4,318 research outputs found

    Numerical study on diverging probability density function of flat-top solitons in an extended Korteweg-de Vries equation

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    We consider an extended Korteweg-de Vries (eKdV) equation, the usual Korteweg-de Vries equation with inclusion of an additional cubic nonlinearity. We investigate the statistical behaviour of flat-top solitary waves described by an eKdV equation in the presence of weak dissipative disorder in the linear growth/damping term. With the weak disorder in the system, the amplitude of solitary wave randomly fluctuates during evolution. We demonstrate numerically that the probability density function of a solitary wave parameter κ\kappa which characterizes the soliton amplitude exhibits loglognormal divergence near the maximum possible κ\kappa value.Comment: 8 pages, 4 figure

    Occupy: 'struggles for the common or an 'anti-politics of dignity? Reflections on Hardt and Negri and John Holloway

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    This article provides a critical examination of Michael Hardt and Antonio Negri’s and John Holloway’s theory of revolutionary subjectivity, and does so by applying their theories to the Occupy movement of 2011. Its central argument is that one should avoid collapsing ‘autonomist’ and ‘open’ Marxism, for whilst both approaches share Tronti’s (1979) insistence on the constituent role of class struggle, and also share an emphasis on a prefigurative politics which engages a non-hierarchical and highly participatory politics, there nevertheless remain some significant differences between their approaches. Ultimately, when applied to Occupy Movement whilst their theory isn’t entirely unproblematic, I will argue that Hardt and Negri’s ‘autonomist’ approach offers the stronger interpretation, due mainly to their revised historical materialism

    Earth Radiation Budget Experiment (ERBE) scanner instrument anomaly investigation

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    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

    Highly supersonic motions within the outer features of the Eta Carinae nebulosity

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    Spatially resolved Hα\alpha and [N{\sc ii}] line profiles have been obtained over striking features in the outer regions of the Eta Carinae nebula. The highly irregular outer `shell' of low ionization, [N{\sc ii}] bright, knots has been shown to exhibit radial velocities between -1200 and +300 km/s with respect to the systemic radial velocity, over its perimeter. Furthermore, several knots have been found which appear to emit only in the Hα\alpha line with radial velocities up to -1450 km/s. However, the most intriguing features are a narrow `spike' that projects through this outer shell and a faint `arc' of emission that extends well beyond it. The `spike', which exhibits a change of radial velocity along its length, could be a narrow collimated jet with an outflow velocity of > 1000 km/s. In one interpretation the `arc' is modelled by a conical outflow and mechanisms for generating [N{\sc ii}] emission from highly supersonic gas are also discussed.Comment: MNRAS style file, 6 pages. 7 eps figures are not included but are available individually at http://axp2.ast.man.ac.uk:8000/Preprints.htm

    Validation of a Multivariate Serum Profile for Epithelial Ovarian Cancer Using a Prospective Multi-Site Collection

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    In previous studies we described the use of a retrospective collection of ovarian cancer and benign disease samples, in combination with a large set of multiplexed immunoassays and a multivariate pattern recognition algorithm, to develop an 11-biomarker classification profile that is predictive for the presence of epithelial ovarian cancer. In this study, customized, Luminex-based multiplexed immunoassay kits were GMP-manufactured and the classification profile was refined from 11 to 8 biomarkers (CA-125, epidermal growth factor receptor, CA 19-9, C-reactive protein, tenascin C, apolipoprotein AI, apolipoprotein CIII, and myoglobin). The customized kits and the 8-biomarker profile were then validated in a double-blinded manner using prospective samples collected from women scheduled for surgery, with a gynecologic oncologist, for suspicion of having ovarian cancer. The performance observed in model development held in validation, demonstrating 81.1% sensitivity (95% CI 72.6 – 87.9%) for invasive epithelial ovarian cancer and 85.4% specificity (95% CI 81.1 – 88.9%) for benign ovarian conditions. The specificity for normal healthy women was 95.6% (95% CI 83.6 – 99.2%). These results have encouraged us to undertake a second validation study arm, currently in progress, to examine the performance of the 8-biomarker profile on the population of women not under the surgical care of a gynecologic oncologist

    Si3AlP: A new promising material for solar cell absorber

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    First-principles calculations are performed to study the structural and optoelectronic properties of the newly synthesized nonisovalent and lattice-matched (Si2)0.6(AlP)0.4 alloy [T. Watkins et al., J. Am. Chem. Soc. 2011, 133, 16212.] We find that the ordered CC-Si3AlP with a basic unit of one P atom surrounded by three Si atoms and one Al atom is the most stable one within the experimentally observed unit cell.1 Si3AlP has a larger fundamental band gap and a smaller direct band gap than Si, thus it has much higher absorption in the visible light region. The calculated properties of Si3AlP suggest that it is a promising candidate for improving the performance of the existing Si-based solar cells. The understanding on the stability and band structure engineering obtained in this study is general and can be applied for future study of other nonisovalent and lattice-matched semiconductor alloys
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