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David Richards

Publications and source records attributed to David Richards.

14 recordsLinked to original sources
PubMed2004

Near-field microscopy and lithography of light-emitting polymers.

We describe the application of scanning near-field optical microscopy (SNOM) to the study of the photophysical and self-organization properties of thin films of blends of conjugated polymers, and also to the lateral nanoscale patterning of conjugated-polymer structures. Such thin-film plastic semiconductor nanostructures offer significant potential for use in opto-electronic devices. The implementation of SNOM we employ is the most established form in which a probe with a sub-wavelength aperture is scanned in close proximity to the sample surface. We consider the nature of the near-field optical distribution, which decays within the first ca. 100 nm of these semiconductor materials, and address the identification of topographic artefacts in near-field optical images. While the topographic information obtained simultaneously with optical data in any SNOM experiment enables an easy comparison with the higher-resolution tapping-mode atomic force microscopy, the spectroscopic contrast provided by fluorescence SNOM gives an unambiguous chemical identification of the different phases in a conjugated-polymer blend. Both fluorescence and photoconductivity SNOM indicate that intermixing of constituent polymers in a blend, or nanoscale phase separation, is responsible for the high efficiency of devices employing these materials as their active layer. We also demonstrate a scheme for nano-optical lithography with SNOM of conjugated-polymer structures, which has been employed successfully for the fabrication of poly(-phenylene vinylene) nanostructures with 160 nm feature sizes.

Journal Article↗
PubMed2004

Resonant excitation of tip plasmons for tip-enhanced Raman SNOM.

The conditions necessary for the optimisation of tip-enhanced scanning near-field optical microscopy have been determined. The Raman scattering efficiency can be enormously increased by enhancements in the local field amplitude, such as that which can occur in the vicinity of a metallic nanostructure. The field enhancement in the vicinity of a silver tip is investigated theoretically here using the finite difference time domain method. Field enhancements from electron oscillations on the tip are shown to display strong maxima at resonant illumination wavelengths and the nature of these enhancements at the substrate surface beneath the tip, both on and off resonance, has been calculated. The enhancement of the Raman signal on the surface decreases exponentially as the tip-substrate separation is increased and a peak Raman enhancement of 10(7) is theoretically achievable at a tip-surface separation of 2 nm. The resolution is also strongly related to the distance between the tip and the substrate surface narrowing to <7 nm, significantly smaller than the radius of curvature of the end of the tip.

Journal Article↗
PubMed2003

Near-field microscopy: throwing light on the nanoworld.

Optical microscopy with nanoscale resolution, beyond that which is possible with conventional diffraction-limited microscopy, may be achieved by scanning a nanoantenna in close proximity to a sample surface. This review will first aim to provide an overview of the basic principles of this technique of scanning near-field optical microscopy (SNOM), before moving on to consider the most widely implemented form of this microscopy, in which the sample is illuminated through a small aperture held less than 10 nm from the sample surface for optical imaging with a resolution of ca. 50 nm. As an example of the application of this microscopy, the results of SNOM measurements of light-emitting polymer nanostructures are presented. In particular, SNOM enables the unambiguous identification of the different phases present in the nanostructures, through the local analysis of the fluorescence from the polymers. The exciting new possibilities for high-resolution optical microscopy and spectroscopy promised by apertureless SNOM techniques are also considered. Apertureless SNOM may involve local scattering of light from a sample surface by a tip, local enhancement of an optical signal by a metal tip, or the use of a fluorescent molecule or nanoparticle attached to a tip as a local optical probe of a surface. These new optical nanoprobes offer the promise of optical microscopy with true nanometre spatial resolution.

Fiber Optic Technology↗
PubMed2003

Critical realism: a way forward for evaluation research in nursing?

BACKGROUND: Critical realism is a relatively new philosophical perspective that combines a realist ontology with a relativist epistemology in subscribing to a form of "robust" relativism. The potential benefits of adopting a critical realist approach are considered in two areas of evaluation research: theory-driven programme evaluation and policy evaluation. AIM: The aim of the paper is to identify the main features of critical realism and explore its potential as a philosophical framework in the field of evaluation research. CONCLUSION: We argue that critical realism provides a coherent framework for evaluation research that is based on the understanding of causal mechanisms. This is particularly important for frontline services seeking to use evidence-based interventions, as interventions need to be properly understood if they are to be used effectively in the context of clinical practice. Critical realism can also add depth to policy analysis. However, there is a potential for critical realists to drift beyond the boundary that separates scientific knowledge from speculative theory when making recommendations about the best course of action to follow.

Evaluation Studies as Topic↗
PubMed2003

Agoraphobia: nurse therapist-facilitated self-help manual.

BACKGROUND: Agoraphobia is a common and disabling mental health disorder. Substantial evidence supports the use of cognitive behaviour therapy (CBT), in particular the intervention termed exposure therapy, as the treatment of choice. However, although the evidence base for cognitive-behaviour therapy is extensive, the service delivery evidence base is poor, and alternative ways of delivering therapy are required if mental health services are to achieve standards set out by the National Service Framework in the United Kingdom. AIM: The study had two aims: (1) to develop a self-help manual, which could be facilitated by a nurse trained in CBT, for clients suffering from agoraphobia and (2) to pilot the self-help manual and evaluate its effectiveness. METHOD: The self-help manual was piloted with experienced nurses trained in CBT on three clinical sites for 10 weekly sessions of 30 minutes duration. A range of clinical outcome measures was administered by an independent assessor before and after treatment and at 1-month follow-up. RESULTS: A total of 18 clients completed treatment and results showed improvement on all clinical measures; improvement was maintained at 1-month follow-up. Importantly, 89% of clients were clinically significantly improved at post-treatment assessment. Clients were satisfied with their treatment and the self-help manual, and therapists found facilitated self-help an acceptable way to deliver treatment. CONCLUSION: Nurses can deliver effective support to patients using a self-help manual for agoraphobia. Although the results are promising, further work is required with larger numbers, longer follow-up and economic evaluation under controlled conditions. The work could also be adapted to different psychological conditions. Variation in the amount of specialist educational training is necessary to determine how many nurses are needed to support patients using self-help.

Adolescent↗
PubMed2003

Effectiveness of nursing interventions in people with personality disorders.

BACKGROUND: Nurses usually provide care for people with personality disorders on a day-to-day basis. Consequently, it is important to establish how effective nursing interventions are for those with personality disorders, both in terms of general management and more specific therapeutic approaches. These are also issues of current political and professional debate. The crucial question, however, for planners, providers and commissioners of services is, What research evidence is there about effectiveness? There is also a need to determine what further research is necessary to evaluate programmes for managing or modifying behaviours. AIM: The aim of this paper is to report on a systematic review of the literature on the effectiveness of nursing interventions in people with personality disorders, whether delivered by nurses alone or in combination with other health care professionals. METHOD: The review was conducted according to the United Kingdom National Health Service Centre for Reviews and Dissemination guidelines. Literature was identified from electronic database searching, footnote chasing, hand searching of journals and contact with authors of studies. Narrative synthesis was undertaken in relation to study design, participants, and type of intervention. FINDINGS: Eighteen separate studies were included in the review: four randomized controlled trials, four non-randomized controlled trials, seven before-and-after studies and three case studies. CONCLUSIONS: There is a weak evidence-base for what constitutes effective nursing intervention with people with personality disorders. There is stronger evidence from mixed disciplines intervention studies than from nursing only intervention studies. Studies of interventions based on psychological approaches show greater improvements in outcomes than nursing management studies.

Adolescent↗
PubMed2003

PHASE: a randomised, controlled trial of supervised self-help cognitive behavioural therapy in primary care.

BACKGROUND: Common mental health problems account for up to 40% of all general practitioner (GP) consultations. Patients have limited access to evidence-based psychological therapies. Cognitive behavioural therapy self-help strategies offer one potential solution. AIM: To determine differences in clinical outcome, patient satisfaction and costs, between a cognitive behavioural-based self-help package facilitated by practice nurses compared to ordinary care by GPs for mild to moderate anxiety and depression. DESIGN OF STUDY: Randomised controlled trial. SETTING: Seventeen primary healthcare teams. METHOD: Patients presenting to their GP with mild to moderate anxiety and/or depression were recruited to the study and randomised to receive either a self-help intervention facilitated by practice nurses or ordinary care. The self-help intervention consisted of up to three appointments: two 1 week apart and a third 3 months later. There were no restrictions on ordinary care. RESULTS: Intention-to-treat analysis showed that patients treated with practice nurse-supported cognitive behavioural therapy self-help attained similar clinical outcomes for similar costs and were more satisfied than patients treated by GPs with ordinary care. On-treatment analysis showed patients receiving the facilitated cognitive behavioural therapy self-help were more likely to be below clinical threshold at 1 month compared to the ordinary care group (odds ratio [OR] = 3.65, 95% confidence interval [CI] = 1.87 to 4.37). This difference was less well marked at 3 months (OR = 1.36, 95% CI = 0.52 to 3.56). CONCLUSION: Facilitated cognitive behavioural self-help may provide a short-term cost-effective clinical benefit for patients with mild to moderate anxiety and depression. This has the potential to help primary care provide a choice of effective psychological as well as pharmacological treatments for mental health problems.

Adolescent↗
PubMed2002

Treatment planning in the 21st century: what's new?

Many variables affect treatment planning, and it is important for clinicians to consider why they plan certain procedures for patient care. New materials, technologies, and products are constantly being introduced and affect decision making in dentistry. In addition, patients are more informed, have higher esthetic concerns, and want a greater stake in treatment planning decisions than ever before. How dentists treatment plan needs to reflect the many influences on final treatment outcome. The purpose of this paper is to outline how treatment planning has changed in dentistry with the goal of providing the general dentist updated information to develop a cohesive treatment plan.

Dental Materials↗
PubMed2002

Considerations for anterior implant esthetics.

There are several factors to consider when restoring failing dentition in the anterior region. While a tooth can be replaced with an implant, achieving an esthetic result is challenging. The dental team must evaluate numerous criteria to define the optimal treatment plan. Among the considerations are whether to extract the tooth and perform immediate implant replacement or to perform a ridge preservation procedure. This article presents diagnostic determinants to help decide the most appropriate course of therapy to achieve functional and esthetic results.

Alveolar Bone Loss↗
PubMedDate not supplied

Comparison of double-plate Molteno and Ahmed glaucoma valve in patients with advanced uncontrolled glaucoma.

BACKGROUND AND OBJECTIVE: To compare double-plate Molteno (DPM) with the Ahmed glaucoma valve (AGV) in the treatment of eyes with complicated glaucoma. PATIENTS AND METHODS: This matched, retrospective, case-control study was based on diagnosis, number of previous operations, and age. There were 30 patients in each group and only patients with a minimum of 6 months follow up were included. Double-plate Molteno or Ahmed glaucoma valve insertion was performed on each patient to control intractable glaucoma. Success was defined as IOP <22 mm Hg and >4 mm Hg on the last two visits, a decrease of no more than 2 lines in the visual acuity, and no additional surgical intervention to control IOP. RESULTS: The Kaplan-Meier estimated probability of success at 12 and 24 months was 73% and 56% with DPM and 60% and 50% for AGV (P = 0.72). Mean IOP measured 13.36 +/- 5.2 mm Hg following DPM and 16.7 +/- 5.6 mm Hg following AGV at 12 months (P = 0.026) and 13.3 +/- 5.1 mm Hg with DPM and 19 +/- 5.8 mm Hg with AGV at 24 months (P = 0.009). Of the patients involved in the study, 83.5% exhibited hypertensive phase (HP) of AGV vs 43.5% of DPM (P = 0.04). AGV had a tendency to fail earlier (5 months +/- 7 following AGV vs 13 months +/- 13 following DPM, P = 0.07, t-test). Patients with either a second valve insertion or valve removal were 7/30 of AGV vs 1/30 in DPM (P = 0.05). Stent removal was needed by 10/30 DPM and 8/30 AGV had needling/5-FU. CONCLUSIONS: The percentage of patients free from failure was similar between the two groups at 36 months. DPM is associated with lower mean IOP in the long term compared to AGV.

Adolescent↗