30,136 research outputs found

    Statistical Time Series Models of Pilot Control with Applications to Instrument Discrimination

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    A general description of the methodology used in obtaining the transfer function models and verification of model fidelity, frequency domain plots of the modeled transfer functions, numerical results obtained from an analysis of poles and zeroes obtained from z plane to s-plane conversions of the transfer functions, and the results of a study on the sequential introduction of other variables, both exogenous and endogenous into the loop are contained

    The spatial damping of magnetohydrodynamic waves in a flowing partially ionised prominence plasma

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    Solar prominences are partially ionised plasmas displaying flows and oscillations. These oscillations show time and spatial damping and, commonly, have been explained in terms of magnetohydrodynamic (MHD) waves. We study the spatial damping of linear non-adiabatic MHD waves in a flowing partially ionised plasma, having prominence-like physical properties. We consider single fluid equations for a partially ionised hydrogen plasma including in the energy equation optically thin radiation, thermal conduction by electrons and neutrals, and heating. Keeping the frequency real and fixed, we have solved the obtained dispersion relations for the complex wavenumber, k, and have analysed the behaviour of the damping length, wavelength and the ratio of the damping length to the wavelength, versus period, for Alfven, fast, slow and thermal waves.Comment: 28 pages, 9 figure

    'It's a Form of Freedom': The experiences of people with disabilities within equestrian sport

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    This paper explores the embodied, gendered experiences of disabled horse‐riders. Drawing on data from five in‐depth interviews with paradressage riders, the ways in which their involvement in elite disability sport impacts upon their sense of identity and confidence are explored, as well as the considerable health and social benefits that this involvement brings. Social models of disability are employed and the shortcomings of such models, when applied to disability sport, are highlighted. The data presented here demonstrates the necessity of seeing disability sport as an embodied experience and acknowledging the importance of impairment to the experiences of disabled athletes. Living within an impaired body is also a gendered experience and the implications of this when applied to elite disability sport are considered

    Expression of beta human chorionic gonadotrophin by non-trophoblastic non-endocrine 'normal' and malignant epithelial cells.

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    Expression of hCG and its free subunits by non-trophoblastic tumours is well recognised. Previously we reported hCG secretion by normal and malignant bladder epithelial cells in vitro. Here we examined culture medium from 83 different cell lines derived mainly from common epithelial tumours. Thirty-two of the cell lines were found to secrete hCG-like material into their culture media. Partial immunochemical characterisation showed that of these only choriocarcinoma and fetal tissue cell lines produced intact hCG and alpha subunit. The remaining 28 hCG-expressing epithelial cell lines, which are of mucosal origin, only secreted free beta subunit. Expression of free beta hCG by non-trophoblastic nonendocrine cells would appear to be especially characteristic of mucosal epithelia from the genitourinary and oral/respiratory tracts. Furthermore, this phenomenon may be characteristic of epithelium with transitional and/or squamous cell-like properties

    Tricarbonylchlorido(6'7'-dihydro-5’H-spiro[cyclopentane-1,6'-dipyrido-[3,2-d:2',3'-f][1,3]diazepine]-κ2N1,N11)-rhenium(I)

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    In the title compound, [ReCl(C15H16N4)(CO)3], the ReI ion is coordinated in a distorted octahedral geometry by one Cl atom, two N atoms of the bidentate ligand and three carbonyl groups. The cyclopentane group is orientated in a transoid fashion with respect to the chloride ligand. The dihedral angle between the pryridine rings is 10.91 (12)°. In the crystal, N-H...Cl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (001)

    Study on the neuronal circuits implicated in postural tremor and hypokinesia

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    The effect of various tegmentary lesions at the level of the pontomesenchphalon in monkeys on motor function was observed. The importance of the monoaminergic mechanisms of the brainstem is discussed. The results also show the importance of the descending tegmentary rubral system and the rubroolivocerebellar circuit in controlling peripheral motor activity. The destruction of the sensory motor cortex proves to be a more effective way of eliminating spontaneous or harmaline induced tremor than the complete interruption of the pyramidal system on the level of the cerebral peduncle

    Controls on the spatial distribution of oceanic <i>δ</i><sup>13</sup>C<sub>DIC</sub>

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    We describe the design and evaluation of a large ensemble of coupled climate–carbon cycle simulations with the Earth system model of intermediate complexity GENIE. This ensemble has been designed for application to a range of carbon cycle questions, including the causes of late- Quaternary fluctuations in atmospheric CO2. Here we evaluate the ensemble by applying it to a transient experiment over the recent industrial era (1858 to 2008 AD). We employ singular vector decomposition and principal component emulation to investigate the spatial modes of ensemble variability of oceanic dissolved inorganic carbon (DIC) δ13C, considering both the spun-up pre-industrial state and the transient change. These analyses allow us to separate the natural (preindustrial) and anthropogenic controls on the δ13CDIC distribution. We apply the same dimensionally reduced emulation techniques to consider the drivers of the spatial uncertainty in anthropogenic DIC. We show that the sources of uncertainty related to the uptake of anthropogenic δ13CDIC and DIC are quite distinct. Uncertainty in anthropogenic δ13C uptake is controlled by air–sea gas exchange, which explains 63% of modelled variance. This mode of variability is largely absent from the ensemble variability in CO2 uptake, which is rather driven by uncertainties in thermocline ventilation rates. Although the need to account for air–sea gas exchange is well known, these results suggest that, to leading order, uncertainties in the ocean uptake of anthropogenic 13C and CO2 are governed by very different processes. This illustrates the difficulties in reconstructing one from the other, and furthermore highlights the need for careful targeting of both δ13CDIC and DIC observations to better constrain the ocean sink of anthropogenic CO2

    Nonuniqueness in a minimal model for cell motility

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    Two–phase flow models have been used previously to model cell motility, however these have rapidly become very complicated, including many physical processes, and are opaque. Here we demonstrate that even the simplest one–dimensional, two–phase, poroviscous, reactive flow model displays a number of behaviours relevant to cell crawling. We present stability analyses that show that an asymmetric perturbation is required to cause a spatially uniform, stationary strip of cytoplasm to move, which is relevant to cell polarization. Our numerical simulations identify qualitatively distinct families of travelling–wave solution that co–exist at certain parameter values. Within each family, the crawling speed of the strip has a bell–shaped dependence on the adhesion strength. The model captures the experimentally observed behaviour that cells crawl quickest at intermediate adhesion strengths, when the substrate is neither too sticky nor too slippy
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