Non-adjacent dependency learning in infancy, and its link to language development

To acquire language, infants must learn how to identify words and linguistic structure in speech. Statistical learning has been suggested to assist both of these tasks. However, infants’ capacity to use statistics to discover words and structure together remains unclear. Further, it is not yet known how infants’ statistical learning ability relates to their language development. We trained 17-month-old infants on an artificial language comprising non-adjacent dependencies, and examined their looking times on tasks assessing sensitivity to words and structure using an eye-tracked head-turn-preference paradigm. We measured infants’ vocabulary size using a Communicative Development Inventory (CDI) concurrently and at 19, 21, 24, 25, 27, and 30 months to relate performance to language development. Infants could segment the words from speech, demonstrated by a significant difference in looking times to words versus part-words. Infants’ segmentation performance was significantly related to their vocabulary size (receptive and expressive) both currently, and over time (receptive until 24 months, expressive until 30 months), but was not related to the rate of vocabulary growth. The data also suggest infants may have developed sensitivity to generalised structure, indicating similar statistical learning mechanisms may contribute to the discovery of words and structure in speech, but this was not related to vocabulary size

A Clathrin Independent Macropinocytosis-Like Entry Mechanism Used by Bluetongue Virus-1 during Infection of BHK Cells

Acid dependent infection of Hela and Vero cells by BTV-10 occurs from within early-endosomes following virus uptake by clathrin-mediated endocytosis (Forzan et al., 2007: J Virol 81: 4819–4827). Here we report that BTV-1 infection of BHK cells is also dependent on a low endosomal pH; however, virus entry and infection were not inhibited by dominant-negative mutants of Eps15, AP180 or the ‘aa’ splice variant of dynamin-2, which were shown to inhibit clathrin-mediated endocytosis. In addition, infection was not inhibited by depletion of cellular cholesterol, which suggests that virus entry is not mediated by a lipid-raft dependent process such as caveolae-mediated endocytosis. Although virus entry and infection were not inhibited by the dominant-negative dynamin-2 mutant, entry was inhibited by the general dynamin inhibitor, dynasore, indicating that virus entry is dynamin dependent. During entry, BTV-1 co-localised with LAMP-1 but not with transferrin, suggesting that virus is delivered to late-endosomal compartments without first passing through early-endosomes. BTV-1 entry and infection were inhibited by EIPA and cytochalasin-D, known macropinocytosis inhibitors, and during entry virus co-localised with dextran, a known marker for macropinocytosis/fluid-phase uptake. Our results extend earlier observations with BTV-10, and show that BTV-1 can infect BHK cells via an entry mechanism that is clathrin and cholesterol-independent, but requires dynamin, and shares certain characteristics in common with macropinocytosis

The convergence of virtual reality and social networks: threats to privacy and autonomy

The rapid evolution of information, communication and entertainment technologies will transform the lives of citizens and ultimately transform society. This paper focuses on ethical issues associated with the likely convergence of virtual realities (VR) and social networks (SNs), hereafter VRSNs. We examine a scenario in which a significant segment of the world’s population has a presence in a VRSN. Given the pace of technological development and the popularity of these new forms of social interaction, this scenario is plausible. However, it brings with it ethical problems. Two central ethical issues are addressed: those of privacy and those of autonomy. VRSNs pose threats to both privacy and autonomy. The threats to privacy can be broadly categorized as threats to informational privacy, threats to physical privacy, and threats to associational privacy. Each of these threats is further subdivided. The threats to autonomy can be broadly categorized as threats to freedom, to knowledge and to authenticity. Again, these three threats are divided into subcategories. Having categorized the main threats posed by VRSNs, a number of recommendations are provided so that policy-makers, developers, and users can make the best possible use of VRSNs

Fatality after deliberate ingestion of sustained-release ibuprofen: a case report

INTRODUCTION: Ibuprofen is a nonsteroidal anti-inflammatory drug available over the counter and on prescription for the management of pain and inflammation. Severe toxicity is rare following deliberate self-poisoning with ibuprofen, and patients are usually either asymptomatic or develop only mild gastrointestinal toxicity. Although there have been nine other reported fatalities, co-existent factors have probably contributed to all of these deaths. We report here a fatality from isolated toxicity following self-poisoning with sustained-release ibuprofen. CASE REPORT: A 26-year-old female presented after deliberate ingestion of up to 105 g sustained-release ibuprofen, with a reduced level of consciousness, severe metabolic acidosis and haemodynamic compromise. Despite intensive supportive management, gut decontamination with multidose activated charcoal and correction of the metabolic acidosis with sodium bicarbonate and haemofiltration, the patient did not survive. The ibuprofen concentration ante mortem on presentation in peripheral blood was 760 mg/l and the concentrations post mortem were 518 mg/l in peripheral blood, 74 mg/kg in liver extract and 116 mg/l in the gastric contents. DISCUSSION: Most patients with ibuprofen poisoning are either asymptomatic or have mild gastrointestinal symptoms; severe poisoning with ibuprofen is rare. We report the first death related to isolated sustained-release ibuprofen poisoning

The changing role of sound symbolism for small versus large vocabularies

Natural language contains many examples of sound-symbolism, where the form of the word carries information about its meaning. Such systematicity is more prevalent in the words children acquire first, but arbitrariness dominates during later vocabulary development. Furthermore, systematicity appears to promote learning category distinctions, which may become more important as the vocabulary grows. In this study, we tested the relative costs and benefits of sound-symbolism for word learning as vocabulary size varies. Participants learned form meaning mappings for words which were either congruent or incongruent with regard to sound-symbolic relations. For the smaller vocabulary, sound-symbolism facilitated learning individual words, whereas for larger vocabularies sound-symbolism supported learning category distinctions. The changing properties of form-meaning mappings according to vocabulary size may reflect the different ways in which language is learned at different stages of development

Running virtual reactions: A reaction predictor app for teaching organic chemistry

Background: Students are often daunted by the process of learning the functional groups (FG’s) and functional group interconversions (FGI’s) in undergraduate organic chemistry courses.1-3 Problems arise when students attempt to rote learn, rather than understand and predict reactions.4 Owing to the portability and increasing proliferation of mobile platforms (i.e. smartphones and tablet devices), a unique opportunity exists for teaching organic chemistry, via active-learning methods, which increase the meaningfulness and retention of course material. In particular, the use of reaction prediction applications has the potential to encourage students to use problem-based, self-directed and collaborative learning methods. While reaction prediction programs have been developed for desktop computers, research in the field has stagnated, and there are no predictors available for mobile platforms.5 Aims: to develop a reaction predictor app with mobile and desktop support. The app will let students sketch any chemical structure, then add single or multiple reagents to the structure, to predict the reaction product(s). The purpose of the app is to increase student understanding and retention of FGI’s without using rote-learning techniques. We’re also interested to see if students use the app as a game, i.e. for enjoyment, particularly when challenging other students in the ‘head-to-head’ mode. Design and methods: we will code the predictor using JavaScript. Rules for FGI’s will be defined using SMIRKS notation (a derivative of SMILES used for reaction transforms). All reagents in a specified reaction will be compared against the rule database, and the likely products displayed to the user as images. Feedback analytics tools will let the app automatically sample data from all users: our focus will be on app usage duration and frequency. Touch/click and multiplayer analytics will be provided using heat maps, and real-time activity streaming. In-app feedback screens will collect student self-evaluation, and enjoyment/satisfaction trends. Traditional surveying methods will be used to collect data that the app gathered insufficiently. Finally, student results (within application problem sets, and within subject assessments) will be compared with student self-reported data, and their duration and frequency of application use. Anticipated results: the reaction predictor will be built as a hybrid web-app, working on iOS, Android and Internet-connected desktops. Users can input structures (to be used as reagents or target molecules) by sketching them, or by taking photos of structures using their device’s inbuilt camera. Problem sets will be included, wherein users are required to virtually synthesise a target molecule, from a starting material, in a specified number of steps. A multi-user mode will allow students to collaborate in building target molecules, or to compete for the same purpose (by time, or by number-of-steps). We will be using a large first year and smaller second-year cohort organic chemistry subject at UOW as the sample frame, and beta testing. All students should report improved understanding of FGI’s within each problem set, and overall in the subject, which should be reflected in the assessment of learning outcomes. Anticipated conclusion: a reaction prediction application was successfully developed for multiple platforms, and improved understanding of FGI’s, making it ready for wider testing and distribution among undergraduate students and other institutions

The Nature of Angular Momentum Transport in Radiative Self-Gravitating Protostellar Discs

Semi-analytic models of self-gravitating discs often approximate the angular momentum transport generated by the gravitational instability using the phenomenology of viscosity. This allows the employment of the standard viscous evolution equations, and gives promising results. It is, however, still not clear when such an approximation is appropriate. This paper tests this approximation using high resolution 3D smoothed particle hydrodynamics (SPH) simulations of self-gravitating protostellar discs with radiative transfer. The nature of angular momentum transport associated with the gravitational instability is characterised as a function of both the stellar mass and the disc-to-star mass ratio. The effective viscosity is calculated from the Reynolds and gravitational stresses in the disc. This is then compared to what would be expected if the effective viscosity were determined by assuming local thermodynamic equilibrium or, equivalently, that the local dissipation rate matches the local cooling rate. In general, all the discs considered here settle into a self-regulated state where the heating generated by the gravitational instability is modulated by the local radiative cooling. It is found that low-mass discs can indeed be represented by a local "alpha-parametrisation", provided that the disc aspect ratio is small (H/R < 0.1) which is generally the case when the disc-to-star mass ratio q <0.5. However, this result does not extend to discs with masses approaching that of the central object. These are subject to transient burst events and global wave transport, and the effective viscosity is not well modelled by assuming local thermodynamic equilibrium. In spite of these effects, it is shown that massive (compact) discs can remain stable and not fragment, evolving rapidly to reduce their disc-to-star mass ratios through stellar accretion and radial spreading.Comment: 13 pages, 44 figures, accepted for publication in MNRA

Changing Signs:Testing How Sound-Symbolism Supports Early Word Learning

Learning a language involves learning how to map specific forms onto their associated meanings. Such mappings can utilise arbitrariness and non-arbitrariness, yet, our understanding of how these two systems operate at different stages of vocabulary development is still not fully understood. The Sound-Symbolism Bootstrapping Hypothesis (SSBH) proposes that sound-symbolism is essential for word learning to commence, but empirical evidence of exactly how sound symbolism influences language learning is still sparse. It may be the case that sound-symbolism supports acquisition of categories of meaning, or that it enables acquisition of individualized word meanings. In two Experiments where participants learned form-meaning mappings from either sound-symbolic or arbitrary languages, we demonstrate the changing roles of sound-symbolism and arbitrariness for different vocabulary sizes, showing that sound-symbolism provides an advantage for learning of broad categories, which may then transfer to support learning individual words, whereas an arbitrary language impedes acquisition of categories of sound to meaning

Hydrodynamic simulations of merging clusters of galaxies

We present the results of high-resolution AP3M+SPH simulations of merging clusters of galaxies. We find that the compression and shocking of the core gas during a merger can lead to large increases in bolometric X-ray luminosities and emission-weighted temperatures of clusters. Cooling flows are completely disrupted during equal-mass mergers, with the mass deposition rate dropping to zero as the cores of the clusters collide. The large increase in the cooling time of the core gas strongly suggests that cooling flows will not recover from such a merger within a Hubble time. Mergers with subclumps having one eighth of the mass of the main cluster are also found to disrupt a cooling flow if the merger is head-on. However, in this case the entropy injected into the core gas is rapidly radiated away and the cooling flow restarts within a few Gyr of the merger. Mergers in which the subcluster has an impact parameter of 500 kpc do not disrupt the cooling flow, although the mass deposition rate is reduced by ∼30 per cent. Finally, we find that equal mass, off-centre mergers can effectively mix gas in the cores of clusters, while head on mergers lead to very little mixing. Gas stripped from the outer layers of subclumps results in parts of the outer layers of the main cluster being well mixed, although they have little effect on the gas in the core of the cluster. None of the mergers examined here resulted in the intracluster medium being well mixed globally