Introduction A protocol has been devised in which a 20ml mixture of hyperbaric bupivacaine and fentanyl is prepared in a multi-dose syringe, from which aliquots are withdrawn into individual sterile syringes for use in spinal anaesthesia. The risk of microbial contamination of these multi-dose syringes is unknown and this study was designed to assess such risk. Methodology In this pilot study, each syringe was prepared using non-aseptic technique to contain a mixture comprising Fentanyl 10 μg.ml-1, Bupivacaine 4mg.ml-1and Dextrose 64mg.ml-1, with a total volume of 20ml. Syringes were then allocated to pairs. Aliquots were withdrawn hourly from one syringe of each pair for a twelve-hour study period, whilst the other syringe was sampled only at the beginning and end of the same period. All aliquots were withdrawn using standard aseptic technique in an operating theatre environment. For each syringe pair, both samples from the control syringe and four of the samples from the multi-dose syringe were submitted for microbiological culture. Results Of the 120 samples taken, one sample was excluded. Of the remaining 119 samples submitted for microbiological investigation, only one yielded growth. This sample had been taken from a multi-dose syringe at the beginning of the study period. Subsequent samples withdrawn from the same syringe were found to be sterile. The organism which had been cultured from this sample was Staphylococcus aureus (S. aureus). Conclusion It is possible that the culture medium which yielded the microbial growth was contaminated, which would explain why subsequent samples from the same syringe were sterile. Alternatively, bupivacaine is known to be strongly antimicrobial against some pathogens and it is conceivable that there may have been initial contamination of the syringe by S. aureus, which was inhibited by the bupivacaine to produce subsequent sterile samples. Whilst this may suggest that the use of multi-dose syringes for spinal anaesthesia could be safe, in light of the inconclusive result, further investigation is warranted.

The continuation of conductive temperature fields is being considered. The continuation of a field involves the extrapolation of a field known over a limited domain to an adjacent domain in such a way that it satisfies the heat conduction differential equation and other imposed constraints. Continuations forward in time and toward the interior of the space from the constraining initial and boundary conditions are expressed analytically as convolution integrals. Solutions are approximated using linear filter methods in real and transform spaces. The inverse problems of continuation toward the constraining conditions are expressed in real space as power series of derivatives. Solutions are approximated as convolution filtering operations. Variational methods are also used to solve problems which do not yield to convolution filtering operations. The suitability of these approximation methods is shown in two ways: (1) the frequency response of the derived convolution coefficients are compared with the analytic transfer functions; and (2) the methods are applied to artificial test cases. These field continuation methods provide a tool for the interpretation of observational temperature data. Several examples of field data are treated using these techniques; (1) A case of the temperature inversion observed in a geothermal borehole is explained by a transient flow of thermal water along a narrow horizontal fracture; (2) Soil temperature data are treated to determine the in situ thermal diffusivity and show that departures from conductive conditions are accounted for by evaporative effects; (3) Shallow borehole temperature data which exhibit the nonstationary effects of the annual cycle are shown to be influenced by convective effects in the soil. / Graduation date: 1976

Thèse de doctorat : Physique : Metz : 2007. / Thèse soutenue sur ensemble de travaux. Bibliogr. f. 123-124. Acronymes f. 5.

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An evaluation of methods for predicting turbulent heat transfer in rough pipes has been made with the intention of obtaining a better understanding of the transfer processes involved and of providing a general design equation, valid for all types of roughness shapes and distributions. The equations of Martinelli, Nunner, and Mattioli, along with an empirical method suggested by Epstein, have been tested using the available experimental data. In addition, particular attention has been given to a proposed method which makes use of the velocity profile equations of Rouse and von Karman in Lyon's fundamental equation for the Nusselt number. The results indicate that the proposed method is not successful, largely because of ignorance of velocity conditions near the walls of rough pipes. Mattioli's equation also does not give a satisfactory correlation of experimental results. Epstein's empirical method, which, in the pertinent dimensionless groups, uses friction velocity and equivalent sand-roughness height of the roughness elements in place of the average fluid velocity and the pipe diameter, respectively, shows promise but requires further investigation. Nunner's equation and Martinelli's (simplified) equation give good prediction of the experimental results and are recommended for use at present, providing 0.5 < Pr < 1.0. The success of these latter equations gives support to the hypothesis that the fluid adjacent to a rough wall is probably in laminar motion. Using Nunner's model of the flow conditions in rough pipes, equations have been derived for predicting temperature profiles from velocity profile data. Generally, the absolute agreement between predicted profiles and Nunner’s experimental profiles is good, but the influences of Re and especially f are not too well accounted for. Nunner's conclusion that temperature and velocity profiles in rough pipes are not similar is substantiated by the results. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

LD2668 .T4 1940 H34 / Master of Science

published_or_final_version / Physics / Master / Master of Philosophy

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