum neurotoxin causes a muscle paralysis lasting for approximately 3 months, and it is well established as the preferred treatment for blepharospasm. A case is presented in which botulinum toxin type A was injected into the opposite functioning frontalis muscle of a patient with unilateral frontal nerve paralysis. The patient experienced satisfactory relief of the asymmetry caused by onesided forehead wrinkling and brow elevation. Botulinum toxin therapy should be considered for both temporary and permanent facial asymmetries due to facial nerve paralysis as well as spasm.

Modification of the leader protein (Lb) of foot-and-mouth disease virus.

Translation of foot-and-mouth disease virus RNA for extended periods in rabbit reticulocyte lysates results in the appearance of a previously undescribed protein. A protein with similar properties can also be detected in BHK cells at late times after virus infection. Specific immunoprecipitation has shown that this protein (Lb') is closely related to the smaller of the two leader proteins, Lb, although it migrates with an apparently higher Mr in SDS-polyacrylamide gels. The conversion of Lb to Lb' can be mimicked by treatment with carboxypeptidase B. It is suggested that C-terminal trimming of Lb to produce Lb' results in an increase in negative charge and is responsible for its slower migration in SDS-PAGE.

A synthetic peptide which elicits neutralizing antibody against human rhinovirus type 2.

Synthetic peptides corresponding to six predicted immunogenic sites on human rhinovirus type 2 (HRV2) have been tested for their reactivity with an anti-virion antibody and for their ability to elicit neutralizing antibody. Four of the peptides reacted with HRV2 antiserum in an indirect ELISA. Rabbit antisera produced to three of these four peptides, one each from VP1, VP2 and VP3, reacted with the virus in an indirect ELISA and with the corresponding proteins by Western blotting. Furthermore, antiserum to one of the peptides, designed to cover the neutralization epitope NIm-II on VP2, not only reacted well in a sandwich ELISA and in an immunoprecipitation test but also neutralized virus infectivity.

The genome-linked proteins of aphthoviruses: specific immunoprecipitation of the three species detected on virus RNA and identification of possible precursors.

Synthetic peptides have been made corresponding to the C-terminal portion of each of the three presumptive genome-linked proteins (VPgs) of foot-and-mouth disease virus type A10. Antisera against each of these peptides efficiently precipitated only the homologous VPg, and the reactions were inhibited by prior absorption with homologous, but not heterologous synthetic peptide. The peptide antisera precipitated a number of proteins from infected cell extracts with mol. wt. of 100, 84, 56, 36, 27, 25 and 20, all X 10(3); all these reactions were inhibited by absorption with homologous peptide, indicating that they were probable precursors of VPg. The relationship between these proteins is at present unclear.

An electroblotting technique for assessing the integrity of the major immunogenic protein in foot-and-mouth disease virus vaccines.

A method has been developed whereby VP1, the major immunogenic protein of foot-and-mouth disease virus can be detected after electroblotting on nitrocellulose paper. Proteins can be examined in unfractionated virus harvests and after formulation as aluminium hydroxide-adjuvanted vaccines. The limit of detection is approximately 10 ng of VP1 and up to 20 samples can be analysed simultaneously. The technique allows the integrity of VP1 to be examined in fully formulated vaccines.