2,737 research outputs found
Lorenz B. Graham, circa 1921/1930
No full textPhotograph of author Lorenz B. Graham. Graham wrote children's books. His sister, Shirley Graham, was married to civil rights leader W.E.B. DuBois
Graham Greene An Approach to the Novels
No full textThis study reveals Greene in a dual role as author, one who projects literary experience into his view of life and subsequently projects both his experience and its "literary" interpretation into his fiction; and it defines two phases of Greenes novels through the changing relationship between writer and protagonists. The first phase progresses from acutely sensitive, self-divided young men somewhat like the young Greene to embittered, alienated characters ostensibly at great distance from their creator. The second phase (1939) includes a series of "portraits of the artist" through which Greene confronts more directly the tensions and conflicts of his private life.Book Cover -- Half-Title -- Title -- Copyright -- Dedication -- Contents -- Introduction -- Acknowledgements -- GRAHAM GREENE -- CHAPTER ONE Protagonists of the First Phase -- YOUTH -- DIVIDED SELVES -- WOMEN AND REDEMPTION -- MARRIAGE IN THE FIRST PHASE -- THE LITERARY FRAME -- THE FIRST-PHASE PROTAGONIST AND THE AUTHOR -- CHAPTER TWO Letters and Diaries -- LETTERS TO VIVIEN -- DIARIES -- CHAPTER THREE A Gun for Sale -- A GUN FOR SALE AND BROWNING'S "CHILDE ROLAND" -- A GUN FOR SALE AND TENNYSON'S MAUD -- CHAPTER FOUR Brighton Rock -- PINKIE AS NAPOLEONIC STRATEGIST -- CHARACTERS AND NAMES -- BRIGHTON ROCK AS A FAUSTIAN NOVEL -- CHAPTER FIVE Protagonists of the Second Phase -- AGE -- CHILDREN AND CHILDHOOD -- SELF-DIVISION -- MARRIAGE IN THE SECOND PHASE -- CHAPTER SIX The Strategy of Allusion in the Second Phase -- TOWARD THE WRITER AS PROTAGONIST -- CHAPTER SEVEN Portraits of the Artist -- CHAPTER EIGHT Travels with My Aunt -- CHAPTER NINE The Honorary Consul -- CHAPTER TEN The Human Factor -- CHAPTER ELEVEN Dr. Fischer of Geneva -- CHAPTER TWELVE Monsignor Quixote -- POSTSCRIPT: "YOUR DREAM HAS BEEN YOUR LIFE. -- CHAPTER THIRTEEN The Captain and the Enemy -- FINIS -- Selected Bibliography -- (A) WORKS BY GRAHAM GREENE -- (B) CRITICAL AND BIOGRAPHICAL WORKS -- Index -- Permissions Acknowledgements -- PENGUIN PUTNAM INC. -- SIMON & -- SCHUSTERThis study reveals Greene in a dual role as author, one who projects literary experience into his view of life and subsequently projects both his experience and its "literary" interpretation into his fiction; and it defines two phases of Greenes novels through the changing relationship between writer and protagonists. The first phase progresses from acutely sensitive, self-divided young men somewhat like the young Greene to embittered, alienated characters ostensibly at great distance from their creator. The second phase (1939) includes a series of "portraits of the artist" through which Greene confronts more directly the tensions and conflicts of his private life.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Ageing, Motion Perception and the Compensation for Eye Movements
No full textSmooth pursuit over a textured background introduces full-field motion to the retinal image in the direction opposing the eye movement. If this motion is not correctly attributed to the eye movement, it can be falsely perceived as motion in the world (Haarmeier, Thier, Repnow & Petersen, 1997). In order to correctly attribute retinal motion, the visual system must compensate for the effects of eye movements on the retinal image in motion perception. Visual motion perception is important for safely navigating the environment and has been linked to difficulties experienced by older adults while driving (Conlon & Herkes, 2008; Raghuram & Lakshminarayanan, 2006) and walking (Cavanaugh, 2002). The experiments reported in this thesis were devised in order to examine the effects of ageing on the perception of illusory motion during eye movements and therefore on the ability to compensate for eye movements in motion perception. The perception of motion during smooth pursuit eye movements was assessed in adults ranging in age from 17 to 79 years. The computer based task required participants to respond to the speed and direction of motion of a large-field random dot pattern while following a moving target dot with the eyes. For this task, a magnitude estimation tool was especially designed based on the direction response method of Bennett, Sekuler and Sekuler (2007). During the experimental session an eye tracker recorded the participant's eye movements. For the purposes of analysis, four groups were defined by age. It was found that the smooth pursuit of adults from ~40 years of age was slower than that of the younger age groups. With stationary eyes, the oldest age group ranging in age from 60 to 79 years tended to overestimate the speed of the dot pattern as compared to younger observers. This tendency decreased at higher background speeds. Eye movements appeared to affect the perception of the dot field's motion more in the group of participants ranging in age from 40 to 54 years than in the younger age groups. This also seemed to be the case for participants aged over 60 when viewing horizontal motion but not vertical motion. The results of this study suggest that older observers may be less able to compensate for the effects of eye movements on the retinal image. This could potentially affect their ability to safely and confidently navigate the environment
Modelling and reconstructing the respiratory motion of the liver
No full textRespiratory organ motion is a complicating factor in tumour treatment. For dose delivery, the aim is to obtain a possibly static target in the beam's eye view whenever the beam is on. Such a reduction of motion allows for reducing the safety margins or for delivering a higher dose in a shorter time. This thesis proposes a statistical, population-based model that covers all modes of deformation such as the perpetual breathing motion and organ drift. It furthermore provides a mathematical tool to estimate the current organ position based on sparse and low-dimensional measurements, with the goal to use ultrasound for obtaining the respiratory signal directly from the liver. The model can describe complex variations of the liver in shape and position without knowing the underlying physical mechanisms. To achieve this, 4D-MRI is acquired for a number of subjects. From these images, deformation fields are extracted, inter-subject correspondence is established and the model is learned from the data. The prediction accuracy is evaluated in various simulations where partial information of the organ in 3d, 2d or only 1d is known. Furthermore, an experiment is described where simultaneous 4D-MRI and ultrasound is acquired for six subjects in order to evaluate the approach in a clinically relevant scenario. The prediction is driven by tracked points in the ultrasound images and then compared to the ground-truth obtained from 4D-MRI. The results show that a statistical motion model can significantly reduce the uncertainty with respect to organ position during respiration
Individual Particle Motion in Colloids: Microviscosity, Microdiffusivity, and Normal Stresses
No full textColloidal dispersions play an important role in nearly every aspect of life, from paint to biofuels to nano-therapeutics. In the study of these so-called complex fluids, a connection is sought between macroscopic material properties and the micromechanics of the suspended particles. Such properties include viscosity, diffusivity, and the osmotic pressure, for example. But many such systems are themselves only microns in size overall; recent years have thus seen a dramatic growth in demand for exploring microscale systems at a much smaller length scale than can be probed with conventional macroscopic techniques. Microrheology is one approach to such microscale interrogation, in which a Brownian “probe” particle is driven through a complex fluid, and its motion tracked in order to infer the mechanical properties of the embedding material. With no external forcing the probe and background particles form an equilibrium microstructure that fluctuates thermally with the solvent. Probe motion through the dispersion distorts the microstructure; the character of this deformation, and hence its influence on probe motion, depends on the strength with which the probe is forced, F ext , compared to thermal forces, kT/b, defining a P´eclet number, P e = F ext /(kT /b), where kT is the thermal energy and b the bath-particle size. Both the mean and the fluctuating motion of the probe are of interest. Recent studies showed that the reduction in mean probe speed gives the effective material viscosity. But the velocity of the probe also fluctuates due to collisions with the suspended particles, causing the probe to undergo a random walk process. It is shown that the long-time mean-square fluctuational motion of the probe is diffusive and the effective diffusivity of the forced probe is determined for the full range of P´eclet number. At small Pe Brownian motion dominates and the diffusive behavior of the probe characteristic of passive microrheology is recovered, but with an incremental flow-induced “micro-diffusivity” that scales as Dmicro ∼ Da P e 2 φb , where viii φb is the volume fraction of bath particles and Da is the self-diffusivity of an isolated probe. At the other extreme of high P´eclet number the fuctuational motion is still diffusive, and the diffusivity becomes primarily force-induced , scaling as (F ext /η)φb , where η is the viscosity of the solvent. The force-induced “microdiffusivity” is anisotropic, with diffusion longitudinal to the direction of forcing larger in both limits compared to transverse diffusion, but more strongly so in the high-P e limit.
Previous work in microrheology defined a scalar viscosity; however, a tensorial expression for the suspension stress in microrheology was still lacking. The notion that diffusive flux is driven by gradients in particle-phase stress leads to the idea that the microdiffusivity can be related directly to the suspension stress. In consequence, the anisotropy of the diffusion tensor may reflect the presence of normal stress differences in non-linear microrheology. While the particle-phase stress tensor can be determined as the second moment of the deformed microstructure, in this study a connection is made between diffusion and stress gradients, and an analytical expression for particle-phase stress as a function of the microdiffusivity and microviscosity is obtained. The two approaches agree, suggesting that normal stresses and normal stress differences can be measured in active microrheological experiments if both the mean and mean-square motion of the probe are monitored. Owing to the axisymmetry of the motion about a spherical probe, the second normal stress difference is zero, while the first normal stress difference is linear in P e for P e ≫ 1 and vanishes as P e 3 for P e ≪ 1. An additional important outcome is that the analytical expression obtained for stress-induced migration can be viewed as a generalized non-equilibrium Stokes-Einstein relation.
Studies of steady-state dispersion behavior reveal the hydrodynamic and microstructural mechanisms that underlie non-Newtonian behaviors (e.g. shear-thinning, shear-thickening, and normal stress differences). But an understanding of how the microstructures evolve from the equilibrium state, and how non-equilibrium properties develop in time is much less well understood. Transient suspension behavior in the near-equilibrium, linear response regime has been studied via its connection to low-amplitude oscillatory probe forcing and the complex modulus; at very weak forcing, the microstructural response that drives viscosity is indistinguishable from equilibrium fluctuations. But important information about the basic physical aspects of structural development and relaxation ix in a medium are captured by start-up and cessation of the imposed deformation in the non-linear regime, where the structure is driven far from equilibrium. Here we study the evolution of stress and microstructure in a colloidal dispersion by tracking transient probe motion during start-up and cessation of a strong flow. For large P e, steady state is reached when a boundary layer (in which advection balances diffusion) forms at particle contact on the timescale of the flow, a/U , where a is the probe size and U its speed. On the other hand, relaxation following cessation occurs over several timescales corresponding to distinct physical processes. For very short times, the timescale for relaxation is set by the diffusion over the boundary-layer thickness. Nearly all stress relaxation occurs during this process, owing to the dependence of the bath-particle drag on the contact value of the microstructure. At longer times the collective diffusion of the bath particles acts to close the wake. In this long-time limit as structural isotropy is restored, the majority of the microstructural relaxation occurs with very little change in suspension stress. Theoretical results are presented and compared with Brownian dynamics simulation. Two regimes of probe motion are studied: an externally applied constant force and an imposed constant velocity. The microstructural evolution is qualitatively different for the two regimes, with a longer transient phase and a thinner boundary layer and longer wake at steady state in the latter case. The work is also compared to analogous results for sheared suspensions undergoing start-up and cessation.
The study moves next to investigations of dual-probe microrheology. Motivated by the phenomenon of equilibrium depletion interactions, we study the interaction between a pair of probe particles translating with equal velocity through a dispersion with their line of centers transverse to the external forcing. The character of the microstructure surrounding the probes is determined both by the distance R by which the two probes are separated and by the strength of the external forcing, P e = U a/Db , where U is the constant probe velocity and Db the diffusivity of the bath particles. Osmotic pressure gradients develop as the microstructure is deformed, giving rise to an interactive force between the probes. This force is studied for a range of P e and R. For all separations R > 2a, the probes attract when P e is small. As the strength of the forcing increases, a qualitative change in the interactive force occurs: the probes repel each other. The probe separation R at which the x attraction-to-repulsion transition occurs decreases as P e increases, because the entropic depletion attraction becomes weak compared to the force-induced osmotic repulsion. The non-equilibrium interactive force is strictly repulsive for two separated probes.
But non-linear microrheology provides far more than a microscale technique for interrogating complex fluids. In 1906, Einstein published the famous thought experiment in which he proposed that if a liquid were indeed composed of atoms, then the motion of a small particle suspended in the fluid would move with the same random trajectories as the solvent atoms. Combining the theories of kinetics, diffusion, and thermodynamics, he showed that the diffusive motion of a small particle is indeed evidence of the existence of the atom. Perrin confirmed the theory with measurement in 1909. This is a profound conclusion, drawn by simply watching a particle move in a liquid. Here, we follow this example and watch a particle move in a complex fluid—but now for a system that is not at equilibrium. In equilibrium systems, the relationship between fluctuation and dissipation is fundamental to our understanding of colloid physics. By studying fluctuations away from equilibrium, we have discovered an analogous non-equilibrium relation between fluctuation and dissipation—and that the balance between the two is stored in the material stress. A final connection can be made between this stress and energy storage.</p
Anthony McCall: Notebooks and Conversations
No full textCharting the development of the studio practice of New York based artist Anthony McCall (b.1946), this publication features facsimile reproductions of pages from McCall's extensive archive of notebooks, which are supported by production scores and installation photographs. It was formed out of a series of discussions that took place over the last decade between McCall and the artists Graham Ellard and Stephen Johnstone.
Anthony McCall is known for his ‘solid-light’ installations, a series that he began in 1973 with his seminal Line Describing a Cone, in which a volumetric form composed of projected light slowly evolves in three-dimensional space. Since creating this ground-breaking piece, McCall has had work exhibited at museums and galleries throughout the world, including the Museum of Modern Art, New York; Tate; Whitney Museum of American Art; Serpentine Gallery; Centre Pompidou; Moderna Museet, Stockholm and Hamburger Bahnhof, Berlin.
Examining McCall's work of the 1970s and the pieces developed since his return to making art in 2003, the conversations explore McCall's over-riding preoccupations as an artist whose work occupies a space between sculpture, cinema and drawing. In doing so, the book also narrates how McCall has transformed the way he understands his own practice, particularly in relation to notions of performance, the body, projected installation, durational structure and spectatorship.
Emphasising both the continuities and shifts in McCall's working methods in the studio over the last 40 years, Anthony McCall: Notebooks and Conversations presents unique insights into his extraordinary body of work.Contents: Introduction: Thinking in notebook form, Graham Ellard and Stephen Johnstone; Conversations - Tate Britain, London;10 September 2004; Centre Georges Pompidou, La Maison Rouge, Paris; 5 October 2004; Anthony McCall Studio, New York; 3 March 2005; Ellard and Johnstone Studio, London; 25 March 2006; Ellard and Johnstone Studio, London; 20 March 2011; Gallerie Martine Aboucaya, Paris; 22 October 2013; Flims; Performances; Slide works; Chronological list of notebooks; Biographies.About the Author: Graham Ellard and Stephen Johnstone have collaborated since 1993. Their large-scale video installations and 16mm films, concerned with the parallels between film and architecture, have been exhibited in galleries and museums internationally, including Tate Liverpool; Museum of Contemporary Art, Sydney; Centre Pompidou; the Internationale Kurzfilmtage Oberhausen; The Aichi Triennale, Nagoya and Tate Britain. Graham Ellard is Professor of Fine Art at Central Saint Martins, University of the Arts London. Stephen Johnstone is Professor of Fine Art at Goldsmiths, University of London.Reviews: 'The handsome volume Anthony McCall: Notebooks and Conversations ... is the kind of book that will increase in importance to students of art and art history over time ... it is the kind of invaluable document that will help us access his [McCall's] artworks in their own terms far into the future.' Jarrett Earnest, The Brooklyn Rail
'...this compendium offers readers a fascinating insight into the working methods and thought processes of this groundbreaking British artist...Illuminating.' StateF22Co-publisher: Published by Lund Humphries in association with Kunstmuseum St Gallen, Switzerlan
Facial motion perception in autism spectrum disorder and neurotypical controls
No full textThis thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University LondonFacial motion provides an abundance of information necessary for mediating social communication. Emotional expressions, head rotations and eye-gaze patterns allow us to extract categorical and qualitative information from others (Blake & Shiffrar, 2007). Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterised by a severe impairment in social cognition. One of the causes may be related to a fundamental deficit in perceiving human movement (Herrington et al., (2007). This hypothesis was investigated more closely within the current thesis. In neurotypical controls, the visual processing of facial motion was analysed via EEG alpha waves. Participants were tested on their ability to discriminate between successive animations (exhibiting rigid and nonrigid motion). The appearance of the stimuli remained constant over trials, meaning decisions were based solely on differential movement patterns. The parieto-occipital region was specifically selective to upright facial motion while the occipital cortex responded similarly to natural and manipulated faces. Over both regions, a distinct pattern of activity in response to upright faces was characterised by a transient decrease and subsequent increase in neural processing (Girges et al., 2014). These results were further supported by an fMRI study which showed sensitivity of the superior temporal sulcus (STS) to perceived facial movements relative to inanimate and animate stimuli. The ability to process information from dynamic faces was assessed in ASD. Participants were asked to recognise different sequences, unfamiliar identities and genders from facial motion captures. Stimuli were presented upright and inverted in order to assess configural processing. Relative to the controls, participants with ASD were significantly impaired on all three tasks and failed to show an inversion effect (O'Brien et al., 2014). Functional neuroimaging revealed atypical activities in the visual cortex, STS and fronto-parietal regions thought to contain mirror neurons in participants with ASD. These results point to a deficit in the visual processing of facial motion, which in turn may partly cause social communicative impairments in ASD
Mechanics of inhomogeneous turbulence and interfacial layers
No full textThe mechanics of inhomogeneous turbulence in and adjacent to interfacial layers bounding turbulent and non-turbulent regions are analysed. Different mechanisms are identified according to the straining by the turbulent eddies in relation to the strength of the mean shear adjacent to, or across, the interfacial layer. How the turbulence is initiated and the topology of the region of turbulence are also significant factors. Specifically the cases of a layer of turbulence bounded on one, or two, sides by a uniform and/or shearing flow, and a circular region of a rotating turbulent vortex are considered and discussed.
The entrainment processes at fluctuating interfaces occur both at the outer edges of turbulent shear layers, with and without free-stream turbulence (e.g. jets, wakes and boundary layers), at internal boundaries such as those at the outside of the non-turbulent core of swirling flows (e.g. the ‘eye-wall’ of a hurricane) or at the top of the viscous sublayer and roughness elements in turbulent boundary layers. Conditionally sampled data enables these concepts to be tested. These concepts lead to physically based estimates for critical modelling parameters such as eddy viscosity near interfaces, entrainment rates, maximum velocity and displacement heights
The DSM diagnostic criteria for Female Sexual Arousal Disorder
No full textThis article reviews and critiques the DSM-IV-TR diagnostic criteria for Female Sexual Arousal Disorder (FSAD). An overview of how the diagnostic criteria for FSAD have evolved over previous editions of the DSM is presented and research on prevalence and etiology of FSAD is briefly reviewed. Problems with the essential feature of the DSM-IV-TR diagnosis — “an inability to attain, or to maintain…an adequate lubrication-swelling response of sexual excitement” — are identified. The significant overlap between “arousal” and “desire” disorders is highlighted. Finally, specific recommendations for revision of the criteria for DSM-V are made, including use of a polythetic approach to the diagnosis and the addition of duration and severity criteria
Numerical simulation of flow past a cylinder in orbital motion
No full textA finite difference solution is presented for 2D laminar unsteady flow around a circular cylinder in orbital motion placed in a uniform flow for Re = 130, 160, and 180. Four
cases displaying full lock-in are presented. The variation of time-mean and root-mean-square (rms) values of lift and drag coeffcients were investigated against the amplitude of vibration
in transverse direction. Abrupt jumps were found in the time-mean and rms values of lift and rms values of drag. These jumps seem to be caused by a change in the vortex structure
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