35,543 research outputs found

    Improving the quality of consent to randomised controlled trials by using continuous consent and clinician training in the consent process

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    Objectives: To assess whether continuous consent, a process whereby information is given to research participants at different stages in a trial, plus clinician training in that process was effective when used by clinicians gaining consent to the TOBY trial. The TOBY trial is a randomised controlled trial investigating the use of whole body cooling for neonates with evidence of perinatal asphyxia. Obtaining valid informed consent for TOBY is difficult; as such, it is a good test of the effectiveness of continuous consent. Methods: Semi-structured interviews were conducted with 30 sets of parents who gave consent to TOBY and with 10 clinicians who sought it using the continuous consent process. Analysis focused on the validity of parental consent based upon the consent components of competence, information, understanding and voluntariness. Results: 19/27 (70%) couples had no significant problems with consent validity at the point of signature. Problems lay mainly with the parents’ competence and understanding. Mothers particularly had competence problems in the early stages of consent. The understanding problems were primarily to do with side effects. Problems in both areas (competence and understanding) reduced markedly, particularly for mothers, in the post signature phase when further discussion took place. Randomisation was generally understood but unpopular. Clinicians did not always give information in stages during the short period of time available before parents gave consent. However, most clinicians were able to give follow up information. Discussion: The consent validity compares favourably with similar trials examined in a comparable study (the Euricon study). Conclusion: Researchers should consider adopting elements of the continuous consent process and clinician training in RCTs, particularly where they have concerns about the quality of consent they are likely to obtain using a conventional process.</p

    Should desperate volunteers be included in randomised controlled trials?

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    Randomised controlled trials (RCTs) sometimes recruit participants who are desperate to receive the experimental treatment. Some claim this practice is unethical for at least three reasons. The first is that the notion of equipoise, which is often used as a justification for running a RCT, is subjective and value-based. Desperate volunteers are clearly not in equipoise and it is their values that should take precedence. The second is that clinicians who enter patients onto trials are disavowing their therapeutic obligation to deliver the best treatment to patients; they are following trial protocols rather than delivering individualised care. Research is not treatment; its ethical justification is different. Consent is crucial. This leads to the third reason: desperate volunteers do not give a proper consent; they are, in effect, coerced. We begin our reply by advocating a notion of equipoise based on, first, expert knowledge and, second, widely shared values. Where such collective, expert equipoise exists there is a prima facie case for a RCT. Next we argue that trial entry does not involve clinicians’ disavowing their therapeutic obligation; individualised care based on whims and fancies is not in patients’ best interest. Finally, we argue that where equipoise exists it is acceptable to limit access to experimental agents. In the cases desperate volunteers are not coerced because their desperation does not translate into a right to receive what they desire. </p

    From 2D Integrable Systems to Self-Dual Gravity

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    We explain how to construct solutions to the self-dual Einstein vacuum equations from solutions of various two-dimensional integrable systems by exploiting the fact that the Lax formulations of both systems can be embedded in that of the self-dual Yang--Mills equations. We illustrate this by constructing explicit self-dual vacuum metrics on R2×Σ\R^2\times \Sigma, where Σ\Sigma is a homogeneous space for a real subgroup of SL(2, \C) associated with the two-dimensional system.Comment: 9 pages, LaTex, no figure

    What to do about poor clinical performance in clinical trials

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    The performance of individual clinicians is being monitored as never before. Su Mason and colleagues discuss the implications of this for clinical trials and recommend what should happen if during a trial the performance of one clinician or one centre is identified as being particularly poor. Tom Treasure, a surgeon, wants the monitoring to be done fairly and to take account of the complexities of clinical practice; and Heather Goodare, a patient, wants to be told when things go wrong. The Department of Health in England has issued guidelines for research governance stating that healthcare organisations remain responsible for the quality of all aspects of patients' care whether or not some aspects of the care are part of a research study.1 We discuss how this obligation can be met in multicentre trials, given that data on the performance of clinicians are held by the trial management team, not by the host organisation

    Stryker Osteonics: Prosthetic Knee Joint

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    We examine, within a simple bearing model of a knee joint that only consideres pure sliding, the effect of the presence of a small vertical hole in the load area on the fluid film properties. The calculations indicate that fluid is entrapped in such a hole, which, for constant load, causes a smaller minimal film separation of the two surfaces. This will lower the horizontal friction, but may also bring about surface contact in high load situations

    Strong absorption and selective thermal emission from a mid-infrared metamaterial

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    We demonstrate thin-film metamaterials with resonances in the mid-infrared wavelength range. Our structures are numerically modeled and experimentally characterized by reflection and angularly-resolved thermal emission spectroscopy. We demonstrate strong and controllable absorption resonances across the mid-infrared wavelength range. In addition, the polarized thermal emission from these samples is shown to be highly selective and largely independent of emission angles from normal to 45 degrees. Experimental results are compared to numerical models with excellent agreement. Such structures hold promise for large-area, low-cost metamaterial coatings for control of gray- or black-body thermal signatures, as well as for possible mid-IR sensing applications.Comment: The following article has been submitted to Appl. Phys. Lett. After it is published, it will be found at http://apl.aip.org/. 14 pages including 4 figure page

    Symmetry breaking by quantum coherence in single electron attachment

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    Quantum coherence-induced effects in atomic and molecular systems are the basis of several proposals for laser-based control of chemical reactions. So far, these rely on coherent photon beams inducing coherent reaction pathways that may interfere with one another, in order to achieve the desired outcome. This concept has been successfully exploited for removing the inversion symmetry in the dissociation of homonuclear diatomic molecules, but it remains to be seen if such quantum coherent effects can also be generated by interaction of incoherent electrons with such molecules. Here we show that resonant electron attachment to H2 and the subsequent dissociation into H (n=2) + H− is asymmetric about the inter-nuclear axis, while the asymmetry in D2 is far less pronounced. We explain this observation as due to attachment of a single electron resulting in a coherent superposition of two resonances of opposite parity. In addition to exemplifying a new quantum coherent process, our observation of coherent quantum dynamics involves the active participation of all three electrons and two nuclei, which could provide new tools for studying electron correlations as a means to control chemical processes and demonstrates the role of coherent effects in electron induced chemistry
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