Visual Perceptual Difficulties and Under-Achievement at School in a Large Community-Based Sample of Children

Difficulties with visual perception (VP) are often described in children with neurological or developmental problems. However, there are few data regarding the range of visual perceptual abilities in populations of normal children, or on the impact of these abilities on children's day-to-day functioning. Methods Data were obtained for 4512 participants in an ongoing birth cohort study (Avon Longitudinal Study of Parents and Children; ALSPAC). The children's mothers responded to questions designed to elicit indications of visual perceptual difficulties or immaturity, when their children were aged 13 years. We examined associations with standardised school test results in reading and in mathematics at age 1314 years (SATS-KS3), accounting for potential confounders including IQ. Results Three underlying factors explained half the variance in the VP question responses. These correlated best with questions on interpreting cluttered scenes; guidance of movement and face recognition. The adjusted parameter estimates (95% CI) for the cluttered-scenes factor (0.05; 0.02 to 0.08; p<0.001) suggested positive associations with the reading test results whilst that for the guidance-of-movement factor (0.03; 0.00 to 0.06; p = 0.026) suggested positive association with the mathematics results. The raw scores were associated with both test results. Discussion VP abilities were widely distributed in this sample of 13-year old children. Lower levels of VP function were associated with under-achievement in reading and in mathematics. Simple interventions can help children with VP difficulties, so research is needed into practicable, cost-effective strategies for identification and assessment, so that support can be targeted appropriately

AustArch: a database of 14C and non-14C ages from archaeological sites in Australia: composition, compilation and review

This dataset represents an invaluable compilation of 14C and non-14C ages from archaeological sites for most of the 89 bio-regions of Australia. Critically harvesting some 5,000 14C and 500 non-14C dates from over 1,000 publications, the dataset provides information on each date in 26 fields including its location, site type, biogeographic zone, sample material, context and age details (including 13C and error). This data provides a comprehensive foundation for any regional archaeology in Australia illustrating past research foci, strengths and biases in sampling of bioregions, geomorphic context, site type, sample type, and adequacy of contextualisation (e.g. association with cultural events). Such datasets can improve time series and summed probability methods and are being used as a mainstream proxy to explore archaeological trends and specifically demographic fluctuations for the tropical northern, central arid zone and southern ocean provinces. Such reconstructions will always rely on coverage and adequacy of sampling (52 bioregions register less than 50 dates). While both closed rockshelter sites and open/midden sites account for a similar proportion of dates, less than 14% of sites have returned 4 or more dates. Given that 74% of dates fall within the Holocene epoch, this period is most amenable to archaeological enquiry at a fine-scaled regional level. For the Pleistocene era, larger scale questions such as occupation patterns during the LGM might reasonably be addressed and refined. The data may be re-used for studies of a) timing of colonisation of differing bioregions, b) characterising varying mobility patterns of groups occupying the arid zone, c) identifying gaps in previous research (the Great Victoria and Tanami Deserts), d) as proxy for demographic changes, e) the responses of groups to environmental stochasticity such as OIS2 and ENSO, f) the relationship between occupation and phases of rock art production through time, g) the nature of coastal occupation during lower sea stands and specifically following mid-Holocene stabilisation, and h) not least, as a fundamental building block for any regional archaeology of Australia

Australia's coastal living is at risk from sea level rise, but it's happened before

[Extract] With global sea levels expected to rise by up to a metre by 2100 we can learn much from archaeology about how people coped in the past with changes in sea level. In a study published this week in Quaternary Science Reviews, we looked at how changes in sea level affected different parts of Australia and the impact on people living around the coast. The study casts new light on how people adapt to rising sea levels of the scale projected to happen in our near future

Diversity and distribution of the dominant ant genus anonychomyrma (Hymenoptera: Formicidae) in the Australian wet tropics

Anonychomyrma is a dolichoderine ant genus of cool-temperate Gondwanan origin with a current distribution that extends from the north of southern Australia into the Australasian tropics. Despite its abundance and ecological dominance, little is known of its species diversity and distribution throughout its range. Here, we describe the diversity and distribution of Anonychomyrma in the Australian Wet Tropics bioregion, where only two of the many putative species are described. We hypothesise that the genus in tropical Australia retains a preference for cool wet rainforests reminiscent of the Gondwanan forests that once dominated Australia, but now only exist in upland habitats of the Wet Tropics. Our study was based on extensive recent surveys across five subregions and along elevation and vertical (arboreal) gradients. We integrated genetic (CO1) data with morphology to recognise 22 species among our samples, 20 of which appeared to be undescribed. As predicted, diversity and endemism were concentrated in uplands above 900 m a.s.l. Distribution modelling of the nine commonest species identified maximum temperature of the warmest month, rainfall seasonality, and rainfall of the wettest month as correlates of distributional patterns across subregions. Our study supported the notion that Anonychomyrma radiated from a southern temperate origin into the tropical zone, with a preference for areas of montane rainforest that were stably cool and wet over the late quaternary

Tectonics of Atlantic Canada

The tectonic history of Atlantic Canada is summarized according to a model of multiple ocean opening-closing cycles. The modern North Atlantic Ocean is in the opening phase of its cycle. It was preceded by an early Paleozoic lapetus Ocean whose cycle led to formation of the Appalachian Orogen. lapetus was preceded by the Neoproterozoic Uranus Ocean whose cycle led to formation of the Grenville Orogen. The phenomenon of coincident, or almost coincident orogens and modern continental margins that relate to repeated ocean opening-closing cycles is called the Accordion Effect. An understanding of the North Atlantic Ocean and its continental margins provides insights into the nature of lapetus and the evolution of the Appalachian Orogen. Likewise, an understanding of lapetus and the Appalachian Orogen raises questions about Uranus and the development of the Grenville Orogen. Modern tectonic patterns in the North Atlantic may have been determined by events that began before 1000 m.y. Résumé L'histoire tectonique de la portion atlantique du Canada est présenté comme la résultante d'une série d'ouvertures et de fermetures océaniques. Selon ce modèle tectonique, l'Atlantique nord moderne serait actuellement dans sa phase d'ouverture. Au début du Paléozoïque, le cycle précédent de l'océan lapétus a engendré l'orogène des Appalaches. L'océan lapétus a été précédé au Néoprotérozoïque par l'océan Uranus, dont le cycle d'ouverture-fermeture a engendré l'orogène de Grenville. Le phénomène de coïncidence ou quasi-coïncidence du profil des diverses orogènes et des marges continentale modernes qui correspond aux multiples cycles d'ouvertures-fermetures se nomme l'effet accordéon. La connaissance de l'océan Atlantique nord et de ses marges continentales permet d'appréhender certaines caractéristiques de la nature de l'océan lapétus et de l'orogène appalachîen. De même, une connaissance de l'océan lapétus et de l'orogène appalachîen suscite des pistes de questionnement sur l'océan Uranus et l'orogène de Grenville. Les profils de l'océan Atlantique nord actuelle pourrait bien être le résultat d'événements qui auraient débuté il y a environ 1 000 Ma

Sea-level change and demography during the last glacial termination and early Holocene across the Australian continent

Future changes in sea-level are projected to have significant environmental and social impacts, but we have limited understanding of comparable rates of change in the past. Using comprehensive palaeoenvironmental and archaeological datasets, we report the first quantitative model of the timing, spatial extent and pace of sea-level change in the Sahul region between 35-8 ka, and explore its effects on hunter-gatherer populations. Results show that the continental landmass (excluding New Guinea) increased to 9.80 million km2 during the Last Glacial Maximum (LGM), before a reduction of 2.12 million km2 (or ~21.6%) to the early Holocene (8 ka). Almost 90% of this inundation occurs during and immediately following Meltwater Pulse (MWP) 1a between 14.6 and 8 ka. The location of coastlines changed on average by 139 km between the LGM and early Holocene, with some areas >300 km, and at a rate of up to 23.7 m per year (~0.6 km land lost every 25-year generation). Spatially, inundation was highly variable, with greatest impacts across the northern half of Australia, while large parts of the east, south and west coastal margins were relatively unaffected. Hunter-gatherer populations remained low throughout (<30,000), but following MWP1a, increasing archaeological use of the landscape, comparable to a four-fold increase in populations, and indicative of large-scale migration away from inundated regions (notably the Bass Strait) are evident. Increasing population density resulting from MWP1a (from 1/655 km2 to 1/71 km2) may be implicated in the development of large and complex societies later in the Holocene. Our data support the hypothesis that late Pleistocene coastal populations were low, with use of coastal resources embedded in broad-ranging foraging strategies, and which would have been severely disrupted in some regions and at some time periods by sea-level change outpacing tolerances of mangals and other near-shore ecological communities

Vertical niche and elevation range size in tropical ants: implications for climate resilience

Aim: We propose that forest trees create a vertical dimension for ecological niche variation that generates different regimes of climatic exposure, which in turn drives species elevation distributions. We test this hypothesis by statistically modelling the vertical and elevation distributions and microclimate exposure of rainforest ants. Location: Wet Tropics Bioregion, Australia. Methods: We conducted 60 ground-to-canopy surveys to determine the vertical (tree) and elevation distributions, and microclimate exposure of ants (101 species) at 15 sites along four mountain ranges. We statistically modelled elevation range size as a function of ant species’ vertical niche breadth and exposure to temperature variance for 55 species found at two or more trees. Results: We found a positive association between vertical niche and elevation range of ant species: for every 3 m increase in vertical niche breadth, our models predict a ~150% increase in mean elevation range size. Temperature variance increased with vertical height along the arboreal gradient and ant species exposure to temperature variance explained some of the variation in elevation range size. Main conclusions: We demonstrate that arboreal ants have broader elevation ranges than ground-dwelling ants and are likely to have increased resilience to climatic variance. The capacity of species to expand their niche by climbing trees could influence their ability to persist over broader elevation ranges. We propose that wherever vertical layering exists—from oceans to forest ecosystems—vertical niche breadth is a potential mechanism driving macrogeographic distributional patterns and resilience to climate change

Directionally supervised cellular automaton for the initial peopling of Sahul

Reconstructing the patterns of Homo sapiens expansion out of Africa and across the globe has been advanced using demographic and travel-cost models. However, modelled routes are ipso facto influenced by migration rates, and vice versa. We combined movement ‘superhighways’ with a demographic cellular automaton to predict one of the world’s earliest peopling events — Sahul between 75,000–50,000 years ago. Novel outcomes from the superhighways weighted model include (i) an approximate doubling of the predicted time to continental saturation (~ 10,000 years) compared to that based on the directionally unsupervised model (~5,000 years), suggesting that rates of migration need to account for topographical constraints in addition to rate of saturation; (ii) a previously undetected movement corridor south through the centre of Sahul early in the expansion wave based on the scenarios assuming two dominant entry points into Sahul; and (iii) a better fit to the spatially de-biased, Signor-Lipps corrected layer of initial arrival inferred from dated archaeological material. Our combined model infrastructure provides a data-driven means to examine how people initially moved through, settled, and abandoned different regions of the globe

Investigating subantarctic ¹⁴C ages of different peat components: site and sample selection for developing robust age models in dynamic landscapes

Precise radiocarbon (¹⁴C) dating of sedimentary sequences is important for developing robust chronologies of environmental change, but sampling of suitable components can be challenging in highly dynamic landscapes. Here we investigate radiocarbon determinations of different peat size fractions from six peat sites, representing a range of geomorphological contexts on the South Atlantic subantarctic islands of the Falklands and South Georgia. To investigate the most suitable fraction for dating, 112 measurements were obtained from three components within selected horizons: a fine fraction 0.2 mm, and bulk material. We find site selection is critical, with locations surrounded by high-ground and/or relatively slowly accumulating sites more susceptible to the translocation of older carbon. Importantly, in locations with reduced potential for redeposition of material, our results show that there is no significant or systematic difference between ages derived from bulk material, fine or coarse (plant macrofossil) material, providing confidence in the resulting age model. Crucially, in areas comprising complex terrain with extreme relief, we recommend dating macrofossils or bulk carbon rather than a fine fraction, or employing comprehensive dating of multiple sedimentary fractions to determine the most reliable fraction(s) for developing a robust chronological framework