6,363 research outputs found

    A study of inner zone electron data and their comparison with trapped radiation models

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    A summary and intercomparison of recent inner radiation zone electron data are presented. The morphology of the inner radiation zone is described and the data compared with the current generation of inner zone trapped electron models. An analytic representation of the inner zone equatorial pitch angle distribution is presented. This model was based upon data from eight satellites and was used to reduce all data to the form of equatorial flux. Although no Starfish-free high energy electron measurements were available from the inner portion of the inner radiation zone, it was found that the AE-6 model provided a good description of the present solar maximum environment

    Tumour angiogenesis: The gap between theory and experiment

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    A common experimental technique for viewing in vivo angiogenesis utilises tumours implanted into a test animal cornea. The cornea is avascular but the tumour promotes vascularisation from the limbus and the new blood vessels can be readily observed through the transparent cornea. Many of the early mathematical models for tumour angiogenesis used this scenario as their experimental template and as such assumed that there is a large gap, of the order of 2 mm, between the tumour and neighbouring vasculature at the onset of angiogenesis. In this work we consider whether the assumption that there is a significant gap between the tumour and neighbouring vasculature is unique to intra-cornea tumour implants, or whether this characterises avascular tumour growth more generally. To do this we utilise a simple scaling argument, derive a multi-compartment model for tumour growth, and consider in vivo images. This analysis demonstrates that the corneal implant experiments and the corresponding mathematical models cannot generally be applied to a clinical setting

    Pedometer-determined physical activity and active transport in girls

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    <p>Abstract</p> <p>Background</p> <p>It is well established that the risk of insufficient physical activity is greater in girls than in boys, especially during the adolescent years. The promotion of active transport (AT) to and from school has been posited as a practical and convenient solution for increasing girls' total daily activity. However, there is limited information describing the associations between AT choices and girls' physical activity across a range of age, ethnic, and socioeconomic groups. The objectives of this study were to (1) investigate physical activity patterns in a large multiethnic sample of female children and adolescents, and to (2) estimate the physical activity associated with AT to and from school.</p> <p>Methods</p> <p>A total of 1,513 girls aged 5–16 years wore sealed multiday memory (MDM) pedometers for three weekdays and two weekend days. The ethnic composition of this sample was 637 European (42.1%), 272 Pacific Island (18.0%), 207 East Asian (13.7%), 179 Maori (11.8%), 142 South Asian (9.4%), and 76 from other ethnic groups (5%). Pedometer compliance and school-related AT were assessed by questionnaire.</p> <p>Results</p> <p>Mean weekday step counts (12,597 ± 3,630) were higher and less variable than mean weekend steps (9,528 ± 4,407). A consistent decline in daily step counts was observed with age: after adjustment for ethnicity and SES, girls in school years 9–10 achieved 2,469 (weekday) and 4,011 (weekend) fewer steps than girls in years 1–2. Daily step counts also varied by ethnicity, with Maori girls the most active and South Asian girls the least active. Overall, 44.9% of participants used AT for school-related travel. Girls who used AT to and from school averaged 1,052 more weekday steps than those who did not use AT. However, the increases in steps associated with AT were significant only in older girls (school years 5–10) and in those of Maori or European descent.</p> <p>Conclusion</p> <p>Our data suggest that adolescent-aged girls and girls of Asian descent are priority groups for future physical activity interventions. While the apparent benefits of school-related AT vary among demographic groups, promoting AT in girls appears to be a worthwhile strategy.</p

    Ferromagnetic superconductivity driven by changing Fermi surface topology

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    We introduce a simple but powerful zero temperature Stoner model to explain the unusual phase diagram of the ferromagnetic superconductor, UGe2. Triplet superconductivity is driven in the ferromagnetic phase by tuning the majority spin Fermi level through one of two peaks in the paramagnetic density of states (DOS). Each peak is associated with a metamagnetic jump in magnetisation. The twin peak DOS may be derived from a tight-binding, quasi-one-dimensional bandstructure, inspired by previous bandstructure calculations.Comment: 9 pages, 9 figures, REVTeX 4. Version 2: updated references and corrected typo

    Economic pressure, parent personality and child development: an interactionist analysis

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    "Der gegenwärtige ökonomische Abschwung in den USA und auf der ganzen Welt hat wieder die Aufmerksamkeit auf die Prozesse gelenkt, durch die Familien und Kinder durch ökonomische Härten belastet sind. Diese Studie betrachtet die Reaktionen auf ökonomische Härten in einer Stichprobe von Erwachsenen, die zum ersten Mal vor 20 Jahren befragt wurden, als sie noch Jugendliche waren. Insgesamt 271 der ursprünglichen G2 Jugendlichen (Durchschnittsalter M = 25.6 Jahre) nahmen an dieser Studie zusammen mit ihren kleinen Kindern (G3, Durchschnittsalter M = 2.31 Jahre zum ersten Erhebungszeitpunkt) und, in 81% der Fälle, zusammen mit dem anderen Elternteil des Kindes. Die Datenanalysen folgten einem interaktionistischen Modell und gingen davon aus, dass positive Persönlichkeitseigenschaften im Jugendalter der G2 weniger ökonomische Belastungen im Erwachsenenalter vorhersagen würden. Gleichzeitig wurde erwartet, dass diese positiven Persönlichkeitseigenschaften die negativen Familienprozesse aufhalten würden, die eine kompetente Entwicklung in G3 wahrscheinlich behindern. Die Befunde waren mit dem Selektionsaspekt im interaktionistischen Modell konsistent. Das Model sagte darüber hinaus vorher, dass ökonomischen Belastungen und andere familienbezogene Stressprozesse die Entwicklung von G3 über die frühere G2 Persönlichkeit beeinflussten. Der Sozialisationsaspekt im interaktionistischen Modell erhielt also auch Unterstützung. Die Befunde sprechen dafür, dass die Beziehung zwischen den ökonomischen Bedingungen und der Entwicklung von Kindern einen dynamischen Prozess aus Selektion und Sozialisation darstellt, der über Zeit und über Generationen zum Tragen kommt." (Autorenreferat)"The current economic downturn in the U.S. and around the world has refocused attention on the processes through which families and children are affected by economic hardship. This study examines the response to economic pressure of a cohort of youth first studied 20 years ago as adolescents and now grown to adulthood. A total of 271 of the original G2 adolescents (M age = 25.6 years) participated in the study with their young child (G3, M age = 2.31 years at the first time of assessment) and the child's other parent in 81% of the cases. Data analyses were guided by the interactionist model which proposed that positive G2 personality attributes during adolescence would predict lower economic pressure during adulthood and would diminish the negative family processes related to economic pressure expected to disrupt competent G3 development. The findings were consistent with this social selection aspect of the interactionist model. The model also predicted that economic pressure and other aspects of the related family stress process would affect G3 development net of earlier G2 personality. This social causation aspect of the interactionist model also received support. The findings suggest that the relationship between economic conditions and child development reflect a dynamic process of selection and causation that plays out over time and generations." (author's abstract

    Economic pressure, parent personality and child development : an interactionist analysis

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    That positive personality characteristics in the youth age of the G2 would predict less economic stresses in the adult age. At the same time, these positive personality traits were expected to stop the negative family processes that are likely to hinder a competent development in G3. The findings were consistent with the selection aspect in the interactionist model. The model also said beforehand that economic stress and other family-related stress processes influenced the development of G3 over the earlier G2 personality. The socialization aspect in the interactionist model thus also received support. However,The findings were consistent with this social selection. The model also predicted that of the G1 personality. This social causation of the interactionist model also received support. (Author\u27s abstract) The findings suggest that the relationship between the individual and the individual is the same. This social causation of the interactionist model also received support. (Author\u27s abstract) The findings suggest that the relationship between the individual and the individual is the same. This social causation of the interactionist model also received support. (Author\u27s abstract) The findings suggest that the relationship between the individual and the individual is the same

    Blaming Bill Gates AGAIN! Misuse, overuse and misunderstanding of performance data in sport

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    Recently in Sport, Education and Society, Williams and Manley (2014) argued against the heavy reliance on technology in professional Rugby Union and elite sport in general. In summary, technology is presented as an elitist, ‘gold standard’ villain that management and coaches use to exert control and by which players lose autonomy, identity, motivation, social interactions and expertise. In this article we suggest that the sociological interpretations and implications offered by Williams and Manley may be somewhat limited when viewed in isolation. In doing so, we identify some core methodological issues in Williams and Manley’s study and critically consider important arguments for utilising technology; notably, to inform coach decision making and generate player empowerment. Secondly, we present a different, yet perhaps equally concerning, practice-oriented interpretation of the same results but from alternative coaching and expertise literature. Accordingly, we suggest that Williams and Manley have perhaps raised their alarm prematurely, inappropriately and on somewhat shaky foundations. We also hope to stimulate others to consider contrary positions, or at least to think about this topic in greater detail. More specifically, we encourage coaches and academics to think carefully about what technology is employed, how and why, and then the means by which these decisions are discussed with and, preferably, sold to players. Certainly, technology can significantly enhance coach decision making and practice, while also helping players to optimise their focus, empowerment and independence in knowing how to achieve their personal and collective goals

    The surface accessibility of the glycine receptor M2-M3 loop is increased in the channel open state

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    Mutations in the extracellular M2-M3 loop of the glycine receptor (GlyR) alpha1 subunit have been shown previously to affect channel gating. In this study, the substituted cysteine accessibility method was used to investigate whether a structural rearrangement of the M2-M3 loop accompanies GlyR activation. All residues from R271C to V277C were covalently modified by both positively charged methanethiosulfonate ethyltrimethylammonium (MTSET) and negatively charged methanethiosulfonate ethylsulfonate (MTSES), implying that these residues form an irregular surface loop. The MTSET modification rate of all residues from R271C to K276C was faster in the glycine-bound state than in the unliganded state. MTSES modification of A272C, L274C, and V277C was also faster in the glycine-bound state. These results demonstrate that the surface accessibility of the M2-M3 loop is increased as the channel transitions from the closed to the open state, implying that either the loop itself or an overlying domain moves during channel activation

    Machine learning to detect marine animals in UAV imagery: effect of morphology, spacing, behaviour and habitat

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    Machine learning algorithms are being increasingly used to process large volumes of wildlife imagery data from unmanned aerial vehicles (UAVs); however, suitable algorithms to monitor multiple species are required to enhance efficiency. Here, we developed a machine learning algorithm using a low-cost computer. We trained a convolutional neural network and tested its performance in: (1) distinguishing focal organisms of three marine taxa (Australian fur seals, loggerhead sea turtles and Australasian gannets; body size ranges: 0.8–2.5 m, 0.6–1.0 m, and 0.8–0.9 m, respectively); and (2) simultaneously delineating the fine-scale movement trajectories of multiple sea turtles at a fish cleaning station. For all species, the algorithm performed best at detecting individuals of similar body length, displaying consistent behaviour or occupying uniform habitat (proportion of individuals detected, or recall of 0.94, 0.79 and 0.75 for gannets, seals and turtles, respectively). For gannets, performance was impacted by spacing (huddling pairs with offspring) and behaviour (resting vs. flying shapes, overall precision: 0.74). For seals, accuracy was impacted by morphology (sexual dimorphism and pups), spacing (huddling and creches) and habitat complexity (seal sized boulders) (overall precision: 0.27). For sea turtles, performance was impacted by habitat complexity, position in water column, spacing, behaviour (interacting individuals) and turbidity (overall precision: 0.24); body size variation had no impact. For sea turtle trajectories, locations were estimated with a relative positioning error of <50 cm. In conclusion, we demonstrate that, while the same machine learning algorithm can be used to survey multiple species, no single algorithm captures all components optimally within a given site. We recommend that, rather than attempting to fully automate detection of UAV imagery data, semi-automation is implemented (i.e. part automated and part manual, as commonly practised for photo-identification). Approaches to enhance the efficiency of manual detection are required in parallel to the development of effective implementation of machine learning algorithms

    Drying of complex suspensions

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    We investigate the 3D structure and drying dynamics of complex mixtures of emulsion droplets and colloidal particles, using confocal microscopy. Air invades and rapidly collapses large emulsion droplets, forcing their contents into the surrounding porous particle pack at a rate proportional to the square of the droplet radius. By contrast, small droplets do not collapse, but remain intact and are merely deformed. A simple model coupling the Laplace pressure to Darcy's law correctly estimates both the threshold radius separating these two behaviors, and the rate of large-droplet evacuation. Finally, we use these systems to make novel hierarchical structures.Comment: 4 pages, 4 figure
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