16,493 research outputs found

    Multifrequency Observations of One of the Largest Supernova Remnants in the Local Group of Galaxies, LMC - SNR J0450-709

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    We present the results of new Australia Telescope Compact Array (ATCA) observations of one of the largest supernova remnants, SNR J0450-709, in the Local Group of galaxies. We found that this Large Magellanic Cloud (LMC) ob ject exhibits a typical morphology of an old supernova remnant (SNR) with diameter D=102x75+-1 pc and radio spectral index alpha=-0.43+-0.06. Regions of high polarisation were detected with peak value of ~40%.Comment: 7 pages, 4 figures, accepted for publication in Serbian Astronomical Journa

    Biological basis of child health 2: introduction to fertilisation, prenatal development and birth

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    This article is the second in a series called the biological basis of child health. It considers the period of development from fertilisation to birth, outlining the three stages of prenatal development - the germinal, embryonic and fetal stages. The article details how tissues and organs typically develop at each stage, and explains how and when deviations in development and congenital anomalies are likely to occur. It also describes some of the common congenital anomalies, their potential effects and their detection before or after birth. Information is also provided about the delivery of full-term infants, including the stages of labour

    Quenching of lamellar ordering in an n-alkane embedded in nanopores

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    We present an X-ray diffraction study of the normale alkane nonadecane C_{19}H_{40} embedded in nanoporous Vycor glass. The confined molecular crystal accomplishes a close-packed structure by alignment of the rod-like molecules parallel to the pore axis while sacrificing one basic principle known from the bulk state, i.e. the lamellar ordering of the molecules. Despite this disorder, the phase transitions observed in the confined solid mimic the phase behavior of the 3D unconfined crystal, though enriched by the appearance of a true rotator phase known only from longer alkane chains.Comment: 7 pages, 3 figure

    Universal trapping scaling on the unstable manifold for a collisionless electrostatic mode

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    An amplitude equation for an unstable mode in a collisionless plasma is derived from the dynamics on the two-dimensional unstable manifold of the equilibrium. The mode amplitude ρ(t)\rho(t) decouples from the phase due to the spatial homogeneity of the equilibrium, and the resulting one-dimensional dynamics is analyzed using an expansion in ρ\rho. As the linear growth rate γ\gamma vanishes, the expansion coefficients diverge; a rescaling ρ(t)γ2r(γt)\rho(t)\equiv\gamma^2\,r(\gamma t) of the mode amplitude absorbs these singularities and reveals that the mode electric field exhibits trapping scaling E1γ2|E_1|\sim\gamma^2 as γ0\gamma\rightarrow0. The dynamics for r(τ)r(\tau) depends only on the phase eiξe^{i\xi} where dϵk/dz=ϵkeiξ/2d\epsilon_{{k}} /dz=|{\epsilon_{{k}}}|e^{-i\xi/2} is the derivative of the dielectric as γ0\gamma\rightarrow0.Comment: 11 pages (Latex/RevTex), 2 figures available in hard copy from the Author ([email protected]); paper accepted by Physical Review Letter

    Scaling and singularities in the entrainment of globally-coupled oscillators

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    The onset of collective behavior in a population of globally coupled oscillators with randomly distributed frequencies is studied for phase dynamical models with arbitrary coupling. The population is described by a Fokker-Planck equation for the distribution of phases which includes the diffusive effect of noise in the oscillator frequencies. The bifurcation from the phase-incoherent state is analyzed using amplitude equations for the unstable modes with particular attention to the dependence of the nonlinearly saturated mode α|\alpha_\infty| on the linear growth rate γ\gamma. In general we find αγ(γ+l2D)|\alpha_\infty|\sim \sqrt{\gamma(\gamma+l^2D)} where DD is the diffusion coefficient and ll is the mode number of the unstable mode. The unusual (γ+l2D)(\gamma+l^2D) factor arises from a singularity in the cubic term of the amplitude equation.Comment: 11 pages (Revtex); paper submitted to Phys. Rev. Let

    Socioeconomic variations in women\u27s diets : what is the role of perceptions of the local food environment

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    Objectives : To test the contribution of perceived environmental factors (food availability, accessibility and affordability) to mediating socioeconomic variations in women&rsquo;s fruit, vegetable and fast food consumption. Methods : A community sample of 1580 women from 45 neighbourhoods provided survey data on their socioeconomic position (SEP) (education and income); diet (fruit, vegetable and fast food consumption); and the perceived availability of, access to and cost of healthy food in their local area. Results : Once perceived environmental variables were considered, the associations between SEP and diet were weak and non-significant, suggesting that socioeconomic differences in diet were almost wholly explained by perceptions of food availability, accessibility and affordability. Conclusions : Strategies to decrease socioeconomic inequalities in diet could involve promoting inexpensive ways to increase fruit and vegetable consumption, and ensuring that people of low SEP are aware that many healthy foods are available at relatively low cost. Future research should also confirm if perceptions match objective measures of food availability, accessibility and affordability, in order to address the real and/or perceived lack of healthy options in low SEP neighbourhoods.<br /

    Academic artisans in the research university

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    In the changing context of universities, organisational structures for teaching and research problematize academic roles. This paper draws on a critical realist analysis of surveys and interviews with academics from universities in England and Australia. It identifies important academic work, not captured simply in descriptions of teaching or research. It shows that many academics, who are not research high flyers nor award-winning teachers, carry out this essential work which contributes to the effective functioning of their universities. That work is referred to as academic artisanal work and the people who do it as academic artisans. Characteristics and examples of academic artisans are presented and the nature of artisanal work is explored. Implications for higher education management and for future studies are discussed. The paper points to an urgent need to better understand the complex nature of academic work

    Responding to university policies and initiatives: the role of reflexivity in the mid-career academic

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    How do academics make sense of university policies and strategic initiatives and act on them? Interviews were conducted with 27 mid-career academics in different disciplines, different research-intensive university environments and two countries (England and Australia). Data were analysed iteratively utilising a critical realist perspective, specifically, Archer’s modes of reflexivity. The paper argues that individuals’ responses to university policies and initiatives, to changes in policy and policy conflicts can at least partially be understood through interrogating the modes of reflexivity they employ

    Navigating the demands of academic work to shape an academic job

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    Findings from interviews with mid-career academics in English and Australian universities elucidate how academics interpret and navigate complex institutional contexts in shaping academic jobs. The paper argues that how they do this is a function of what they notice and respond to as well as the mode of reflexivity they employ. Three core areas are seen to affect academics sense of agency as they shape their own jobs: how they orient themselves to the world around them including the academic institution and department; their underlying goals and purposes as they seek to have a fulfilling role; and how they relate to structural conditions of the workplace. The paper argues that understanding academics’ differing foci of awareness in these areas is helpful to institutional policies and strategies
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