380 research outputs found
High-altitude gravity waves in the Martian thermosphere observed by MAVEN/NGIMS and modeled by a gravity wave scheme
First high-altitude observations of gravity wave (GW)-induced CO density
perturbations in the Martian thermosphere retrieved from NASA's NGIMS
instrument on board the MAVEN satellite are presented and interpreted using the
extended GW parameterization of Yi\u{g}it et al. [2008] and the Mars Climate
Database as an input. Observed relative density perturbations between 180-220
km of 20-40 % demonstrate appreciable local time, latitude, and altitude
variations. Modeling for the spatiotemporal conditions of the MAVEN
observations suggests that GWs can directly propagate from the lower atmosphere
to the thermosphere, produce appreciable dynamical effects, and likely
contribute to the observed fluctuations. Modeled effects are somewhat smaller
than the observed but their highly variable nature is in qualitative agreement
with observations. Possible reasons for discrepancies between modeling and
measurements are discussed.Comment: Accepted for publication in Geophysical Research Letters (GRL).
Special section: First Results from the MAVEN Mission to Mar
Observations of Typhoon Generated Gravity Waves From the CIPS and AIRS Instruments and Comparison to the High-Resolution ECMWF Model
The satellite-based Cloud Imaging and Particle Size (CIPS) instrument and Atmospheric Infrared Sounder (AIRS) observed concentric gravity waves (GWs) generated by Typhoon Yutu in late October 2018. This work compares CIPS and AIRS nadir viewing observations of GWs at altitudes of 50–55 and 30–40 km, respectively, to simulations from the high-resolution European Centre for Medium-Range Weather Forecasting Integrated Forecasting System (ECMWF-IFS) and ECMWF reanalysis v5 (ERA5). Both ECMWF-IFS with 9 km and ERA5 with 31 km horizontal resolution show concentric GWs at similar locations and timing as the AIRS and CIPS observations. The GW wavelengths are ∼225–236 km in ECMWF-IFS simulations, which compares well with the wavelength inferred from the observations. After validation of ECMWF GWs, five category five typhoon events during 2018 are analyzed using ECMWF to obtain characteristics of concentric GWs in the Western Pacific regions. The amplitudes of GWs in the stratosphere are not strongly correlated with the strength of typhoons, but are controlled by background wind conditions. Our results confirm that amplitudes and shapes of concentric GWs observed in the stratosphere and lowermost mesosphere are heavily influenced by the background wind conditions.</p
Reviewing research evidence and the case of participation in sport and physical recreation by black and minority ethnic communities
The paper addresses the implications of using the process of systematic review in the many areas of leisure where there is a dearth of material that would be admitted into conventional Cochrane Reviews. This raises important questions about what constitutes legitimate knowledge, questions that are of critical import not just to leisure scholars, but to the formulation of policy. The search for certainty in an area that lacks conceptual consensus results in an epistemological imperialism that takes a geocentric form. While clearly, there is a need for good research design whatever the style of research, we contend that the wholesale rejection of insightful research is profligate and foolhardy. A mechanism has to be found to capitalise on good quality research of whatever form. In that search, we draw upon our experience of conducting a review of the material available on participation in sport and physical recreation by people from Black and minority ethnic groups. The paper concludes with a proposal for a more productive review process that makes better use of the full panoply of good quality research available. © 2012 © 2012 Taylor & Francis
Less time to study, less well prepared for work, yet satisfied with higher education: A UK perspective on links between higher education and the labour market
This paper explores graduates’ views on the relationship between higher education and employment. It draws on a major European study involving graduates five years after graduation and highlights similarities and differences between UK graduates’ experiences and their European counterparts. Specifically we address questions raised in the study about subjects studied and their relevance to entry into the labour market, if the academic level obtained was appropriate, whether graduates, with hindsight of five years, would choose the same subjects or the same institution again, and if they were satisfied with their current job. Such specific questions relate to broader perspectives such as the perceived value of higher education study in relation to initial employment and future life histories. These have to be seen in the context of cultural differences in higher education systems at the time of the research and, perhaps increasing convergences in light of the Bologna agreement
Characterization of Joint Resistance and Performance Degradation of the Extravehicular Mobility Unit Spacesuit: A Pilot Study
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On the Specification of Upward-Propagating Tides for ICON Science Investigations.
The National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) will provide a physics-based context for the interpretation of ICON measurements. To optimize the realism of the model simulations, ICON wind and temperature measurements near the ~97 km lower boundary of the TIEGCM will be used to specify the upward-propagating tidal spectrum at this altitude. This will be done by fitting a set of basis functions called Hough Mode Extensions (HMEs) to 27-day mean tidal winds and temperatures between 90 and 105 km altitude and between 12°S and 42°N latitude on a day-by-day basis. The current paper assesses the veracity of the HME fitting methodology given the restricted latitude sampling and the UT-longitude sampling afforded by the MIGHTI instrument viewing from the ICON satellite, which will be in a circular 27° inclination orbit. These issues are investigated using the output from a reanalysis-driven global circulation model, which contains realistic variability of the important tidal components, as a mock data set. ICON sampling of the model reveals that the 27-day mean diurnal and semidiurnal tidal components replicate well the 27-day mean tidal components obtained from full synoptic sampling of the model, but the terdiurnal tidal components are not faithfully reproduced. It is also demonstrated that reconstructed tidal components based on HME fitting to the model tides between 12°S and 42°N latitude provide good approximations to the major tidal components expected to be encountered during the ICON mission. This is because the constraints provided by fitting both winds and temperatures over the 90-105 km height range are adequate to offset the restricted sampling in latitude. The boundary conditions provided by the methodology described herein will greatly enhance the ability of the TIEGCM to provide a physical framework for interpreting atmosphere-ionosphere coupling in ICON observations due to atmospheric tides
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Daily Variability in the Terrestrial UV Airglow
New capability for observing conditions in the upper atmosphere comes with the implementation of global ultraviolet (UV) imaging from geosynchronous orbit. Observed by the NASA GOLD mission, the emissions of atomic oxygen (OI) and molecular nitrogen (N2) in the 133–168-nm range can be used to characterize the behavior of these major constituents of the thermosphere. Observations in the ultraviolet from the first 200 days of 2019 indicate that the oxygen emission at 135.6 nm varies much differently than the broader Lyman-Birge-Hopfield (LBH) emission of N2. This is determined from monitoring the average instrument response from two roughly 1000 km2 areas, well separated from one another, at the same time of each day. Variations in the GOLD response to UV emissions in the monitored regions are determined, both in absolute terms and relative to a running 7-day average of GOLD measurements. We find that variations in N2 emissions in the two separate regions are significantly correlated, while oxygen emissions, observed in the same fixed geographic regions at the same universal time each day, exhibit a much lower correlation, and exhibit no correlation with the N2 emissions in the same regions. This indicates that oxygen densities in the airglow-originating altitude range of 150–200 km vary independently from the variations in nitrogen, which are so well correlated across the dayside to suggest a direct connection to variation in solar extreme-UV flux. The relation of the atomic oxygen variations to solar and geomagnetic activity is also shown to be low, suggesting the existence of a regional source that modifies the production of atomic oxygen in the thermosphere.</p
Representations of mental health and arts participation in the national and local British press, 2007-2015
We analysed news articles published in national and local British newspapers between 2007 and 2015 to understand 1) how mental health and arts participation were framed and 2) how the relationships between participants in arts initiatives were conceptualised. Using corpus-assisted qualitative frame analysis, we identified frames of recovery, stigma and economy. The recovery frame, which emphasised that mental illness can be treated similarly to physical illness, positioned arts participation as a form of therapy that can complement or substitute medication. The stigma frame presented arts participation as a mechanism for challenging social conceptions that mentally ill individuals are incapable of productive work. The economy frame discussed the economic burden of mentally ill individuals and portrayed arts participation as facilitating their return to employment. Using thematic analysis, which paid attention to the representation of social actors, we found that service users were identified as the prime beneficiaries of arts initiatives and arts participation was conceptualised as a way to bring people with mental health issues together. We discuss these findings against existing research on media representations of mental health and the concept of ‘mutual recovery’ and suggest what wider concurrent developments in the areas of mental health and the media may account for the uncovered frames and themes
Administrative Managers – A Critical Link
Institutional responses to changes in the higher education environment have caused movements in the roles and identities of administrative managers in UK universities. These shifts have highlighted the problem for individuals of balancing traditional public service considerations of administration with institutional innovation and development. Administrative managers find themselves not only acting as independent arbiters, giving impartial advice on the basis of professional expertise, but also becoming involved in political judgements about institutional futures. They increasingly undertake an interpretive function between the various communities of the university and its external partners. As the boundaries of the university have become more permeable, administrative and academic management have inter-digitated, and hybrid roles have developed. In undertaking increasingly complex functions, therefore, administrative managers play a critical role in linking the academic and executive arms of governance in the university
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