Avian cerebellar floccular fossa size is not a proxy for flying ability in birds

Extinct animal behavior has often been inferred from qualitative assessments of relative brain region size in fossil endocranial casts. For instance, flight capability in pterosaurs and early birds has been inferred from the relative size of the cerebellar flocculus, which in life protrudes from the lateral surface of the cerebellum. A primary role of the flocculus is to integrate sensory information about head rotation and translation to stabilize visual gaze via the vestibulo-occular reflex (VOR). Because gaze stabilization is a critical aspect of flight, some authors have suggested that the flocculus is enlarged in flying species. Whether this can be further extended to a floccular expansion in highly maneuverable flying species or floccular reduction in flightless species is unknown. Here, we used micro computed-tomography to reconstruct “virtual” endocranial casts of 60 extant bird species, to extract the same level of anatomical information offered by fossils. Volumes of the floccular fossa and entire brain cavity were measured and these values correlated with four indices of flying behavior. Although a weak positive relationship was found between floccular fossa size and brachial index, no significant relationship was found between floccular fossa size and any other flight mode classification. These findings could be the result of the bony endocranium inaccurately reflecting the size of the neural flocculus, but might also reflect the importance of the flocculus for all modes of locomotion in birds. We therefore conclude that the relative size of the flocculus of endocranial casts is an unreliable predictor of locomotor behavior in extinct birds, and probably also pterosaurs and non-avian dinosaurs

Finding black holes in numerical spacetimes

We have constructed a numerical code that finds black hole event horizons in an axisymmetric rotating spacetime. The spacetime is specified numerically by giving metric coefficients on a spatial grid for a series of time slices. The code solves the geodesic equation for light rays emitted from a suitable sample of points in the evolving spacetime. The algorithm for finding the event horizon employs the apparent horizon, which can form much later than the event horizon, to distinguish between light rays that escape to infinity and light rays that are captured. Simple geometries can be diagnosed on a workstation; more complicated cases are computationally intensive. However, the code is easily parallelized and has been efficiently run on the IBM SP-1 parallel machine. We have illustrated the use of the event horizon code on two cases. One is the head-on collision of two black holes that form from the collapse of collisionless matter, coalescing to a single Schwarzschild black hole. The other is the collapse of a rotating toroid to form a Kerr black hole. In this case the horizon initially appears with a toroidal topology. This is the first known example of this phenomenon

A randomised controlled trial of proactive telephone counselling on cold-called smokers' cessation rates

Objectives: Active telephone recruitment (‘cold calling’) can enrol almost 45 times more smokers to cessation services than media. However, the effectiveness of proactive telephone counselling with cold-called smokers from the broader community is unknown. This study examined whether proactive telephone counselling improved abstinence, quit attempts and reduced cigarette consumption among cold-called smokers. Methods: From 48014 randomly selected electronic telephone directory numbers, 3008 eligible smokers were identified and 1562 (51.9%) smokers recruited into the randomised controlled trial. Of these, 769 smokers were randomly allocated to proactive telephone counselling and 793 to the control (ie, mailed self-help) conditions. Six counselling calls were offered to intervention smokers willing to quit within a month and four to those not ready to quit. The 4-month, 7-month and 13-month follow-up interviews were completed by 1369 (87.6%), 1278 (81.8%) and 1245 (79.9%) participants, respectively. Results: Proactive telephone counselling participants were significantly more likely than controls to achieve 7-day point prevalence abstinence at 4 months (13.8% vs 9.6%, p=0.005) and 7 months (14.3% vs 11.0%, p=0.02) but not at 13 months. There was a significant impact of telephone counselling on prolonged abstinence at 4 months (3.4% vs 1.8%, p=0.02) and at 7 months (2.2% vs 0.9%, p=0.02). At 4 months post recruitment, telephone counselling participants were significantly more likely than controls to have made a quit attempt (48.6% vs 42.9%, p=0.01) and reduced cigarette consumption (16.9% vs 9.0%, p=0.0002). Conclusions: Proactive telephone counselling initially increased abstinence and quitting behaviours among cold-called smokers. Given its superior reach, quitlines should consider active telephone recruitment, provided relapse can be reduced

Formative student-authored question bank: perceptions, question quality and association with summative performance

Purpose of the study There are few studies on the value of authoring questions as a study method, the quality of the questions produced by students and student perceptions of student-authored question banks. Here we evaluate PeerWise, a widely used and free online resource that allows students to author, answer and discuss multiple-choice questions. Study design We introduced two undergraduate medical student cohorts to PeerWise (n=603). We looked at their patterns of PeerWise usage; identified associations between student engagement and summative exam performance; and used focus groups to assess student perceptions of the value of PeerWise for learning. We undertook item analysis to assess question difficulty and quality. Results Over two academic years, the two cohorts wrote 4671 questions, answered questions 606 658 times and posted 7735 comments. Question writing frequency correlated most strongly with summative performance (Spearman’s rank: 0.24, p=<0.001). Student focus groups found that: (1) students valued curriculum specificity; and (2) students were concerned about student-authored question quality. Only two questions of the 300 ’most-answered' questions analysed had an unacceptable discriminatory value (point-biserial correlation <0.2). Conclusions Item analysis suggested acceptable question quality despite student concerns. Quantitative and qualitative methods indicated that PeerWise is a valuable study tool

Effects of portion size on chronic energy intake

© 2007 Jeffery et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens