5,187 research outputs found
Comparative analyses of space-to-space central power stations
The technological and economical impact of a large central power station in Earth orbit on the performance and cost of future spacecraft and their orbital transfer systems are examined. It is shown that beaming power to remote users cannot be cost effective if the central power station uses the same power generation system that is readily available for provision of onboard power and microwave transmission and reception of power through space for use in space is not cost competitive with onboard power or propulsion systems. Laser and receivers are required to make central power stations feasible. Remote power transmission for propulsion of orbital transfer vehicles promises major cost benefits. Direct nuclear pumped or solar pumped laser power station concepts are attractive with laser thermal and laser electric propulsion systems. These power stations are also competitive, on a mass and cost basis, with a photovoltaic power station
The orbital recovery problem. Part II - Application of analysis technique to selection of recovery sites for return from low circular orbits
Lateral range requirements used in selecting spacecraft landing recovery sites for return from low circular orbit
Early identification of wound infection: understanding wound odour
Malodorous wounds can be distressing for patients and their families, negatively impacting on quality-of-life outcomes. For health professionals malodorous wounds can also cause distress manifesting in feelings of disgust when faced with a wound emitting an unpleasant or repulsive odour. There has been investigation into the management of controlling odour particularly in relation to fungating wounds. However, there is limited research that explores techniques for early identification and recognition of wound odours that may be indicative of infection. Electronic nose technology has received some attention, but to date has not been integrated into either diagnostics of infection in wounds or education of health professionals to prepare them for the realities of clinical practice
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'Open Marxism' against and beyond the 'Great Enclosure'? Reflections on How (Not) to Crack Capitalism
The main purpose of this article is to provide an in-depth discussion of John Hollowayâs recent book, Crack Capitalism. To this end, the paper offers a detailed account of the key strengths and weaknesses of Hollowayâs version of âopen Marxismâ. The analysis is divided into two parts. The first part focuses on six significant strengths of Crack Capitalism: (1) its insistence upon the importance of autonomous forms of agenda-setting for both individual and collective emancipation; (2) its emphasis on the ordinary constitution of social struggles; (3) its fine-grained interpretation of the socio-ontological conditions underlying human agency; (4) its processual conception of radical social transformation; (5) its recognition of the elastic, adaptable, and integrative power of capitalism; and (6) its proposal for an alternative critical theory, commonly known as âopen Marxismâ or âautonomous Marxismâ. The second part of the study examines the principal weaknesses of Crack Capitalism: (1) the counterproductive implications of the preponderance of negativity, owing to a one-sided concern with critique, cracks, and crises; (2) conceptual vagueness; (3) an overuse of poetic and metaphorical language; (4) the absence of a serious engagement with the question of normativity; (5) a lack of substantive evidence; (6) a residual economic reductionism; (7) a simplistic notion of gender; (8) the continuing presence of various problematic âismsâ; (9) the misleading distinction between âdoingâ and âlabourâ; (10) a reductive understanding of capitalism; (11) an unrealistic view of society; and (12) socio-ontological idealis
"Driven to distraction?" Children's experiences of car travel
This is an Author's Accepted Manuscript of an article published in volume, 4, issue 1, pages 59-76 in Mobilities 2009. Copyright @ 2009 Taylor & Francis, available online at: http://www.tandfonline.com/doi/abs/10.1080/17450100802657962.Cars have become increasingly significant features in the lives of many children and adults in the UK and elsewhere. Whilst there is a growing body of research considering how adults experience automobility, that is the increasingly central role of cars within societies, there has been little equivalent research exploring children's perspectives. Drawing upon a variety of methods including personal diaries, photographs, inâdepth interviews and surveys amongst schools within Buckinghamshire and North London, the paper contributes to filling this gap in existing research through exploring how cars are not only journey spaces for children, but are also sites for play, relaxation, homework, companionship, technology and the consumption of commodities. Using a Foucauldian analysis of power, insights into wider familial processes relating to mobility are provided by exploring how cars are sites of conflicting power relations between parents and children. The paper also explores how children's everyday experiences of cars were framed by wider sets of power relations, including car corporations which design and manufacture these spaces, and the role of capital which commodifies everyday activities in cars. In doing so, the paper challenges existing research on automobility for only focusing upon adults' experiences of cars and begins to theorise a more inclusive account of automobility which incorporates children and young people
The Origin of X-shaped Radio Galaxies: Clues from the Z-symmetric Secondary Lobes
Existing radio images of a few X-shaped radio galaxies reveal Z-symmetric
morphologies in their weaker secondary lobes which cannot be naturally
explained by either the galactic merger or radio-lobe backflow scenarios, the
two dominant models for these X-shaped radio sources. We show that the merger
picture can explain these morphologies provided one takes into account that,
prior to the coalescence of their supermassive black holes, the smaller galaxy
releases significant amounts of gas into the ISM of the dominant active galaxy.
This rotating gas, whose angular momentum axis will typically not be aligned
with the original jets, is likely to provide sufficient ram pressure at a
distance ~10 kpc from the nucleus to bend the extant jets emerging from the
central engine, thus producing a Z-symmetry in the pair of radio lobes. Once
the two black holes have coalesced some 10^7 yr later, a rapid reorientation of
the jets along a direction close to that of the orbital angular momentum of the
swallowed galaxy relative to the primary galaxy would create the younger
primary lobes of the X-shaped radio galaxy. This picture naturally explains why
such sources typically have powers close to the FR I/II break. We suggest that
purely Z-symmetric radio sources are often en route to coalescence and the
concomitant emission of substantial gravitational radiation, while X-shaped
ones have already merged and radiated.Comment: 12 pages, 1 compressed figure; accepted for publication in ApJ
Letter
Earth Radiation Budget Experiment (ERBE) scanner instrument anomaly investigation
The results of an ad-hoc committee investigation of in-Earth orbit operational anomalies noted on two identical Earth Radiation Budget Experiment (ERBE) Scanner instruments on two different spacecraft busses is presented. The anomalies are attributed to the bearings and the lubrication scheme for the bearings. A detailed discussion of the pertinent instrument operations, the approach of the investigation team and the current status of the instruments now in Earth orbit is included. The team considered operational changes for these instruments, rework possibilities for the one instrument which is waiting to be launched, and preferable lubrication considerations for specific space operational requirements similar to those for the ERBE scanner bearings
Diffusive counter dispersion of mass in bubbly media
We consider a liquid bearing gas bubbles in a porous medium. When gas bubbles
are immovably trapped in a porous matrix by surface-tension forces, the
dominant mechanism of transfer of gas mass becomes the diffusion of gas
molecules through the liquid. Essentially, the gas solution is in local
thermodynamic equilibrium with vapor phase all over the system, i.e., the
solute concentration equals the solubility. When temperature and/or pressure
gradients are applied, diffusion fluxes appear and these fluxes are faithfully
determined by the temperature and pressure fields, not by the local solute
concentration, which is enslaved by the former. We derive the equations
governing such systems, accounting for thermodiffusion and gravitational
segregation effects which are shown not to be neglected for geological
systems---marine sediments, terrestrial aquifers, etc. The results are applied
for the treatment of non-high-pressure systems and real geological systems
bearing methane or carbon dioxide, where we find a potential possibility of the
formation of gaseous horizons deep below a porous medium surface. The reported
effects are of particular importance for natural methane hydrate deposits and
the problem of burial of industrial production of carbon dioxide in deep
aquifers.Comment: 10 pages, 5 figures, 1 table, Physical Review
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