1,219 research outputs found

    Integrated mass transportation system study/definition/implementation program definition

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    Specific actions needed to plan and effect transportation system improvements are identified within the constraints of limited financial, energy and land use resources, and diverse community requirements. A specific program is described which would develop the necessary generalized methodology for devising improved transportation systems and evaluate them against specific criteria for intermodal and intramodal optimization. A consistent, generalized method is provided for study and evaluation of transportation system improvements

    An implicit method for radiative transfer with the diffusion approximation in SPH

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    An implicit method for radiative transfer in SPH is described. The diffusion approximation is used, and the hydrodynamic calculations are performed by a fully three--dimensional SPH code. Instead of the energy equation of state for an ideal gas, various energy states and the dissociation of hydrogen molecules are considered in the energy calculation for a more realistic temperature and pressure determination. In order to test the implicit code, we have performed non--isothermal collapse simulations of a centrally condensed cloud, and have compared our results with those of finite difference calculations performed by MB93. The results produced by the two completely different numerical methods agree well with each other.Comment: 25 pages, 9 figure

    Star Formation with Adaptive Mesh Refinement Radiation Hydrodynamics

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    I provide a pedagogic review of adaptive mesh refinement (AMR) radiation hydrodynamics (RHD) methods and codes used in simulations of star formation, at a level suitable for researchers who are not computational experts. I begin with a brief overview of the types of RHD processes that are most important to star formation, and then I formally introduce the equations of RHD and the approximations one uses to render them computationally tractable. I discuss strategies for solving these approximate equations on adaptive grids, with particular emphasis on identifying the main advantages and disadvantages of various approximations and numerical approaches. Finally, I conclude by discussing areas ripe for improvement.Comment: 8 pages, to appear in the Proceedings of IAU Symposium 270: Computational Star Formatio

    Apollo 7 retrofire and reentry of service propulsion module. Further study of Intelsat 2 F-2 apogee burn

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    Photography of Apollo 7 retrofire and service propulsion module reentry and apogee burn of Intelsat 2 F-2 satellit

    The role of accretion disks in the formation of massive stars

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    We present radiation hydrodynamics simulations of the collapse of massive pre-stellar cores. We treat frequency dependent radiative feedback from stellar evolution and accretion luminosity at a numerical resolution down to 1.27 AU. In the 2D approximation of axially symmetric simulations, it is possible for the first time to simulate the whole accretion phase of several 10^5 yr for the forming massive star and to perform a comprehensive scan of the parameter space. Our simulation series show evidently the necessity to incorporate the dust sublimation front to preserve the high shielding property of massive accretion disks. Our disk accretion models show a persistent high anisotropy of the corresponding thermal radiation field, yielding to the growth of the highest-mass stars ever formed in multi-dimensional radiation hydrodynamics simulations. Non-axially symmetric effects are not necessary to sustain accretion. The radiation pressure launches a stable bipolar outflow, which grows in angle with time as presumed from observations. For an initial mass of the pre-stellar host core of 60, 120, 240, and 480 Msol the masses of the final stars formed in our simulations add up to 28.2, 56.5, 92.6, and at least 137.2 Msol respectively.Comment: 4 pages, 2 figures, Computational Star Formation Proceedings IAU Symposium No. 270, 2010, Ed.: J. Alves, B. Elmegreen, J. Girart & V. Trimbl

    Learning to facilitate arts-in-health programmes: a case study of musicians facilitating creative interventions for mothers with symptoms of postnatal depression

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    There is growing research documenting the effects of arts-in-health interventions on diverse participant groups. However, the impact of interventions on facilitators remains largely lacking. Drawing on a case study project, this article reports on a qualitative study to understand the practices, challenges, enablers and impacts for musicians of facilitating creative interventions for women with symptoms of postnatal depression. Thematic analysis revealed that the musicians used specific practices to successfully facilitate their activities, relying on a balance of forward-planning with the need to retain flexibility and provide women with autonomy and opportunities for social bonding. Key challenges included coping with the emotional impact of the project as well as facilitating different types of creative activities, while a strong sense of team and the structure of the interventions supported delivery. Finally, the project enabled the development of both generic and context-specific creative facilitation skills, and also contributed to the facilitators’ wellbeing. The logistical, educational and support implications for other practitioners seeking to establish such interventions are considered within the context of arts-in-health and musicians’ education

    When all solutions of x′ = −∑ qi(t) x(t − Ti(t)) oscillate

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    AbstractIn this paper the long-term behavior of solutions to the equation in the title are examined, where qi(t) and Ti(t) are positive. In particular, it is shown that if lim inft → ∝ ∑i = 1n Ti(t) qi(t) > 1/e, all solutions oscillate about 0 infinitely often

    How group singing facilitates recovery from the symptoms of postnatal depression: a comparative qualitative study

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    Background: Previous research has demonstrated that making music can enhance positive emotions as well as support positive psychological functioning. However, studies tend to be limited by lack of comparison with other psychosocial interventions. This study builds on a three-arm randomised controlled trial (RCT) that demonstrated that group singing for mothers and babies, but not group creative play, can lead to faster recovery from moderate-severe symptoms of postnatal depression than usual care. The aim was to elucidate the mechanisms of the group singing intervention in order to account for its recovery properties. Methods: Qualitative research was conducted with 54 mothers who had experienced symptoms of postnatal depression. Mothers completed a 10-week programme of either group singing or group creative play as part of the wider RCT study. Data were collected via a series of 10 semi-structured focus groups conducted at the end of each 10-week programme. These were designed to elicit subjective and constructed experiences of the singing and play interventions and were analysed inductively for emergent themes. Results: Five distinctive features of the group singing emerged: (i) providing an authentic, social and multicultural creative experience, (ii) ability to calm babies; (iii) providing immersive ‘me time’ for mothers; (iv) facilitating a sense of achievement and identity; (v) enhancing mother-infant bond. Conclusions: Community group singing interventions may reduce symptoms of postnatal depression through facilitating a functional emotional response rooted in the needs of new motherhood. These features are of relevance to others seeking to implement creative interventions for maternal mental health. Trial registration: NCT02526407. Registered 18 August 2015
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