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3 results

  • 5 - Lagrangian and Objective Eulerian Coherent Structures

  • George Haller, ETH Zurich
  • Book:
    Transport Barriers and Coherent Structures in Flow Data
    Published online:
    20 February 2023
    Print publication:
    16 March 2023, pp 141-241

  • Summary

    Here, we take our first step to discover barriers to transport outside the idealized setting of temporally recurrent (steady, periodic or quasiperiodic) velocity fields. While we can no longer hope for even approximately recurring material surfaces in this general setting, we can certainly look for material surfaces that remain coherent. We perceive a material surface to be coherent if it preserves the spatial integrity without developing smaller scales. Those smaller scales would manifest themselves as protrusions from either side of the material surface without a break-up of that surface. In other words, using the terminology of the Introduction, we seek advective transport barriers in nonrecurrent flows as Lagrangian coherent structures (LCS). We will refer to this instantaneous limit of LCSs as objective Eulerian coherent structures (OECSs). These Eulerian structures act as LCSs over infinitesimally short time scales and hence their time-evolution is not material. Despite being nonmaterial, OECSs have advantages and important applications in unsteady flow analysis, as we will discuss separately.

  • Study of Stealth CMEs and associated ICMEs

  • Miral Bhatt, Nandita Srivastava, Ravindra Jadhav
  • Journal:
    Proceedings of the International Astronomical Union / Volume 13 / Issue S340 / February 2018
    Published online by Cambridge University Press:
    27 November 2018, pp. 89-90
    Print publication:
    February 2018
    • Article
      • You have access
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  • Generally Coronal Mass Ejections (CMEs) are large eruptions of plasma and magnetic field from the Sun into interplanetary space. CMEs are most frequently associated with a variety of phenomena occurring in the lower corona before, during and after onset of eruption and generally are visible in coronagraph observation. Stealth CMEs do not obviously exhibit any of the low-coronal signatures (LCS) like solar flares, flows, jets, coronal dimmings or brightenings, filament eruptions or the formation of flare loop arcades. In this study, five stealth CMEs are selected using LASCO/SOHO CME catalogue and associated ICMEs (Interplanetaty CMEs) are identified using data from STEREO, ACE and WIND.

  • Looming cognitive style and quality of life in a cancer cohort

  • Tomer T. Levin, John Riskind, Yuelin Li
  • Journal:
    Palliative & Supportive Care / Volume 8 / Issue 4 / December 2010
    Published online by Cambridge University Press:
    28 September 2010, pp. 449-454
  • Objective:

    Looming cognitive styles (LCS) bias the velocity of potential threats and have been implicated in anxiety and depression vulnerability. This study aims to explore their contribution to impaired quality of life (QOL), beyond that of depression and anxiety, in a cancer cohort.

    Method:

    In a cross-sectional design, an ambulatory chronic lymphocytic leukemia (CLL) cohort completed a psychological battery that included the Beck Depression and Anxiety Inventories, the SF-36 Health Survey, the Functional Assessment of Chronic Illness Therapy (FACT), the Looming Cognitive Style Questionnaire (LCSQ), and the Looming Cancer measure.

    Results:

    The Looming Cancer measure correlated significtly with overall QOL (FACT-G, p = 0.005). This effect was largely due to the contribution of emotional QOL (Mental Component Score: SF-36, p = 0.001; FACT-emotional, p = 0.001) and functional QOL (FACT-functional, p = 0.001). Looming, unlike anxiety and depression, did not correlate with a worse physical QOL (Physical Component Score: SF-36, FACT-physical). Looming did not impact on social QOL. Hierarchical regression analysis showed that looming predicted 5.4% of the varience on the FACT-emotional, 5.1% on the Mental Component Score (SF-36), and 9.3% on the mental health subscale (SF-36), above and beyond the varience predicted by a constellation of psychosocial factors (including age, marital status, education, income) and the combined effect of depression and anxiety

    Significance of results:

    LCS predicts worse emotional and functional QOL, above and beyond the contribution of anxiety, depression, and other psycho-social variables. This suggests that it makes a unique contribution to a worse QOL. Nevertheless, the looming construct still remains primarily a research tool in psycho-oncology at this time.