Noninvasive monitoring of DNAPL migration through a saturated porous medium using electrical impedance tomography.

Electrical impedance tomography (EIT) was used to monitor the movement of a fluorinated hydrocarbon dense nonaqueous phase liquid (DNAPL) through a saturated porous medium within a laboratory column. Impedance measurements were made using a horizontal plane of 12 electrodes positioned at regular intervals around the centre of the column. A 2D inversion algorithm, which incorporated the cylindrical geometry of the column, was used to reconstruct resistivity and phase images from the measured data. Differential time-lapse images of DNAPL movement past the plane of electrodes were generated by the cell-by-cell subtraction of resistivity and phase baseline models from those associated with the DNAPL release stage of the experiment. The DNAPL pulse was clearly delineated as resistive anomalies in the differential time-lapse resistivity images. The spatial extent of the resistive anomalies indicated that in addition to vertical migration, some lateral spreading of the DNAPL had occurred. Residual contamination could be detected after quasi-static conditions were reestablished. Residual DNAPL saturation was estimated from the resistivity model data by applying Archie's second equation.Despite significant measured phase changes due to DNAPL contamination, the differential phase images revealed only weak anomalies associated with DNAPL flow; these anomalies could be seen only in the initial stages of the experiment during peak flow through the plane of electrodes.

Coronary artery bypass grafting with cardiopulmonary bypass versus off-pump cardiopulmonary bypass grafting: does eliminating the pump reduce morbidity and cost?

BACKGROUND: Cardiopulmonary bypass (CPB) may contribute to the complications and cost of coronary artery bypass grafting (CABG). Off-pump CABG (OPCAB) allows coronary revascularization without CPB. We hypothesized that OPCAB provides satisfactory graft patency while reducing complications and cost compared with CABG with CPB. METHODS: We prospectively followed 80 patients undergoing CABG: 40 patients undergoing OPCAB and 40 patients undergoing CABG with CPB. OPCAB patients underwent angiography within 48 hours of surgery to determine early graft patency. Incidence of complications, length of stay, and costs were recorded for each patient. The influence of the number of vessels bypassed was analyzed. RESULTS: OPCAB patients (n = 40) underwent grafting of 2.7 +/- 0.7 vessels per patient compared with 3.6 +/- 0.8 vessels per patient in the CABG with CPB group (n = 40) (p < 0.0001). Angiography demonstrated 105 of 108 (97%) of grafts were patent in the OPCAB group. Incidence of complications, length of stay, and costs did not differ between the OPCAB and CABG with CPB groups. Number of vessels grafted showed a positive correlation to total costs in both groups. CONCLUSIONS: While OPCAB provided satisfactory early graft patency, there was no significant difference between OPCAB and CABG with CPB with regard to cost, length of stay, or incidence of complications. In this study, eliminating CPB did not reduce morbidity or cost after CABG.

Immediate colposcopy or cytological surveillance for women with mild dyskaryosis: a cost effectiveness analysis.

BACKGROUND: The aim of the study was to compare the cost effectiveness of immediate diagnosis and treatment of mild dyskaryosis compared with the usual policy of cytological surveillance. METHODS: A cost effectiveness analysis was carried out alongside a randomized clinical trial. RESULTS: Immediate diagnosis and treatment increased total costs by 50 per cent from 54.42 pounds per treated woman [95 per cent confidence interval (CI) 48.85 pounds-59.98 pounds] in the surveillance group to 82.02 pounds per woman in the immediate diagnosis and treatment group with an incremental cost of 27.60 pounds (95 per cent CI 22.04 pounds-33.17 pounds). However, the number of cases of CIN III detected increased by 69 per cent for the policy of immediate diagnosis and treatment. This led to an average cost effectiveness ration of 180.18 pounds for the immediate diagnosis and treatment group and 199.94 pounds per case of CIN III detected for the surveillance group, with a marginal cost effectiveness ratio of 148.22 pounds (95 per cent CI 94.01 pounds-309.33 pounds) for the immediate diagnosis and treatment group. CONCLUSION: Immediate diagnosis and treatment increases the total cost of managing mildly dyskaryotic smears but this increased cost is offset by a sharp increase in the number of cases of CIN III detected.

Community care for demented and non-demented elderly people: a comparison study of financial burden, service use, and unmet needs in family supporters.

OBJECTIVE: To measure and compare perceived financial burden, use of services, and perceived unmet service needs of supporters of demented and non-demented elderly people. DESIGN: Comparison study of age and sex matched demented and non-demented elderly people and their supporters. SETTING: 25 primary health care teams in Dundee. SUBJECTS: 114 community resident elderly (age over 65) people with dementia, 114 age and sex matched comparators, and the main informal supporter of each elderly person. MAIN OUTCOME MEASURES: Carers' perceptions of financial impact of looking after an old person, service use (from a list of locally available services), unmet service needs, and needs for three types of generic service (help with supervision, housework, or personal care). RESULTS: Financial impact was low, except for extra household expense in the dementia group. There was significantly greater use of mainstream domiciliary and day care services in the dementia group. Dementia was nevertheless associated with a high level of unmet need, mainly for more mainstream support and help with supervision of the elderly person. CONCLUSION: Supervisory care for demented elderly people should be further developed within an expanded domiciliary service to meet supporters needs.

Tailored written invitations for second round breast cancer screening: a randomised controlled trial.

OBJECTIVES: Firstly, to determine if attendance for second round mammography screening in those sent a tailored letter (that is, making reference to their screening history) is increased compared with those sent a standard letter; secondly, to investigate the acceptability of tailored letters. SETTING: North West Glasgow Breast Screening Centre. METHODS: A randomised controlled trial. RESULTS: Overall attendance was unrelated to whether the women were sent a tailored or standard letter; 60% of those sent the standard letter attended (922/1531) compared with 62% of those sent the tailored letter (956/1552) (chi 2 = 0.61, P = 0.4) (difference 2%; 95% confidence interval -2% to 5%). There were no significant differences in percentage attendance within each of the study subgroups: women who attended previously and received an all clear result, women who attended previously and received a false positive result, women who were invited previously and failed to attend, and women who were previously too young to be invited for screening. However, there was a statistically significant difference in percentage attendance between these four groups, independent of letter type (chi 2 = 510, P < 0.00001). Although women found the letters acceptable and understandable, they did not seem to pay close attention to the content. CONCLUSIONS: Tailoring invitation letters does not have a significant effect on uptake rates for breast screening and does not justify the additional workload required.

Moving towards a common understanding in maternity services.

There is a need to ensure that there is a common understanding of what is meant by the terminology surrounding the organisation and provision of maternity services. This is especially important with the development of purchaser/provider contracts in the National Health Service (NHS) in the UK. It is vitally important that terms specified in contracts are not ambiguous. It is also important that practitioners and researchers are working from a common base. Information on local definitions used in Scottish health boards was obtained through questionnaires sent to Heads of Midwifery Services in consultant units. The findings show that for some terms the definitions were fairly standard, but for others there were considerable differences in how the terms were interpreted. In light of these differences, and given the necessity for clearly defined terms within the new NHS, professionally agreed definitions were produced by the Royal College of Midwives. It is recommended that these definitions be adopted as standard by relevant individuals and groups.

Costing shared care.

Growing interest in shared health care schemes over the last decade has received additional impetus with the introduction of GP fund holding and the internal market in health care provision. Ken Buckingham and colleagues report on the relative costs of such a scheme for asthma in comparison with the costs of conventional outpatient care. Data was collected during a randomised controlled trial of shared or integrated care for patients with chronic asthma, who had been referred to a hospital outpatient clinic.

Adsorption of chloro-complexes of the first row transition elements by Dowex A-1.

A study has been made of the adsorption of chlorocomplexes of the first row transition metals by the chelating resin Dowex A-1, and possible mechanisms for adsorption have been reviewed. Relative adsorption follows the series Zn(II) > Co(II) = Fe(III) Cu(II) > Mn(II). Negligible adsorption occurred with Cr(III) and none with V(IV) and Ni(II). Maximum adsorption of Zn(II) occurred from 3M hydrochloric acid and for the other metals from 8M acid.