458 research outputs found

    Wee Whizz Bang: Englishness and Noise in Ford Madox Ford\u27s Parade\u27s End

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    This paper explores representations of Englishness in Ford Madox Ford\u27s Parade\u27s End, identifying in particular a taciturn, monoglossic form of pre-Great War Englishness that is threatened by the cacophonous, heteroglossic post-War world. Through close formal analysis of noise in Ford\u27s tetralogy, framed by an historicist reading of the socio-political contexts of the First World War, this paper demonstrates how Parade\u27s End simultaneously elegises a stiff-upper-lip Englishness while marking such reticence as an obsolete mode of thinking that is incompatible with modernity. In contrast to criticism that identifies The Last Post, the final novel in the tetralogy, as a return to or rebirth of a true form of Englishness, this paper argues that Englishness continues to be problematized at the tetralogy\u27s close. Ford\u27s work reveals an Englishness irrevocably infiltrated by the noise of modernity; pre-War Englishness becomes a fantasy, idealized but unsustainable. By analyzing Ford\u27s representations of Englishness, this paper gives insight into how national identity is mythologized, constructed, and restructured during moments of historical crisis

    Hydrodynamics of Nematic Liquid Crystals for Diffractive Optical Elements

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    Nematic Liquid Crystals (NLCs) are used widely as adaptive optical materials in devices such as lenses, beam steerers and displays. Usually in NLC Diffractive Optical Elements (DOEs), limitations exist in one or more essential parameters, such as diffraction angle, diffraction intensity, aperture size or adaptive behaviour. This thesis will investigate an unusual method to create NLC DOEs, through inducing hydrodynamic flow within the materials. Here, several techniques are used to induce periodic flow patterns within the materials, which result in periodic changes to the device’s optical properties. These periodic structures are evaluated for potential as adaptive optical components. Fraunhofer diffraction theory is introduced as a means to evaluate the potential of various DOEs theoretically. Details of a computer programme developed during the project is presented, which allows calculation of Fraunhofer diffraction patterns. This programme is used to provide quantified analysis of losses in diffraction efficiency caused by imperfect or non-optimized DOEs. The application of these results may be used in aiding DOE device design, which will be discussed. The first method used to create hydrodynamic domains uses a low frequency electric field applied across the NLC. This induces periodic ion flow within the material, leading to the NLCs adopting a state of electrohydrodynamic instability (EHDI). Of several EHDI modes identified, the 1D Normal Roll (NR) mode was most promising as a DOE. The periods of these gratings are strongly dependent upon device spacing (d). In all calamitic materials, the grating period continuously varied from d to as electric field frequency was increased. This lead to a simultaneous decrease in diffraction efficiency. Elastic constant dependency on EHDI is also investigated, where a material of low k33 is created using a bent dimeric mixture. This displays a desirable property of lower grating period by a factor of around 1.5. The second method of creating hydrodynamic patterns in NLCs uses bulk and surface acoustic waves. Acoustic wave transmission in bulk NLCs is discussed. Techniques of measuring the speed of sound (vs) in fluids are given, which are used to obtain a value for vs in the NLC mixture E7 of 1720±70ms-1 at ambient temperatures. NLC structural changes under acoustic fields are examined. These investigations are used to create a novel device where the surface acoustic wavelength was varied using a chirped electrode structure. This created a hydrodynamic grating of continuously variable pitch from 100 ÎŒm to 450 ÎŒm using frequency modulation The findings and performance of the hydrodynamic gratings investigated are evaluated in the context of currently available DOE technologies. Possible further device improvements and theoretical limits using the results from Fraunhofer diffraction modelling are discusse

    Assessing and Teaching Critical Thinking in Communication Science and Disorders

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    Critical thinking is considered to be an important aspect in the training of communication science and disorders students. This paper provides information on the definition, assessment, and teaching of critical thinking. Important critical thinking skills and dispositions include challenging assumptions underlying statements, recognizing the effect of context on perceptions, understandings, and interpretations of the world, developing alternative explanations for observed data they observe, and exhibiting reflective skepticism. Increasing these skills and dispositions help a student develop into a skilled clinician. Assessing students’ clinical thinking skills can be done with tests of general skills, but these often lack validity and reliability. Assessments also can test content or discipline specific thinking skills. Teaching critical skills and dispositions has been done in stand-alone courses and as material embedded within other courses. Within the courses, techniques such as problem-based learning, team-based learning, and case presentations have been effective with mind and concept mapping as tools to visualize how the students think about the material

    The origin of the infrared emission in radio galaxies. III. Analysis of 3CRR objects

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    We present Spitzer photometric data for a complete sample of 19 low redshift (z<0.1) 3CRR radio galaxies as part of our efforts to understand the origin of the prodigious mid- to far-infrared (MFIR) emission from radio-loud AGN. Our results show a correlation between AGN power (indicated by [OIII] 5007 emission line luminosity) and 24 micron luminosity. This result is consistent with the 24 micron thermal emission originating from warm dust heated directly by AGN illumination. Applying the same correlation test for 70 micron luminosity against [OIII] luminosity we find this relation to suffer from increased scatter compared to that of 24 micron. In line with our results for the higher-radio-frequency-selected 2Jy sample, we are able to show that much of this increased scatter is due to heating by starbursts which boost the far-infrared emission at 70 micron in a minority of objects (17-35%). Overall this study supports previous work indicating AGN illumination as the dominant heating mechanism for MFIR emitting dust in the majority of low to intermediate redshift radio galaxies (0.03<z<0.7), with the advantage of strong statistical evidence. However, we find evidence that the low redshift broad-line objects (z<0.1) are distinct in terms of their positions on the MFIR vs. [OIII] correlations.Comment: 31 pages, 3 figures, accepted for publication to Ap

    Full polarization study of SiO masers at 86 GHz

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    We study the polarization of the SiO maser emission in a representative sample of evolved stars in order to derive an estimate of the strength of the magnetic field, and thus determine the influence of this magnetic field on evolved stars. We made simultaneous spectroscopic measurements of the 4 Stokes parameters, from which we derived the circular and linear polarization levels. The observations were made with the IF polarimeter installed at the IRAM 30m telescope. A discussion of the existing SiO maser models is developed in the light of our observations. Under the Zeeman splitting hypothesis, we derive an estimate of the strength of the magnetic field. The averaged magnetic field varies between 0 and 20 Gauss, with a mean value of 3.5 Gauss, and follows a 1/r law throughout the circumstellar envelope. As a consequence, the magnetic field may play the role of a shaping, or perhaps collimating agent of the circumstellar envelopes in evolved objects.Comment: 22 pages, accepted in A&A (19/12/2005

    Stability of palm oil-based emulsion liquid membrane for succinic acid extraction from aqueous solution

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    Emulsion liquid membrane (ELM) process has high potential in the separation of succinic from the fermentation broth. However, the major drawback of this technology is the stability of emulsion globules during the extraction process and the chemical involve d in the liquid membrane formulation. This study investigate the stability of ELM using a greener formulation containing Amberlite LA - 2 as a carrier, Span 80 and Tween 80 as a surfactant, palm oil as a diluent and sodium carbonate (Na 2 CO 3 ) as an aqueous st ripping agent. The emulsion stability was evaluated by observing the water - oil separation of the emulsion and microscopic image of emulsion droplets count and size. Several operating parameters including the organic to internal ratio, homogenizer speed, ho mogenizing time, and surfactant concentration, and surfactant blend were investigated. The results show the most stable water - in - oil emulsion was observed at 3:1 organic to internal ratio; 7000rpm homogenizer speed; 5 minute emulsification time; 3% (w/v) s urfactant at HLB 8. Besides, the extraction study shows 70% of the succinic acid was extracted at 0.01M Na 2 CO 3 , 1:3 treat ratio, and 0.7M Amberlite in palm oil at optimum primary emulsion stability conditions. This indicates the potential of using palm oil based ELM for the extraction of succinic acid

    Structure of laponite-styrene precursor dispersions for production of advanced polymer-clay nanocomposites

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    One method for production of polymer-clay nanocomposites involves dispersal of surface-modified clay in a polymerisable monomeric solvent, followed by fast in situ polymerisation. In order to tailor the properties of the final material we aim to control the dispersion state of the clay in the precursor solvent. Here, we study dispersions of surface-modified Laponite, a synthetic clay, in styrene via large-scale Monte-Carlo simulations and experimentally, using small angle X-ray and static light scattering. By tuning the effective interaction between simulated laponite particles we are able to reproduce the experimental scattering intensity patterns for this system, with good accuracy over a wide range of length scales. However, this agreement could only be obtained by introducing a permanent electrostatic dipole moment into the plane of each Laponite particle, which we explain in terms of the distribution of substituted metal atoms within each Laponite particle. This suggests that Laponite dispersions, and perhaps other clay suspensions, should display some of the structural characteristics of dipolar fluids. Our simulated structures show aggregation regimes ranging from networks of long chains to dense clusters of Laponite particles, and we also obtain some intriguing ‘globular’ clusters, similar to capsids. We see no indication of any ‘house-of-cards’ structures. The simulation that most closely matches experimental results indicates that gel-like networks are obtained in Laponite dispersions, which however appear optically clear and non-sedimenting over extended periods of time. This suggests it could be difficult to obtain truly isotropic equilibrium dispersion as a starting point for synthesis of advanced polymer-clay nanocomposites with controlled structures

    Spatially Resolved Observations of the Galactic Center Source, IRS 21

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    We present diffraction-limited 2-25 micron images obtained with the W. M. Keck 10-m telescopes that spatially resolve the cool source, IRS 21, one of a small group of enigmatic objects in the central parsec of our Galaxy that have eluded classification. Modeled as a Gaussian, the azimuthally-averaged intensity profile of IRS 21 has a half-width half-maximum (HWHM) size of 650+/-80 AU at 2.2 microns and an average HWHM size of 1600+/-200 AU at mid-infrared wavelengths. These large apparent sizes imply an extended distribution of dust. The mid-infrared color map indicates that IRS 21 is a self-luminous source rather than an externally heated dust clump as originally suggested. The spectral energy distribution has distinct near- and mid-infrared components. A simple radiative transfer code, which simultaneously fits the near- and mid- infrared photometry and intensity profiles, supports a model in which the near-infrared radiation is scattered and extincted light from an embedded central source, while the mid-infrared emission is from thermally re-radiating silicate dust. We argue that IRS 21 (and by analogy the other luminous sources along the Northern Arm) is a massive star experiencing rapid mass loss and plowing through the Northern Arm, thereby generating a bow shock, which is spatially resolved in our observations.Comment: 29 pages, 8 figures, Latex. Astrophysical Journal, accepte

    The Distance and Size of the Red Hypergiant NML Cyg from VLBA and VLA Astrometry

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    We have measured the annual parallax and proper motion of NML Cyg from multiple epoch VLBA observations of the circulstellar H2O and SiO masers. The measured parallax of NML Cyg is 0.620+/-0.047 mas, corresponding to a distance of 1.61+/-0.12 kpc. The measured proper motion of NML Cyg is mu_x = -1.55+/-0.42 mas/yr eastward and mu_y= -4.59+/-0.41 mas/yr northward. Both Both the distance and proper motion are consistent with that of Cyg OB2, within their joint uncertainty, confirming their association. Taking into consideration molecular absorption signatures seen toward NML Cyg, we suggest that NML Cyg lies on the far side of the Cyg OB2 association. The stellar luminosity revised with our distance brings NML Cyg significantly below the empirical luminosity limit for a red supergiant. Using the VLA observation the radio photosphere and the SiO maser as a phase reference, we partially resolve the radio photosphere of NML Cyg at 43 GHz and find its diameter is about 44 mas, suggesting an optical stellar diameter of 22 mas, if the size of radio photosphere is 2 times the optical photosphere. Based on the position of circumstellar SiO masers relative to the radio photosphere, we estimate the absolute position of NML Cyg at epoch 2008.868 to be R.A. = 20h46m25.5382s +/- 0.0010s, Decl. = 40d06'59.379" +/- 0.015". The peculiar motions of NML Cyg, the average of stars in Cyg OB2, and four other star-forming regions rules out that an expanding "Stroemgren sphere" centered on Cyg OB2 is responsible for the kinematics of the Cygnus X region.Comment: 15 pages, 11 figures, accepted by A&
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