Dopamine, affordance and active inference.

The role of dopamine in behaviour and decision-making is often cast in terms of reinforcement learning and optimal decision theory. Here, we present an alternative view that frames the physiology of dopamine in terms of Bayes-optimal behaviour. In this account, dopamine controls the precision or salience of (external or internal) cues that engender action. In other words, dopamine balances bottom-up sensory information and top-down prior beliefs when making hierarchical inferences (predictions) about cues that have affordance. In this paper, we focus on the consequences of changing tonic levels of dopamine firing using simulations of cued sequential movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) model of contextual uncertainty and set switching that can be quantified in terms of behavioural and electrophysiological responses. Furthermore, one can simulate dopaminergic lesions (by changing the precision of prediction errors) to produce pathological behaviours that are reminiscent of those seen in neurological disorders such as Parkinson's disease. We use these simulations to demonstrate how a single functional role for dopamine at the synaptic level can manifest in different ways at the behavioural level

613 cases of splenic rupture without risk factors or previously diagnosed disease: a systematic review

Background Rupture of the spleen in the absence of trauma or previously diagnosed disease is largely ignored in the emergency literature and is often not documented as such in journals from other fields. We have conducted a systematic review of the literature to highlight the surprisingly frequent occurrence of this phenomenon and to document the diversity of diseases that can present in this fashion. Methods Systematic review of English and French language publications catalogued in Pubmed, Embase and CINAHL between 1950 and 2011. Results We found 613 cases of splenic rupture meeting the criteria above, 327 of which occurred as the presenting complaint of an underlying disease and 112 of which occurred following a medical procedure. Rupture appeared to occur spontaneously in histologically normal (but not necessarily normal size) spleens in 35 cases and after minor trauma in 23 cases. Medications were implicated in 47 cases, a splenic or adjacent anatomical abnormality in 31 cases and pregnancy or its complications in 38 cases. The most common associated diseases were infectious (n = 143), haematologic (n = 84) and non-haematologic neoplasms (n = 48). Amyloidosis (n = 24), internal trauma such as cough or vomiting (n = 17) and rheumatologic diseases (n = 10) are less frequently reported. Colonoscopy (n = 87) was the procedure reported most frequently as a cause of rupture. The anatomic abnormalities associated with rupture include splenic cysts (n = 6), infarction (n = 6) and hamartomata (n = 5). Medications associated with rupture include anticoagulants (n = 21), thrombolytics (n = 13) and recombinant G-CSF (n = 10). Other causes or associations reported very infrequently include other endoscopy, pulmonary, cardiac or abdominal surgery, hysterectomy, peliosis, empyema, remote pancreato-renal transplant, thrombosed splenic vein, hemangiomata, pancreatic pseudocysts, splenic artery aneurysm, cholesterol embolism, splenic granuloma, congenital diaphragmatic hernia, rib exostosis, pancreatitis, Gaucher's disease, Wilson's disease, pheochromocytoma, afibrinogenemia and ruptured ectopic pregnancy. Conclusions Emergency physicians should be attuned to the fact that rupture of the spleen can occur in the absence of major trauma or previously diagnosed splenic disease. The occurrence of such a rupture is likely to be the manifesting complaint of an underlying disease. Furthermore, colonoscopy should be more widely documented as a cause of splenic rupture

Exploring teacher roles and pupil outcomes in technology-rich early literacy learning

The present study focused on the involvement of Dutch kindergarten teachers in curriculum (design and) implementation of PictoPal activities in three different roles: executor-only, re-designer, and co-designer. PictoPal refers to ICT-rich on- and off-computer activities for early literacy. In the executor-only role, teachers were not involved in design; they implemented ready-made PictoPal activities in their classes. The re-designer and co-designer roles involved teams of teachers in a purposeful act of adjusting, respectively designing and implementing PictoPal. The aim of this study was to understand how teacher roles influence implementation of PictoPal and pupil learning outcomes. Case studies were used to examine each teacher role, and a cross-case analysis was undertaken to compare teacher roles with each other on a common set of measures: teacher perceptions about their role, curriculum practicality, and co-ownership; integration of on- and off-computer activities; and pupil learning. The data was gathered using interviews, checklists, and pre- and post-tests. The findings of this study showed that each teacher role (executor-only, re-designer, and co-designer) contributes significantly to the effectiveness of ICT-rich early literacy learning activities. Significant differences in integration of the on- and off-computer activities were found between the three teacher roles. Teachers as co-designers showed highest extent of integration. Across teacher roles, pupil learning outcomes were not straightforwardly related to the extent of integration. However, teachers as co-designers felt a sense of co-ownership towards PictoPal, which yielded high degrees of integration and willingness to extend implementation of PictoPal beyond the research context. Based on this study, it can be recommended that schools wishing to support early literacy development in kindergarten could responsibly choose to do so by engaging their teachers in collaborative design of ICT-rich activitie

Penney, G., May 26, 1982, Part 2. David Taylor interviewing George Penney regarding boatbuilding.

Part 2 of David Taylor's May 26, 1982 interview with George Penney regarding boatbuilding. Mr. Penney discusses the future of boatbuilding in his area

The political life of rising acid mine water

The discovery of gold on the Witwatersrand in 1886 that gave rise to the exploitation of the world’s largest gold reserves inaugurated new associations of air and earth, science and politics, humans and nonhumans. Very rapidly, these were organised into two apparently distinct realms—an aboveground world of capital, commerce, culture and politics and a belowground world of labour, minerals, rocks and science. Yet the two realms were deeply interconnected, and the threshold between them was always, literally and figuratively, in danger of collapsing. In this paper, I explore the use of legislation and cartography to stabilise this section and keep the two realms apart, and the aesthetic practices that portrayed their interrelatedness. I then chronicle the incursion of acid mine water, a geological by-product of mining operations, from the mining voids into the above-ground world of human affairs. This not only made the invisible processes of its commodification visible but also became a proposition around which new forms of political life have been assembled