A closed loop cryogenic environment pressure regulating system

Nonlinear closed loop control system to regulate the pressure in a cryogenic environment is described. System employs four position contactor with two control bands to react to the signals. Diagrams of element transfer function and required equipment are included

Will a breast screening programme change the workload and referral practice of general practitioners?

This article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright © 1990 BMJ Publishing Group.STUDY OBJECTIVE--The aim of the study was to consider possible changes in the clinical activities of general practitioners whose patients are registered in a breast cancer screening programme. DESIGN--The study was a survey based on completion of forms recording breast consultations carried out by participating general practitioners during a four week period. SETTING--One of three intervention centres and one of three comparison centres in the national trial of early detection of breast cancer was selected. The intervention centre was in Guildford; the comparison centre in Stoke on Trent. PARTICIPANTS--The participants were general practitioners in the selected centres. In Guildford, 64 of 99 general practitioners approached took part (65%); in Stoke on Trent, 81 of 177 took part (46%). The proportion of male and female participants in the two centres was similar. Doctors in Stoke on Trent were older and worked in smaller practices than in Guildford. RESULTS--A comparison of workloads showed that in the screening centre there was less demand for doctor consultations from those in the screened age group, but those excluded from screening made more use of the general practitioners' services. A difference in referral practice was also apparent, with doctors in the screening centre referring more frequently for specialist advice. CONCLUSIONS--The evidence suggests that no significant change in the overall use of general practice resources can be expected with the introduction of national screening, but there may be greater pressure on assessment services

The influence on survival of delay in the presentation and treatment of symptomatic breast cancer

The aim of this study was to examine the possible influence on survival of delays prior to presentation and/or treatment among women with breast cancer. Duration of symptoms prior to hospital referral was recorded for 2964 women who presented with any stage of breast cancer to Guy's Hospital between 1975 and 1990. Median follow-up is 12.5 years. The impact of delay (defined as having symptoms for 12 or more weeks) on survival was measured from the date of diagnosis and from the date when the patient first noticed symptoms to control for lead-time bias. Thirty-two per cent (942/2964) of patients had symptoms for 12 or more weeks before their first hospital visit and 32% (302/942) of patients with delays of 12 or more weeks had locally advanced or metastatic disease, compared with only 10% (210/2022) of those with delays of less than 12 weeks (P< 0.0001). Survival measured both from the date of diagnosis (P< 0.001) and from the onset of the patient's symptoms (P= 0.003) was worse among women with longer delays. Ten years after the onset of symptoms, survival was 52% for women with delays less than 12 weeks and 47% for those with longer delays. At 20 years the survival rates were 34% and 24% respectively. Furthermore, patients with delays of 12–26 weeks had significantly worse survival rates than those with delays of less than 12 weeks. Multivariate analyses indicated that the adverse impact of delay in presentation on survival was attributable to an association between longer delays and more advanced stage. However, within individual stages, longer delay had no adverse impact on survival. Analyses based on ‘total delay’ (i.e. the interval between a patient first noticing symptoms and starting treatment) yielded very similar results in terms of survival to those based on delay to first hospital visit (delay in presentation). © 1999 Cancer Research Campaig