A research report submitted to the Faculty of Medicine, University of Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Medicine in the branch of Anaesthesia. / Spinal anaesthesia for Caesarean section is associated with an unacceptably high incidence of hypotension despite the administration of an intravenous fluid preload and the use of uterine displacement. The theoretical benefits of preventing hypotension as opposed to treating it as it occurs are the avoidance of considerable maternal discomfort, a reduced risk of serious cardiovascular or respiratory depression and the avoidance of transient foetal asphyxia. The use of prophylactic intramuscular ephedrine prior to spinal anaesthesia has been recommended but not well studied. The advantages of the intramuscular route for ephedrine administration are its simplicity and its favourable pharmacokinetic profile. Cardiovascular support is sustained throughout the surgery and into the post operative period. Opposition to the use of intramuscular ephedrine in the prevention of hypotension is based on two studies in which spinal anaesthesia was not used [1,2]. These studies showed an unacceptably high incidence of hypertension, a deleterious effect on foetal gas exchange and a lack of efficacy when intramuscular ephedrine was used in epidural and general anaesthesia respectively. This research report describes a randomised, double blind, interventional study designed to assess the safety (prevalence of hypertension, tachycardia or foetal compromise) and efficacy (prevalence of hypotension) of 37,5mg of ephedrine given prior to spinal anaesthesia for Caesarean section. Forty patients who had given informed consent were entered into the study. Blood pressures and pulse rates were recorded for 90 minutes after ephedrine administration, samples of umbilical venous blood were collected and Apgar scores assessed. This study found that giving 37,5mg of intramuscular ephedrine prior to spinal anaesthesia was safe from a maternal point of view in that it was not associated with reactive hypertension or tachycardia. When the ephedrine was given 10 minutes prior to induction of the spinal the technique proved to be effective in reducing the incidence and severity of hypotension. When used in the above manner the technique was not associated with foetal depression or acidosis. / WHSLYP2016

<p>The use of gabions means a reduced amount of filling material in the road section and a more narrow construction. Also the use of limestone cement columns can be reduced. All together this results in lower costs. The columns stand for about 55% of the total costs for the road. If gabions are used you can reduce the total costs with over 10%.</p>

The use of gabions means a reduced amount of filling material in the road section and a more narrow construction. Also the use of limestone cement columns can be reduced. All together this results in lower costs. The columns stand for about 55% of the total costs for the road. If gabions are used you can reduce the total costs with over 10%.

A new definition of the diffusion coefficient for use in reactor physics calculations is evaluated in this thesis. It is based on naturally flux-limited diffusion theory (FDT), sometimes referred to as Levermore-Pomraning diffusion theory. Another diffusion coefficient more loosely based on FDT is also evaluated in this thesis. Flux-limited diffusion theory adheres to the physical principle of flux-limiting, which is that the magnitude of neutron current is not allowed to exceed the scalar flux. Because the diffusion coefficients currently used in the nuclear industry are not flux-limited they may violate this principle in regions of large spatial gradients, and because they encompass other assumptions, they are only accurate when used in the types of calculations for which they were intended. The evaluations were performed using fine-mesh diffusion theory. They are in one spatial dimension and in 47, 4, and 2 energy groups, and were compared against a transport theory benchmark using equivalent energy structures and spatial discretization. The results show that the flux-limited diffusion coefficient (FD) outperforms the standard diffusion coefficient in calculations of single assemblies with vacuum boundaries, according to flux- and eigenvalue-errors. In single assemblies with reflective boundary conditions, the FD yielded smaller improvements, and tended to improve only the fast-group results. The results also computationally confirm that the FD adheres to flux-limiting, while the standard diffusion coefficient does not.

This study explores the spatial-temporal patterns of Section 404 permitting program under the Clean Water Act and examines its impact on mean and peak annual streamflow. The study area consists of 47 sub-basins that are delineated based on USGS streamflow gauges. These sub-basins span from the southern portion of coastal Texas to the easternmost portion of coastal Texas. Descriptive, spatial and spatial-temporal statistical methods are used to explore patterns in Section 404 permitting between 1996 and 2003. The effects of Section 404 permit types on mean and peak annual streamflow over the same 8 year period are also statistically modeled with a host of other relevant control variables. Exploratory analyses of Section 404 permits demonstrated characteristics that were indicative of suburban and, to a larger extent, exurban development. Explanatory analyses of the effects of Section 404 permitting on mean and peak streamflow showed that Section 404 permits increase both measures. These increases were minimal on a per-permit basis but have the ability to accumulate over time and result in much larger increases. Section 404 permits also displayed an ordered effect based on the permit type. Permit types that represent larger impacts had larger effects. The effects of permits of streamflow followed a descending pattern of Individual permits, Letters of Permission, Nationwide permits, and General permits. This “type of permit impact” supports the use of this measure as an indicator of wetland impact and loss and corroborates previous studies that have incorporated this measure.

published_or_final_version / abstract / toc / Clinical Psychology / Master / Master of Social Sciences

Ultrasound elevation beamwidth is the out of plane thickness causing image artefacts normally appearing around anechoic areas in the medium. These artefacts could also cause uncertainties in localizing objects (such as a surgical needle) in the ultrasound image slices. This thesis studies the clinical significance of elevation beamwidth artefacts in needle insertion procedures. A new measurement device was constructed to measure the transrectal ultrasound elevation beamwidth. The beam profiles of various lateral and axial distances to the transducer were generated. It is shown that the ultrasound elevation beamwidth converges to a point within its focal zone close to the transducer. This means that the transrectal ultrasound images have the best resolution within the focal zone of the ultrasound close to the transducer. It is also shown that the ultrasound device settings have a considerable impact on the amount of beamwidth artefacts. Needle tip localization error was examined for a curvilinear transrectal ultrasound transducer. Beveled prostate brachytherapy needles were inserted through all holes of a grid template orthogonal to the axial beam axis. The effects of device imaging parameters were also investigated on the amount of localization error. Based on the developed results, it was found that the imaging parameters of an ultrasound device have direct impact on the amount of object localization error from 0.5 mm to 4 mm. The smallest localization error occurs laterally close to the center of the grid template, and axially within the beam’s focal zone. Similarly, the largest localization error occurs laterally around both sides of the grid template, and axially within the beam’s far field. Using the ultrasound device with appropriate imaging settings could minimize the effects of these artefacts. We suggest to reduce the gain setting of the ultrasound device. This will reduce the energies assigned to the off-axis beams and as a result, the elevation beamwidth artefacts are minimized. / Thesis (Master, Computing) -- Queen's University, 2011-09-01 15:27:43.098

Thesis (M.Med.Sc.)--University of Hong Kong, 2003. / Also available in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1980. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 63-65).

A Thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. 14th October 2016 in Johannesburg / Poorly controlled pain following caesarean section surgery can have a debilitating effect on the physical and emotional well being of a woman during the post-operative period. Good intra-operative anaesthetic management during caesarean section surgery is requisite to improve post-operative analgesia, and thereby contribute to the well being of the patient. In South Africa (SA) there are currently no national obstetric anaesthesia practice guidelines. Anaesthetic service providers therefore rely on knowledge acquired during their anaesthetic training and recommendations from international guidelines (which may not be applicable in SA). In order to establish a reference standard of anaesthetic care for obstetric patients in SA, a semi-structured interview was conducted with the heads of department and/or their representatives from the eight anaesthesiology academic departments in SA in 2012. The experts provided recommendations on the intra-operative anaesthetic management of patients for elective and emergency caesarean sections, as well as the post-operative monitoring and analgesic management of these patients. The recommendations were based on the experts’ understanding of the uniquely local healthcare environment in SA. Following the establishment of the SA reference standard, a national survey of anaesthetic service providers was conducted in 2014 to establish what the practises are in South Africa for caesarean section anaesthetics. Ninehundred- and-thirty-three survey responses were analysed, which equated to a 58% response rate. The majority of anaesthesia providers (97.8%) perform single shot spinal anaesthesia for caesarean sections. Thirty percent of respondents chose to use Quincke spinal needles, despite the increased risk of this needle causing post-dural puncture headaches (PDPH). The preferred local anaesthetic drug was 0.5% bupivacaine with dextrose, and fentanyl was the most commonly used additive agent, as opposed to common international practice, which advocates morphine. The survey also revealed that 58% of doctors work in hospitals that do not have a post-operative monitoring protocol for patients following caesarean section surgery. This contrasts to recommendations suggested by the national experts regarding patient monitoring requirements. A clinical trial was then conducted to compare the analgesic efficacy of two different doses of intrathecal morphine (50μg and 100μg) with 25μg fentanyl. Patients in both morphine treatment groups had significantly lower postoperative opioid requirements than patients in the fentanyl group. The pain numerical rating scale (NRS) scores were however not statistically different and there was also no difference in the side effects profile or emotional parameters measured, between the groups. This study highlights the differences in the recommended practise of obstetric anaesthesia in SA compared to other countries and demonstrates how obstetric anaesthesia is practised in SA. The final component of this study has demonstrated how international best practices can be easily implemented in SA to improve the anaesthetic care of the obstetric patient. / MT2017