62 research outputs found

    Energetic electron precipitation driven by electromagnetic ion cyclotron waves from ELFIN's low altitude perspective

    Full text link
    We review comprehensive observations of electromagnetic ion cyclotron (EMIC) wave-driven energetic electron precipitation using data from the energetic electron detector on the Electron Losses and Fields InvestigatioN (ELFIN) mission, two polar-orbiting low-altitude spinning CubeSats, measuring 50-5000 keV electrons with good pitch-angle and energy resolution. EMIC wave-driven precipitation exhibits a distinct signature in energy-spectrograms of the precipitating-to-trapped flux ratio: peaks at 0.5 MeV which are abrupt (bursty) with significant substructure (occasionally down to sub-second timescale). Multiple ELFIN passes over the same MLT sector allow us to study the spatial and temporal evolution of the EMIC wave - electron interaction region. Using two years of ELFIN data, we assemble a statistical database of 50 events of strong EMIC wave-driven precipitation. Most reside at L=5-7 at dusk, while a smaller subset exists at L=8-12 at post-midnight. The energies of the peak-precipitation ratio and of the half-peak precipitation ratio (our proxy for the minimum resonance energy) exhibit an L-shell dependence in good agreement with theoretical estimates based on prior statistical observations of EMIC wave power spectra. The precipitation ratio's spectral shape for the most intense events has an exponential falloff away from the peak (i.e., on either side of 1.45 MeV). It too agrees well with quasi-linear diffusion theory based on prior statistics of wave spectra. Sub-MeV electron precipitation observed concurrently with strong EMIC wave-driven 1MeV precipitation has a spectral shape that is consistent with efficient pitch-angle scattering down to 200-300 keV by much less intense higher frequency EMIC waves. These results confirm the critical role of EMIC waves in driving relativistic electron losses. Nonlinear effects may abound and require further investigation

    ‘Getting the seat of your pants dirty’: space and place in ethnographic educational research

    Get PDF
    In this paper I consider the importance of space and place in ethnographic educational research. The paper draws on research that took place at Educational Video Center (EVC), a non-profit media education centre in New York City (NYC). In this paper I articulate EVC as a place imbued with meaning from the pedagogical practices that take place within and regarding it and argue for a consideration of spatiality in ethnographic educational research. I consider the role of the city landscape in order to identify how knowledge is emplaced and represented through digital, visual technology and conclude by outlining the criticality of spatialising our ethnographic practices

    Increased care at discharge from COVID-19: The association between pre-admission frailty and increased care needs after hospital discharge; a multicentre European observational cohort study

    Get PDF
    Background: The COVID-19 pandemic has placed significant pressure on health and social care. Survivors of COVID-19 may be left with substantial functional deficits requiring ongoing care. We aimed to determine whether pre-admission frailty was associated with increased care needs at discharge for patients admitted to hospital with COVID-19. Methods: Patients were included if aged over 18 years old and admitted to hospital with COVID-19 between 27 February and 10 June 2020. The Clinical Frailty Scale (CFS) was used to assess pre-admission frailty status. Admission and discharge care levels were recorded. Data were analysed using a mixed-effects logistic regression adjusted for age, sex, smoking status, comorbidities, and admission CRP as a marker of severity of disease. Results: Thirteen hospitals included patients: 1671 patients were screened, and 840 were excluded including, 521 patients who died before discharge (31.1%). Of the 831 patients who were discharged, the median age was 71 years (IQR, 58–81 years) and 369 (44.4%) were women. The median length of hospital stay was 12 days (IQR 6–24). Using the CFS, 438 (47.0%) were living with frailty (≥ CFS 5), and 193 (23.2%) required an increase in the level of care provided. Multivariable analysis showed that frailty was associated with an increase in care needs compared to patients without frailty (CFS 1–3). The adjusted odds ratios (aOR) were as follows: CFS 4, 1.99 (0.97–4.11); CFS 5, 3.77 (1.94–7.32); CFS 6, 4.04 (2.09–7.82); CFS 7, 2.16 (1.12–4.20); and CFS 8, 3.19 (1.06–9.56). Conclusions: Around a quarter of patients admitted with COVID-19 had increased care needs at discharge. Pre-admission frailty was strongly associated with the need for an increased level of care at discharge. Our results have implications for service planning and public health policy as well as a person's functional outcome, suggesting that frailty screening should be utilised for predictive modelling and early individualised discharge planning

    The ELFIN mission

    Get PDF
    The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93∘ inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime. Its primary science objective is to resolve the mechanism of storm-time relativistic electron precipitation, for which electromagnetic ion cyclotron (EMIC) waves are a prime candidate. From its ionospheric vantage point, ELFIN uses its unique pitch-angle-resolving capability to determine whether measured relativistic electron pitch-angle and energy spectra within the loss cone bear the characteristic signatures of scattering by EMIC waves or whether such scattering may be due to other processes. Pairing identical ELFIN satellites with slowly-variable along-track separation allows disambiguation of spatial and temporal evolution of the precipitation over minutes-to-tens-of-minutes timescales, faster than the orbit period of a single low-altitude satellite (Torbit ∼ 90 min). Each satellite carries an energetic particle detector for electrons (EPDE) that measures 50 keV to 5 MeV electrons with Δ E/E 1 MeV. This broad energy range of precipitation indicates that multiple waves are providing scattering concurrently. Many observed events show significant backscattered fluxes, which in the past were hard to resolve by equatorial spacecraft or non-pitch-angle-resolving ionospheric missions. These observations suggest that the ionosphere plays a significant role in modifying magnetospheric electron fluxes and wave-particle interactions. Routine data captures starting in February 2020 and lasting for at least another year, approximately the remainder of the mission lifetime, are expected to provide a very rich dataset to address questions even beyond the primary mission science objective.Published versio

    Accounting Research in the <i>Cornell Quarterly</i>: A Review with Suggestions for Future Research

    Full text link
    An analysis of accounting-related articles published in the Cornell Hospitality Quarterly shows a shift from prescription to description, with an increasing use of scientific research methods. The authors found that the literature has examined the industry’s use of the Uniform System of Accounts, cost management, and management control systems, including the effects of nonfinancial measures and the balanced scorecard. Although a uniform system of accounts offers consistency, it may limit a hotel manager’s ability to match costs with departmental revenues. Budgeting and capital budgeting are particularly difficult issues for the hospitality industry, due to the fact that most hotels involve independent parties as ownership and management. One oddity of the hospitality industry is that few managers adjust budgets to reflect operational outcomes. In addition to their review, the authors provide suggestions for future research.Potter2_Accounting_research.pdf: 392 downloads, before Aug. 1, 2020

    Accounting Research in the \u3ci\u3eCornell Quarterly\u3c/i\u3e: A Review with Suggestions for Future Research

    No full text
    An analysis of accounting-related articles published in the Cornell Hospitality Quarterly shows a shift from prescription to description, with an increasing use of scientific research methods. The authors found that the literature has examined the industry’s use of the Uniform System of Accounts, cost management, and management control systems, including the effects of nonfinancial measures and the balanced scorecard. Although a uniform system of accounts offers consistency, it may limit a hotel manager’s ability to match costs with departmental revenues. Budgeting and capital budgeting are particularly difficult issues for the hospitality industry, due to the fact that most hotels involve independent parties as ownership and management. One oddity of the hospitality industry is that few managers adjust budgets to reflect operational outcomes. In addition to their review, the authors provide suggestions for future research
    corecore