Children's active play: self-reported motivators, barriers and facilitators

Physical activity has important benefits for children's physical health and mental wellbeing, but many children do not meet recommended levels. Research suggests that active play has the potential to make a valuable contribution to children's overall physical activity, whilst providing additional cognitive, social and emotional benefits. However, relatively little is known about the determinants of UK children's active play. Understanding these factors provides the critical first step in developing interventions to increase children's active play, and therefore overall physical activity. Eleven focus groups were conducted with 77, 10-11 year old children from four primary schools in Bristol, UK. Focus groups examined: (i) factors which motivate children to take part in active play; (ii) factors which limit children's active play and (iii) factors which facilitate children's active play. All focus groups were audio-taped and transcribed verbatim. Data were analysed using a thematic approach. Children were motivated to engage in active play because they perceived it to be enjoyable, to prevent boredom, to have physical and mental health benefits and to provide freedom from adult control, rules and structure. However, children's active play was constrained by a number of factors, including rainy weather and fear of groups of teenagers in their play spaces. Some features of the physical environment facilitated children's active play, including the presence of green spaces and cul-de-sacs in the neighbourhood. Additionally, children's use of mobile phones when playing away from home was reported to help to alleviate parents' safety fears, and therefore assist children's active play. Children express a range of motivational and environmental factors that constrain and facilitate their active play. Consideration of these factors should improve effectiveness of interventions designed to increase active play

The theory of expanded, extended, and enhanced opportunities for youth physical activity promotion

Background Physical activity interventions targeting children and adolescents (≤18 years) often focus on complex intra- and inter-personal behavioral constructs, social-ecological frameworks, or some combination of both. Recently published meta-analytical reviews and large-scale randomized controlled trials have demonstrated that these intervention approaches have largely produced minimal or no improvements in young people\u27s physical activity levels. Discussion In this paper, we propose that the main reason for previous studies\u27 limited effects is that fundamental mechanisms that lead to change in youth physical activity have often been overlooked or misunderstood. Evidence from observational and experimental studies is presented to support the development of a new theory positing that the primary mechanisms of change in many youth physical activity interventions are approaches that fall into one of the following three categories: (a) the expansion of opportunities for youth to be active by the inclusion of a new occasion to be active, (b) the extension of an existing physical activity opportunity by increasing the amount of time allocated for that opportunity, and/or (c) the enhancement of existing physical activity opportunities through strategies designed to increase physical activity above routine practice. Their application and considerations for intervention design and interpretation are presented. Summary The utility of these mechanisms, referred to as the Theory of Expanded, Extended, and Enhanced Opportunities (TEO), is demonstrated in their parsimony, logical appeal, support with empirical evidence, and the direct and immediate application to numerous settings and contexts. The TEO offers a new way to understand youth physical activity behaviors and provides a common taxonomy by which interventionists can identify appropriate targets for interventions across different settings and contexts. We believe the formalization of the TEO concepts will propel them to the forefront in the design of future intervention studies and through their use, lead to a greater impact on youth activity behaviors than what has been demonstrated in previous studies

Taphonomy and palaeoecology of the emuellid trilobite 'Balcoracania dailyi' (early Cambrian, South Australia)

Monospecific assemblages of the trilobite 'Balcoracania dailyi' occur in lower Cambrian strata within the Adelaide Geosyncline in South Australia. Biostratinomic data from single bedding plane assemblages within the Warragee and Coads Hill Members of the Billy Creek Formation and White Point Conglomerate reveal a range of taphonomic signatures from census to within-habitat, time-averaged assemblages. These assemblages are interpreted as having inhabited protected, shallow, marginal marine environments. Size–frequency distributions, coupled with taphonomic data, show that the Warragee Member census assemblage represents a living population in a physically stressful environment within a tidally-influenced lagoon, while the original population structure of the Coads Hill Member and White Point Conglomerate assemblages has been lost due to varying degrees of taphonomic overprinting. Integration of taphonomic, stratigraphic and sedimentological data supports the interpretation of 'B. dailyi' as representing an opportunistic species. A preserved body cluster from the Warragee Member assemblage is considered to characterise a congregation formed for the purpose of synchronous reproduction and ecdysis, representing one of the oldest examples of gregarious behaviour in the arthropod fossil record. Furthermore, by analogy with modern horseshoe crabs, the high number of juveniles (i.e., protaspides and early meraspides) within the same assemblage are believed to be constituents of a nursery within the intertidal zone, with adults migrating into the shallows to copulate and spawn. Preserved moult ensembles from the Coads Hill Member and White Point Conglomerate have enabled the description of exuviation techniques for 'B. dailyi'

The geological context of the Lower Cambrian (Series 2) Emu Bay Shale Lagerstätte and adjacent stratigraphic units, Kangaroo Island, South Australia

The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstätte, which is by far the most important Burgess Shale-type (BST) deposit in Australia, occurs mainly in the bottom 10 m of the Emu Bay Shale at Big Gully on the north coast of Kangaroo Island, South Australia. In this area, the exposed Cambrian succession commences with the White Point Conglomerate, the bulk of which comprises a crudely cross-bedded cobble to boulder conglomerate with minor mudstone and sandstone facies. The conglomeratic horizons thin markedly to the south. The White Point Conglomerate was deposited as coalesced fan deltas derived from an uplifted tectonic margin immediately to the north of the present coastline. The White Point Conglomerate is overlain by the sandstone, siltstone and conglomerate beds of the Marsden Sandstone (new name), the basal 3 m of which is a distinctive fossiliferous argillaceous limestone and shale, the Rouge Mudstone Member (new name). Syndepositional folding and faulting affected both the White Point Conglomerate and Marsden Sandstone prior to the deposition of the Emu Bay Shale, the base of which represents a sequence boundary. The Lagerstätte occurs within dark grey to black laminated micaceous mudstone facies, some of which show evidence of syndepositional disturbance, and are interpreted to have been deposited in isolated stagnant, anoxic toxic depressions on the sea floor, beneath a normally oxic water column, with a sharp redox boundary at the sediment-water interface; below this boundary the pore water was anoxic. Thin (up to 20 cm) structureless fine sandstone horizons within the mudstone are interpreted as either sediment gravity flow or storm deposits. The Lagerstätte-bearing mudstone beds thin southwards and disappear 500-600 m south of the coast. The Emu Bay Shale coarsens upwards; arthropod tracks are abundant in fine sandstone beds towards the top of the Emu Bay Shale. In coastal sections the sandstone facies of the Boxing Bay Formation rest conformably on the Emu Bay Shale; inland the contact is channelled

Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia

Despite the status of the eye as an "organ of extreme perfection", theory suggests that complex eyes can evolve very rapidly. The fossil record has, until now, been inadequate in providing insight into the early evolution of eyes during the initial radiation of many animal groups known as the Cambrian explosion. This is surprising because Cambrian Burgess-Shale-type deposits are replete with exquisitely preserved animals, especially arthropods, that possess eyes. However, with the exception of biomineralized trilobite eyes, virtually nothing is known about the details of their optical design. Here we report exceptionally preserved fossil eyes from the Early Cambrian (~515 million years ago) Emu Bay Shale of South Australia, revealing that some of the earliest arthropods possessed highly advanced compound eyes, each with over 3,000 large ommatidial lenses and a specialized 'bright zone'. These are the oldest non-biomineralized eyes known in such detail, with preservation quality exceeding that found in the Burgess Shale and Chengjiang deposits. Non-biomineralized eyes of similar complexity are otherwise unknown until about 85 million years later. The arrangement and size of the lenses indicate that these eyes belonged to an active predator that was capable of seeing in low light. The eyes are more complex than those known from contemporaneous trilobites and are as advanced as those of many living forms. They provide further evidence that the Cambrian explosion involved rapid innovation in fine-scale anatomy as well as gross morphology, and are consistent with the concept that the development of advanced vision helped to drive this great evolutionary event

Early Cambrian Arthropods from the Emu Bay Shale Lagerstätte, South Australia

The Emu Bay Shale Lagerstätte, located on the north coast of Kangaroo Island, South Australia, is the most important Burgess Shale-type Cambrian fossil locality in Australia. In 1952, R.C. Sprigg first discovered fossils in the Emu Bay Shale near the Emu Bay jetty as part of the Geological Survey of South Australia regional mapping programme (Sprigg et al., 1954; Sprigg, 1955). However, due to an accident, Sprigg was unable to carry out detailed work to the east of Emu Bay. The Emu Bay Shale Lagerstätte site at Big Gully, located 3 km east of Emu Bay (Fig. 1), was discovered along the coastline immediately adjacent to Big Gully by B. Daily during his doctoral studies. The first fossils collected included superb articulated specimens of 'Redlichia' up to 25 cm in length. Daily (1956, p. 126) was also the first to publish information on the Lagerstätte, recording the presence of the trilobites 'Redlichia' n. sp. and cf. 'Lusiatops', plus 'Isoxys' n. sp., an unidentified crustacean and annelids; this represented his Faunal Assemblage 12. The trilobite species referred to as "cf. Lusiatops" by Daily (1956) was later described as 'Estaingia bilobata' by Pocock (1964), although the illustrated specimens were not sourced from the Lagerstätte. Jell (in Bengtson et al., 1990) formally described specimens of 'Redlichia' from Big Gully as 'R. takooensis' Lu, 1950. M.F. Glaessner, M. Wade and B. McGowran collected material (including nonmineralised taxa) in December 1956 (B. McGowran, pers. comm., December 2007), but no formal descriptions were published until Glaessner (1979) described the bivalved arthropods 'Isoxys communis' and 'Tuzoia australis', the palaeoscolecid priapulid 'Palaeoscolex antiquus', plus 'Myoscolex ateles' and 'Vetustovermis planus' of uncertain affinities. Glaessner (1979) noted that there were no signs of trace fossils in his material; he suggested deposition as a thanatocoenosis within a reducing environment