Continuing education: The 1998 survey of the Royal Australasian College of Dental Surgeons

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.Background: Continuing education (CE) is an essential professional activity. In the last decade, CE has been actively pursued by the medical profession in Australia and abroad. However, the uptake of CE in dentistry has been much slower and there is minimal Australian data on dental CE. Methods: To determine the level of CE activity, in 1998, postal questionnaires were sent to all fellows of the Royal Australasian College of Dental Surgeons. The responses were analysed. Results: There was a high reponse rate (90 per cent) but a moderate usable rate (54 per cent). The results show a biphasic distribution between high and low CE activity. The average amount of activity of those involved in CE was 116 hours per year, above the usually accepted minimum of 100 hours/year. Some groups, particularly members of the specialist divisions of oral and maxillofacial surgeons (215 hours) and periodontists (205 hours), have high levels of CE. However, approximately 25 per cent of college fellows reported little or no CE activity. The survey revealed that inactive fellows are more likely to be older and in general practice. Inactive fellows were also tardy in replying to the questionnaire. Conclusion: The high activity CE group needs to be recognised and encouraged to continue. Specific plans to help the low CE activity group should be developed. Although these findings relate directly to the Royal Australasian College of Dental Surgeons, they are presented as they have implications for the dental profession at large.P Sambrook, D Thomson, R Bastiaan and A Gos

A neural reward prediction error revealed by a meta-analysis of ERPs using great grand averages

Economic approaches to decision making assume that people attach values to prospective goods and act to maximize their obtained value. Neuroeconomics strives to observe these values directly in the brain. A widely used valuation term in formal learning and decision-making models is the reward prediction error: the value of an outcome relative to its expected value. An influential theory (Holroyd & Coles, 2002) claims that an electrophysiological component, feedback related negativity (FRN), codes a reward prediction error in the human brain. Such a component should be sensitive to both the prior likelihood of reward and its magnitude on receipt. A number of studies have found the FRN to be insensitive to reward magnitude, thus questioning the Holroyd and Coles account. However, because of marked inconsistencies in how the FRN is measured, a meaningful synthesis of this evidence is highly problematic. We conducted a meta-analysis of the FRN’s response to both reward magnitude and likelihood using a novel method in which published effect sizes were disregarded in favor of direct measurement of the published waveforms themselves, with these waveforms then averaged to produce “great grand averages.” Under this standardized measure, the meta-analysis revealed strong effects of magnitude and likelihood on the FRN, consistent with it encoding a reward prediction error. In addition, it revealed strong main effects of reward magnitude and likelihood across much of the waveform, indicating sensitivity to unsigned prediction errors or “salience.” The great grand average technique is proposed as a general method for meta-analysis of event-related potential (ERP). (PsycINFO Database Record (c) 2016 APA, all rights reserved

Principal components analysis of reward prediction errors in a reinforcement learning task

Models of reinforcement learning represent reward and punishment in terms of reward prediction errors (RPEs), quantitative signed terms describing the degree to which outcomes are better than expected (positive RPEs) or worse (negative RPEs). An electrophysiological component known as feedback related negativity (FRN) occurs at frontocentral sites 240-340 ms after feedback on whether a reward or punishment is obtained, and has been claimed to neurally encode an RPE. An outstanding question however, is whether the FRN is sensitive to the size of both positive RPEs and negative RPEs. Previous attempts to answer this question have examined the simple effects of RPE size for positive RPEs and negative RPEs separately. However, this methodology can be compromised by overlap from components coding for unsigned prediction error size, or "salience", which are sensitive to the absolute size of a prediction error but not its valence. In our study, positive and negative RPEs were parametrically modulated using both reward likelihood and magnitude, with principal components analysis used to separate out overlying components. This revealed a single RPE encoding component responsive to the size of positive RPEs, peaking at similar to 330ms, and occupying the delta frequency band. Other components responsive to unsigned prediction error size were shown, but no component sensitive to negative RPE size was found. (C) 2015 Elsevier Inc. All rights reserved

A national survey of the chemotherapy regimens used to treat small cell lung cancer (SCLC) in the United Kingdom

Many chemotherapy regimens are used for treating SCLC in the United Kingdom, but it is not known, in any detail, which regimens are used, by which specialists, for which types of patient. We conducted a survey among all medical and clinical oncologists, respiratory physicians and general physicians with respiratory interest in the United Kingdom to find out. The questionnaire asked for the number of SCLC patients treated annually; how many were given chemotherapy; the drugs, doses and schedules chosen according to prognostic group (as defined by the clinician); and the reasons for choice of regimen. 1214 questionnaires were sent out, and responses were received from 1070 (88%) clinicians; 266 (25%) of these treated SCLC with chemotherapy. Of 4674 patients given chemotherapy annually, 36% were given it by clinical oncologists, 30% by medical oncologists, 27% by respiratory physicians, and 7% by general physicians. In all, 34 regimens were reported with 151 different combinations of dose and schedule. In 2311 good prognosis patients, 23 regimens were used, the commonest being ACE (doxorubicin, cyclophosphamide, etoposide), ICbE (ifosfamide, carboplatin, etoposide), CAV (cyclophosphamide, doxorubicin, vincristine), CbE (carboplatin, etoposide), and PE (cisplatin, etoposide). In 1517 poor prognosis patients, 21 regimens were used, the commonest being CAV, EV (etoposide, vincristine), CbE, CAV alternating with PE, and oral etoposide. 452 patients were treated regardless of prognosis and for 219 no prognostic criteria were specified. The remaining 175 were given second-line chemotherapy or were given regimens chosen to avoid toxicity or because of intercurrent disease or other reasons. The main reasons affecting choice of regimen were routine local practice, patients' convenience, quality of life considerations, trial results and cost. The results show wide variation in routine practice and will be useful in reporting and planning clinical trials and in deciding on local treatment policies. © 2001 Cancer Research Campaign http://www.bjcancer.co

The Effect of Demineralization and Remineralization Cycles on the Bond Strength of Resin Composite to Enamel

Toothwear is a growing concern, particularly in young adults. Prevention strategies remain of utmost importance and may involve the use of remineralising agents. If restorative treatment is indicated, adhesive techniques are recommended. It is unknown whether remineralising agents affect adhesion. METHOD: 77 bovine incisors were subjected to simulated toothwear by erosion (0.3% citric acid) and abrasion (oscillating toothbrush). Samples were randomly arranged into 5 test and 2 control groups (n=11). Each test group had a remineralising agent applied. Subsequently, composite was bonded to each sample and subjected to shear bond testing. Shear bond strength, mode of failure and enamel surface changes were analysed. RESULTS: There was no statistically significant difference for bond strength between groups (p=0.262). Mode of failure was statistically significant between groups (p⟨0.0001). Qualitative analysis showed a surface layer on samples remineralised by calcium silicate and stannous fluoride. Both groups had more adhesive failures. CONCLUSION: Within the limitations of this study, it can be concluded that the remineralising agents tested do not affect shear bond strength though surface layers created on the enamel influence the mode of failure. These 'sacrificial' surface layers have the potential to protect the underlying enamel structure

Model-free and model-based reward prediction errors in EEG

Learning theorists posit two reinforcement learning systems: model-free and model-based. Model-based learning incorporates knowledge about structure and contingencies in the world to assign candidate actions with an expected value. Model-free learning is ignorant of the world’s structure; instead, actions hold a value based on prior reinforcement, with this value updated by expectancy violation in the form of a reward prediction error. Because they use such different learning mechanisms, it has been previously assumed that model-based and model-free learning are computationally dissociated in the brain. However, recent fMRI evidence suggests that the brain may compute reward prediction errors to both model-free and model-based estimates of value, signalling the possibility that these systems interact. Because of its poor temporal resolution, fMRI risks confounding reward prediction errors with other feedback-related neural activity. In the present study, EEG was used to show the presence of both model-based and model-free reward prediction errors and their place in a temporal sequence of events including state prediction errors and action value updates. This demonstration of model-based prediction errors questions a long-held assumption that model-free and model-based learning are dissociated in the brain

Is \gamma-ray emission from novae affected by interference effects in the 18F(p,\alpha)15O reaction?

The 18F(p,\alpha)15O reaction rate is crucial for constraining model predictions of the \gamma-ray observable radioisotope 18F produced in novae. The determination of this rate is challenging due to particular features of the level scheme of the compound nucleus, 19Ne, which result in interference effects potentially playing a significant role. The dominant uncertainty in this rate arises from interference between J\pi=3/2+ states near the proton threshold (Sp = 6.411 MeV) and a broad J\pi=3/2+ state at 665 keV above threshold. This unknown interference term results in up to a factor of 40 uncertainty in the astrophysical S-factor at nova temperatures. Here we report a new measurement of states in this energy region using the 19F(3He,t)19Ne reaction. In stark contrast with previous assumptions we find at least 3 resonances between the proton threshold and Ecm=50 keV, all with different angular distributions. None of these are consistent with J\pi= 3/2+ angular distributions. We find that the main uncertainty now arises from the unknown proton-width of the 48 keV resonance, not from possible interference effects. Hydrodynamic nova model calculations performed indicate that this unknown width affects 18F production by at least a factor of two in the model considered.Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev. Let