Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included

A Study of Student Environmental Knowledge and Attitudes in Selected High Schools in the Permian Basin Region of Texas

This study is a partial replication of research conducted by Perkes (1973). The problem in this study is to assess the magnitude of the relationship between student knowledge of the environment, student gender, grade level, and size of school attended; and the level of attitudinal differences between students based upon student gender, grade level, and the size of school that students attend. Methods of data collection include the use of an environmental knowledge and attitude inventory used by Perkes (1973) and modified by Hardy and Fox (1976). This thesis includes an added dimension, a survey of environmental education curricula in the Permian Basin Region of Texas

Influence of wing span on the aerodynamics of wings in ground effect

A computational fluid dynamics study of the influence of wing span has been conducted for an inverted wing with endplates in ground effect. Aerodynamic coefficients were determined for different spans at different ground clearances, highlighting a trend for shorter spans to delay the onset of both separation and resulting loss of negative lift. The vortices at the wing endplates were not observed to change significantly in terms of strength and size; thus, at shorter spans, their influence over a larger percentage of the wing helped the flow stay attached and reduced the severity of the adverse pressure gradient which invokes separation at greater spans. Consequently, it was shown that, compared to a large-span wing, a wing with a shorter span may have a lower lift coefficient but can operate closer to the ground before performance is adversely affected

Implications of compressibility effects for Reynolds-scaled testing of an inverted wing in ground effect

The influence of compressibility around an isolated inverted wing at a fixed Reynolds number was examined as relevant to the issue of wind tunnel scaling effects. Three-dimensional simulations were conducted for low ground clearances, at: full scale and a Mach number of 0.088, at 50% scale at Mach 0.176, and at 25% scale at Mach 0.352. As the scale was reduced, the increasing peak local Mach number between the wing and the ground resulted in a higher propensity of the flow to separate towards the trailing edge, and for incompressible or full-scale CFD to underestimate the lift and drag coefficients by an ever-increasing margin. The lower vortex path was less affected. The results suggest that compressible CFD of a scale experiment ought to be conducted at the same Reynolds number and Mach number as the tunnel test for the best possible correlation at free-stream Mach numbers beyond 0.15

Identifying predictors for focused CT scanning in the ED

Background Appropriate imaging for major trauma patients, in particular deciding between imaging of a single body region or whole body CT (WBCT), is an important aspect of clinical decision making in these patients. This study aimed to identify predictors of injury to a single scan region in major trauma patients. Discussion These findings suggest that patients with examination findings isolated to a single body region may only need isolated imaging to the affected area. These factors, used in conjunction with a clinical decision rule for WBCT may help decide on the appropriate imaging for patient who do not need WBCT imaging

Variant anatomy of the right portal vein in a black Kenyan population

Surface mapping of the liver before invasive procedures depends on a proper understanding of its segmental vasculature. The right portal vein ramification and lengths show marked variations and these mostly involve its right posterior sectoral branch. Their incidence is variable among populations and altogether undocumented among Africans. One hundred livers obtained during autopsies and dissections at the Department of Human anatomy, University of Nairobi, were used in this study. Gross dissection was done to reveal and determine the branching pattern of the right portal vein and the origin of the right posterior sector branch. The lengths of the right portal vein were also measured and recorded. When present, the right portal vein terminated by bifurcation in 61% of the cases, trifurcated in 20.8% and quadrifircated in 18.2%. Its length was between 0.5cm and 4cm. The right posterior sector vein was given off the main portal vein in 34 cases, the common left portal vein trunk in 15 cases, and the right portal vein in 42 cases. In 9 cases, it was not observed at the porta hepatis. We report significant different incidences of the variant anatomy of the right portal vein compared to those found in previous studies and this should be borne in mind when doing surgical interventions.Keywords: Segmentectomy, transjugular, Surface mapping, Bifurcatio

Use of rapid diagnostic tests in malaria school surveys in Kenya: does their under-performance matter for planning malaria control?

Malaria rapid diagnostic tests (RDTs) are known to yield false-positive results, and their use in epidemiologic surveys will overestimate infection prevalence and potentially hinder efficient targeting of interventions. To examine the consequences of using RDTs in school surveys, we compared three RDT brands used during a nationwide school survey in Kenya with expert microscopy and investigated the cost implications of using alternative diagnostic approaches in identifying localities with differing levels of infection. Overall, RDT sensitivity was 96.1% and specificity was 70.8%. In terms of classifying districts and schools according to prevalence categories, RDTs were most reliable for the 40% categories and least reliable in the 1-4.9% category. In low-prevalence settings, microscopy was the most expensive approach, and RDT results corrected by either microscopy or polymerase chain reaction were the cheapest. Use of polymerase chain reaction-corrected RDT results is recommended in school malaria surveys, especially in settings with low-to-moderate malaria transmission