Five years of peripheral percutaneous transluminal angioplasty : the St Luke’s Hospital experience

This article reviews the first series of 54 cases of Percutaneous Transluminal Angioplasty on the peripheral vasculature performed at the Radiological/Surgical Department at St. Luke’s Hospital, Malta, over a five year period. After describing in detail the technique used, the indications and the objective criteria utilised for assessment are reviewed and analysed. The two year patency rate for femoro-popliteal and iliac stenoses was 93% and 86% respectively, while for corresponding occlusions, the figures were 42% and 0% respectively. Thus, while the results were very encouraging for femoro-popliteal stenoses and occlusions, they were unacceptable for iliac occlusions. As expected the major risk factors were smoking, diabetes mellitus and associated ischaemic heart or cerebrovascular disease. This series had no mortality and there was minimal morbidity, mainly at the site of arterial access. Elective surgery for iliac re-stenosis was only required in one patient.peer-reviewe

Sensory Augmentation for Navigation in Difficult Urban Environments by People With Visual Impairment

Independent mobility in completing such tasks as walking through a town centre is taken for granted by well-bodied individuals. However, for those with a disability such as impairment of vision, mobility and navigation can become challenging tasks not easily undertaken. The barriers to access for blind and partially sighted individuals are increased when familiar navigational cues are removed in difficult urban environments such as Shared Space. The research consisted of investigating methods of navigation employed by people with visual impairment and designing a device to restore confidence to this group so as to lower the barriers of access to such environments. Investigation was carried out through the deployment of a questionnaire; discussions with groups representing blind and partially sighted people; and a site visit to Shared Space environments. Statistical analysis was carried out on the results of the questionnaire to ascertain the navigational habits of blind and partially sighted individuals in different environments. From the analysis and the results of the discussions and site visit it was established that it would be socially acceptable to design a secondary aid to navigation that would complement the primary aids of long cane or guide dog. A concept experiment was carried out to test the idea that knowledge about changes in surface colour could help with navigation. A prototype device that could be used by individuals with visual impairment to increase their confidence when navigating a difficult environment was designed, built and tested. Different programming methods were researched and trialled to effectively use machine vision to provide a solution to analyse video feed from a passive camera and return useful information to a blind or partially sighted user. The device was tested indoors and outdoors and found to be effective at detecting changes in surface colour. Further work is needed to run the software on a more compact platform such as a mobile phone, but initial results show that the concept is viable and that the barriers that present to blind and partially sighted people navigating difficult urban environments can be much reduced through the use of this technology

The use of artificial neural networks in classifying lung scintigrams

An introduction to nuclear medical imaging and artificial neural networks (ANNs) is first given. Lung scintigrams are classified using ANNs in this study. Initial experiments using raw data are first reported. These networks did not produce suitable outputs, and a data compression method was next employed to present an orthogonal data input set containing the largest amount of information possible. This gave some encouraging results, but was neither sensitive nor accurate enough for clinical use. A set of experiments was performed to give local information on small windows of scintigram images. By this method areas of abnormality could be sent into a subsequent classification network to diagnose the cause of the defect. This automatic method of detecting potential defects did not work, though the networks explored were found to act as smoothing filters and edge detectors. Network design was investigated using genetic algorithms (GAs). The networks evolved had low connectivity but reduced error and faster convergence than fully connected networks. Subsequent simulations showed that randomly partially connected networks performed as well as GA designed ones. Dynamic parameter tuning was explored in an attempt to produce faster convergence, but the previous good results of other workers could not be replicated. Classification of scintigrams using manually delineated regions of interest was explored as inputs to ANNs, both in raw state and as principal components (PCs). Neither representation was shown to be effective on test data

A shrinking core model for steam hydration of CaO-based sorbents cycled for CO2 capture

Calcium looping is a developing CO2 capture technology. It is based on the reversible carbonation of CaO sorbent, which becomes less reactive upon cycling. One method of increasing the reactivity of unreactive sorbent is by hydration in the calcined (CaO) form. Here, sorbent has been subjected to repeated cycles of carbonation and calcination within a small fluidised bed reactor. Cycle numbers of 0 (i.e., one calcination), 2, 6 and 13 have been studied to generate sorbents that have been deactivated to different extents. Subsequently, the sorbent generated was subjected to steam hydration tests within a thermogravimetric analyser, using hydration temperatures of 473, 573 and 673 K. Sorbents that had been cycled less prior to hydration hydrated rapidly. However, the more cycled sorbents exhibited behaviour where the hydration conversion tended towards an asymptotic value, which is likely to be associated with pore blockage. This asymptotic value tended to be lower at higher hydration temperatures; however, the maximum rate of hydration was found to increase with increasing hydration temperature. A shrinking core model has been developed and applied to the data. It fits data from experiments that did not exhibit extensive pore blockage well, but fits data from experiments that exhibited pore blockage less well