From videocassette to video stream: Issues involved in re‐purposing an existing educational video

Conventional video recordings can be converted into video streams but the process can be complex and problematic. The authors’ experience of re‐purposing an existing video, Back Care for Health Professionals, for streaming is used to illustrate what was involved and to highlight the important issues. Financial, legal, technical and pedagogic issues are examined

Remote sensing applied to land use and erosion hazard studies in Jamaica

The northern half of the parish of St. Catherine in Jamaica was selected as a test area to study, by means of remote sensing, the problems of soil erosion in a tropical environment. An initial study was carried out to determine whether eroded land within this environment could be successfully interpreted and mapped from the available 1: 25,000 scale aerial photographs. When satisfied that a sufficiently high percentage of the eroded land could be interpreted on the aerial photographs the main study was initiated. This involved interpreting the air photo cover of the study area for identifying and classifying land use and eroded land, and plotting the results on overlays on topographic base maps. These overlays were then composited with data on the soils and slopes of the study area. The areas of different soil type/slope/land use combinations were then measured, as was the area of eroded land for each of these combinations. This data was then analysed in two ways. The first way involved determining which of the combinations of soil type, slope and land use were most and least eroded and, on the basis of this, to draw up recommendations concerning future land use. The second analysis was aimed at determining which of the three factors, soil type, slope and land use, was most responsible for determining the rate of erosion. Although it was possible to show that slope was not very significant in determining the rate of erosion, it was much more difficult to separate the effects of land use and soil type. The results do, however, suggest that land use is more significant than soil type in determining the rate of erosion within the study area

Evaluation of a hydrographic technique to measure on-farm water storage volumes

Digital terrain models of on-farm water storages are required to assist in accurately measuring the on-farm water balance and water use efficiency components including storage capacity, inflow, seepage, evaporation and discharge volumes. A hydrographic surveying system combining a high-precision global positioning system (GPS) and a low-cost depth sounder was developed to facilitate the creation of a digital terrain model. The system was validated by comparing the hydrographic terrain model and volume measurements against both a traditional real time kinematic (RTK) land based survey and independent lead line depth measurements. Flat bottomed storage volumes were measured with errors of less than 1 percent using the hydrographic survey technique. A major proportion of the error in small storages was found to be associated with the ability to accurately identify the inflection point between the banks and floor of the storage. However, for larger storages, errors were primarily related to density of sampling points within the storage floor area. Recommendations are provided regarding the appropriate measurement procedures, including sampling point density, for a range of storage sizes

The Rationality Uninformed Electorate: Some Experimental Evidence

This essay reports on a series of twenty four election experiments in which voters are allowed to decide between voting retrospectively and purchasing contemporaneous information about the candidate challenging the incumbent. Each experiment consists of a series of election periods in which dummy candidates choose spatial positions which represent either their policy while in office or a promise about policy if elected. Subjects (voters) are told the value to them of the incumbent's policy, but they must decide, prior to voting, whether or not to purchase information about the value of the challenger's promise. In general, our data conform to reasonable expectations: voters purchase less information and rely more on retrospective knowledge when the candidates' strategies are stable, and their likelihood of purchasing information during periods of instability is tempered by the likelihood that their votes matter, by the reliability of the information available for purchase, and by the degree of instability as measured by changes in each voter's welfare

Validation du « Hunt Squash Accuracy Test » pour évaluer la performance des joueurs dans l'exécution de leurs coups

This study examined the validity of the Hunt Squash Accuracy Test (HSAT) for predicting within-game shot performance and tournament rank. Shots from eight male junior squash players performing the HSAT and tournament match-play were analysed. A typical-error analysis from repeated trials showed the HSAT to be very reliable (1.82%). HSAT rank had significant correlations (p < 0.05) to tournament rank (r = 0.98) and tournament shot success (r = 0.95). HSAT score showed significant correlations to the percentage of winning shots during match-play (r = 0.88). HSAT shots with significant correlations to successful match-play shots were backhand-drive (r = 0.92) and backhand-volley (r = 0.97). These results suggest the HSAT is a valid method of assessing the accuracy and performance of junior squash players. It could potentially be used to track shot improvements and predict match-play performance

Very early versus delayed mobilization after stroke: systematic review and meta-analysis

No abstract available

A QUANTITATIVE ANALYSIS OF SQUASH SHOT ACCURACY

The purpose of this study was to examine the validity of the Hunt Squash Accuracy Test (HSAT) for predicting within-game performance on specific shot types. A correlation analysis compared the accuracy of specific shots during tournament match-play to the accuracy of the corresponding shot type in the HSAT. The correlation of the overall HSAT score against tournament rank was significantly large (0.95), as were the total % shot accuracy (0.90), total % backhand (BH) accuracy (0.94) and total % forehand (FH) accuracy (0.77) correlations. The only specific HSAT shot types with significantly large correlations to the corresponding match-play shots were; BH straight drive (0.92) and BH straight volley (0.97). The remaining shot types; boast, volley-drop and drops all showed non-significant correlations on both the BH and FH sides

Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

The original publication is available at http://www.sajs.co.za/A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infrared (NIR) lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from deexcitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar