Biomedical subjects

Colin Bradley

Publications and source records attributed to Colin Bradley.

5 recordsLinked to original sources

PubMed2006

Hot-air optical turbulence generator for the testing of adaptive optics systems: principles and characterization.

A statistically repeatable, hot-air optical turbulence generator, based on the forced mixing of two air flows with different temperatures, is described. Characterization results show that it is possible to generate any turbulence strength up to CN2 Dh approximately 6 x 10(-10) m1/3, allowing a ratio of beam diameter to Fried's parameter as large as D/r0 approximately 25 for one crossing through the turbulator or D/r0 approximately 38 for two crossings. The outer scale (L0 approximately 133 +/- 60 mm) is found to be compatible with the turbulator mixing chamber size (170 mm), and the inner scale (l0 approximately 7.6 +/- 3.8 mm) is compatible with the values in the literature for the free atmosphere. The temporal power spectrum analysis of the centroid of the focused image shows good agreement with Kolmogorov's theory. Therefore the device can be used with confidence to emulate realistic turbulence in a controlled manner. A calibrated CN2 profile, both in layer altitude and strength, is necessary for the testing of off-axis adaptive optics correction (multiconjugate adaptive optics). Testing was done to calibrate the CN2 profile using the slope detection and ranging technique. The first results, with only one layer, show the validity of the approach and indicate that a multiple-pass scheme is viable with a few modifications of the current setup.

Journal Article↗

PubMed2006

Patients and health professionals' perspectives on the sociocultural influences on secondary cardiac behaviour: a qualitative study of the implications in policy and practice.

OBJECTIVES: To explore the similarities and differences between patients and health professionals' perspectives on the sociocultural influences on secondary cardiac behaviour, and the implications in policy and practice. METHODS: Qualitative study using grounded theory research. We used a linked, phased study to ascertain the factors which helped shape patients' views about their heart problems and how these influence secondary cardiac behaviour. We also explored health professionals' perspectives on patients' views and interpretations. A total of 70 participants, 56 patients and 14 health professionals, took part in individual and group interviews and focus groups. RESULTS: Patients seemed in control of their heart condition and communicated a sense of satisfaction in how they manage it. To interpret the sociocultural influences on secondary cardiac behaviour, patients used theirs and community knowledge of heart disease, personal constructions of cardiac illness, together with their individual belief systems, particularly relating to lay health beliefs. Individual interpretations were unique and contextual, but there were many common views which did not differ between patients. CONCLUSIONS: Patients and health professionals reported similar areas of influence but there were important differences in emphasis. Providers described the ambivalence between being positive about the future health of patients to boost their recovery process, and recognition that this positive outlook could be construed as a 'cure'.

Adult↗

PubMed2005

Reactions to treatment debriefing among the participants of a placebo controlled trial.

BACKGROUND: A significant proportion of trial participants respond to placebos for a variety of conditions. Despite the common conduct of these trials and the strong emphasis placed on informed consent, very little is known about informing participants about their individual treatment allocation at trial closure. This study aims to address this gap in the literature by exploring treatment beliefs and reactions to feedback about treatment allocation in the participants of a placebo-controlled randomized clinical trial (RCT). METHODS: Survey of trial participants using a semi-structured questionnaire including close and open-ended questions administered as telephone interviews and postal questionnaires. Trial participants were enrolled in a double-blind placebo-controlled RCT evaluating the effectiveness of corticosteroid for heel pain (ISRCTN36539116). The trial had closed and participants remained blind to treatment allocation. We assessed treatment expectations, the percentage of participants who wanted to be informed about their treatment allocation, their ability to guess and reactions to debriefing. RESULTS: Forty-six (73%) contactable participants responded to our survey. Forty-two were eligible (four participants with bilateral disease were excluded as they had received both treatments). Most (79%) participants did not have any expectations prior to receiving treatment, but many 'hoped' that something would help. Reasons for not having high expectations included the experimental nature of their care and possibility that they may get a placebo. Participants were hopeful because their pain was so severe and because they trusted the staff and services. Most (83%) wanted to be informed about their treatment allocation and study results. Over half (55%) said they could not guess which treatment they had been randomized to, and many of those who attempted a guess were incorrect. Reactions to treatment debriefing were generally positive, including in placebo responders. CONCLUSION: Our study suggests that most trial participants want to be informed about their treatment allocation and trial results. Further research is required to develop measure of hope and expectancy and to rigorously evaluate the effects of debriefing prospectively.

Adrenal Cortex Hormones↗

PubMed2004

The expression of aversion to medicines in general practice consultations.

Although the relevance of patients' views about medicines for their medicine taking behaviour is now well established, little is known about the ways in which these views are discussed in primary care consultations. In particular, many studies have demonstrated patients' aversion to medicines. This paper examines the form that aversion talk takes in the consultation and how doctors respond to patients' expression of aversion to medicines. It is based on a dataset of 35 case studies of general practice consultations in England. In interviews with researchers, aversion to medicines was expressed in 34 of the 35 cases. In consultations with doctors, aversion was expressed in 10 cases. The interactional dimension of aversion talk in consultations was analysed using Conversation Analysis, and two general patterns were identified. Aversion could be used as an interactional resource, or it could be a topic in its own right. If used as an interactional resource, no real discussion of patients' views of medicines took place. When aversion was a conversational topic in its own right, two situations were observed. Firstly, the doctor elicited patients' views directly. Secondly, patients initiated aversive talk using a range of indirect strategies to do so. Even when patients managed to express their aversion to medicines, doctors did not engage them in any real discussion of their views. A scheme of interpretation is suggested to explain these findings. In this scheme patients perceive medicines to be an extension of the doctor and to be beneficial. In this view it is right for doctors to prescribe medicines and for patients to take medicines. The results of this paper suggest that using aversion as an interactional resource might be the only safe way for patients to express their aversion without seeming to breach the social contract.

Adult↗

PubMed2003

Developing and using quantitative instruments for measuring doctor-patient communication about drugs.

Previous qualitative work has identified communication problems between doctors and patients in general practice consultations, particularly in relation to prescribing. This study aimed to develop quantitative measures to extend the research and provide instruments for both researchers and practitioners to use in monitoring communication and prescribing. Questionnaires were developed from existing instruments. When used with patients and doctors in a variety of general practices, the instruments appeared to be acceptable and had high response rates. While many consultations were satisfactory in terms of patients' expectations and their experiences with medicines, only 38% did not have any poor outcome. The results using quantitative instruments were similar to but less striking compared to our previous qualitative work. The research was developmental and findings suggest that unnecessary prescribing and problems in communication are more likely to lead to poor outcomes in terms of non-adherence and patients having barriers to using their medication.

Communication↗