Distribution by Scientific Domains
Distribution within Engineering

Kinds of Motion

  • angular motion
  • annulus motion
  • anterior motion
  • artery motion
  • atomic motion
  • body motion
  • brownian motion
  • bulk motion
  • cardiac motion
  • chain motion
  • chaotic motion
  • character motion
  • collective motion
  • cooperative motion
  • cord motion
  • domain motion
  • dynamic motion
  • earthquake motion
  • finger motion
  • fluid motion
  • fractional brownian motion
  • geometric brownian motion
  • ground motion
  • head motion
  • hinge motion
  • input motion
  • internal motion
  • intramolecular motion
  • joint motion
  • large-amplitude motion
  • lateral motion
  • local motion
  • mean motion
  • molecular motion
  • nuclear motion
  • object motion
  • orbital motion
  • oscillatory motion
  • paradoxical septal motion
  • particle motion
  • patient motion
  • peculiar motion
  • physiological motion
  • pitch motion
  • plate motion
  • proper motion
  • radial motion
  • regional wall motion
  • relative motion
  • rigid body motion
  • rotary motion
  • rotational motion
  • segmental motion
  • seismic motion
  • septal motion
  • ship motion
  • side-chain motion
  • sliding motion
  • strong ground motion
  • surface motion
  • systolic anterior motion
  • table motion
  • thermal motion
  • three-dimensional motion
  • torsional motion
  • translational motion
  • vertical motion
  • vibrational motion
  • visual motion
  • wall motion
  • water motion
  • wave motion

  • Terms modified by Motion

  • motion abnormality
  • motion analysis
  • motion analysis system
  • motion artifact
  • motion capture
  • motion capture data
  • motion capture system
  • motion characteristic
  • motion compensation
  • motion control
  • motion correction
  • motion detection
  • motion duration
  • motion effects
  • motion equation
  • motion information
  • motion parameter
  • motion pattern
  • motion perception
  • motion planning
  • motion prediction
  • motion process
  • motion score index
  • motion sensitivity
  • motion sickness
  • motion system

  • Selected Abstracts


    ECONOMIC AFFAIRS, Issue 2 2009
    Saad Azmat
    This paper uses Douglass North's theories of institutional economics to explain progress in Muslim Spain. It argues that it was efficient economic institutions in the guise of a free-market economy where the property rights of different strata of society were well protected, which ensured lasting prosperity. This paper postulates that while a population explosion could have been responsible for the initial growth in Spain, it was an efficient formal,informal institutional matrix that ensured a high level of long-term growth. [source]


    Jakub Novák
    ABSTRACT. This contribution attempts to reveal the relations between new suburban areas and other parts of the Prague metropolitan area by investigating the time-space activity and mobility patterns of the inhabitants of newly built suburban districts. The focus on some aspects of the everyday life of people in new suburbs helps us to identify the impact of suburbanization on the changing geography of the metropolitan region and to better understand how the spatial organization of the Prague metropolitan area is produced, reproduced and transformed. We use several interrelated concepts, which serve the theoretical foundation of our work, namely time geography, structuration theory and the post-communist city. The empirical data utilized are primarily based on 262 diaries completed by eighty-eight individuals from thirty-eight households, accompanied by household questionnaires and interviews with the heads of households. The research confirmed the implicit, generally unspoken view that new suburbs in the Prague metropolitan region are heavily dependent on the core of the metropolitan area for the provision of jobs and services. However, newly built suburban shopping facilities to some extent disrupt this pattern, keeping some daily activities of inhabitants within the suburban zone. In addition to empirical observations, the key purpose of this contribution has been to discuss and apply time geography concepts and methods to the research of urban restructuring, and to understand the structuration of metropolitan spatial organization. [source]


    JOURNAL OF PHYCOLOGY, Issue 3 2000
    Catriona L. Hurd
    Water motion is a key determinant of marine macroalgal production, influencing directly or indirectly physiological rates and community structure. Our understanding of how marine macroalgae interact with their hydrodynamic environment has increased substantially over the past 20 years, due to the application of tools such as flow visualization to aquatic vegetation, and in situ measurements of seawater velocity and turbulence. This review considers how the hydrodynamic environment in which macroalgae grow influences their ability to acquire essential resources and how macroalgae might respond physiologically to fluctuations in their hydrodynamic regime with a focus on: (1) the biochemical processes occurring within the diffusion boundary layer (DBL) that might reduce rates of macroalgal production; (2) time scales over which measurements of velocity and DBL processes should be made, discussing the likelihood of in situ mass transfer limitation; (3) if and how macroalgal morphology influences resource acquisition in slow flows; and (4) ecobiomechanics and how hydrodynamic drag might influence resource acquisition and allocation. Finally, the concept that macroalgal production is enhanced in wave-exposed versus sheltered habitats is discussed. [source]

    Pose Controlled Physically Based Motion

    Raanan Fattal
    Abstract In this paper we describe a new method for generating and controlling physically-based motion of complex articulated characters. Our goal is to create motion from scratch, where the animator provides a small amount of input and gets in return a highly detailed and physically plausible motion. Our method relieves the animator from the burden of enforcing physical plausibility, but at the same time provides full control over the internal DOFs of the articulated character via a familiar interface. Control over the global DOFs is also provided by supporting kinematic constraints. Unconstrained portions of the motion are generated in real time, since the character is driven by joint torques generated by simple feedback controllers. Although kinematic constraints are satisfied using an iterative search (shooting), this process is typically inexpensive, since it only adjusts a few DOFs at a few time instances. The low expense of the optimization, combined with the ability to generate unconstrained motions in real time yields an efficient and practical tool, which is particularly attractive for high inertia motions with a relatively small number of kinematic constraints. [source]

    Dynamic Textures for Image-based Rendering of Fine-Scale 3D Structure and Animation of Non-rigid Motion

    Dana Cobza
    The problem of capturing real world scenes and then accurately rendering them is particularly difficult for fine-scale 3D structure. Similarly, it is difficult to capture, model and animate non-rigid motion. We present a method where small image changes are captured as a time varying (dynamic) texture. In particular, a coarse geometry is obtained from a sample set of images using structure from motion. This geometry is then used to subdivide the scene and to extract approximately stabilized texture patches. The residual statistical variability in the texture patches is captured using a PCA basis of spatial filters. The filters coefficients are parameterized in camera pose and object motion. To render new poses and motions, new texture patches are synthesized by modulating the texture basis. The texture is then warped back onto the coarse geometry. We demonstrate how the texture modulation and projective homography-based warps can be achieved in real-time using hardware accelerated OpenGL. Experiments comparing dynamic texture modulation to standard texturing are presented for objects with complex geometry (a flower) and non-rigid motion (human arm motion capturing the non-rigidities in the joints, and creasing of the shirt). Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Image Based Rendering [source]

    Right Ventricular Function in Congenital Heart Defects Assessed by Regional Wall Motion

    FSCAI, Michael R. Nihill MB
    ABSTRACT Objectives., To develop a simple method to assess right ventricular function by angiography. Background., Conventional methods of evaluating right ventricular function are inaccurate, cumbersome, and expensive. Methods., We analyzed biplane right ventricular angiograms taken in the posterior,anterior and lateral projections using software to measure right ventricular volumes and regional wall motion in 78 patients with normal hearts (n = 29), atrial septal defects (ASD n = 13), pulmonary valve stenosis (PVS n = 21), and postoperative atrial switch patients (n = 15). We also measured the shortening fraction (SF) from the midtricuspid annulus to the septum and correlated various angiographic measurements with the right ventricular (RV) ejection fraction. Results., The volume-overloaded patients (ASD) had larger end diastolic volumes and increased SF compared with normal patients, while the pressure-loaded patients (PVS) had normal volumes and SF. The postoperative atrial switch patients had decreased systolic function and increased end diastolic volume. The SF for all of the patients correlated with the ejection fraction (r= 0.785, P, .0001). Conclusions., A simple measurement of the end diastolic and end systolic distance from the midtricuspid annulus to the septum (SF) provides a good index of RV function by angiography and correlates well with RV ejection fraction. [source]

    Estimating the mean speed of laminar overland flow using dye injection-uncertainty on rough surfaces

    David Dunkerley
    Abstract A common method for estimating mean flow speeds in studies of surface runoff is to time the travel of a dye cloud across a measured flow path. Motion of the dye front reflects the surface flow speed, and a correction must be employed to derive a value for the profile mean speed, which is always lower. Whilst laminar flow conditions are widespread in the interrill zone, few data are available with which to establish the relationship linking surface and profile mean speeds, and there are virtually none for the flow range 100,<,Re,<,500 (Re,=,Reynolds number) which is studied here. In laboratory experiments on a glued sand board, mean flow speeds were estimated from both dye speeds and the volumetric flow relation v,=,Q/wd with d measured using a computer-controlled needle gauge at 64 points. In order to simulate conditions applicable to many dryland soils, the board was also roughened with plant litter and with ceramic tiles (to simulate surface stone cover). Results demonstrate that in the range 100,<,Re,<,500, there is no consistent relation between surface flow speeds and the profile mean. The mean relationship is v,=,0·56 vsurf, which departs significantly from the theoretical smooth-surface relation v,=,0·67 vsurf, and exhibits a considerable scatter of values that show a dependence on flow depth. Given the inapplicability of any fixed conversion factor, and the dependence on flow depth, it is suggested that the use of dye timing as a method for estimating v be abandoned in favour of precision depth measurement and the use of the relation v,=,Q/wd, at least within the laminar flow range tested. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Evidence of Robust Coupling of Atrioventricular Mechanical Function of the Right Side of the Heart: Insights from M-Mode Analysis of Annular Motion

    ECHOCARDIOGRAPHY, Issue 6 2008
    Raveen Bazaz M.D.
    Background: Extensive data exist regarding annular descent and ventricular function. We have already demonstrated significant differences in amplitude and timing of events between maximal mitral (MAPSE) and tricuspid (TAPSE) annular plane systolic excursion as well as described quantitative temporal differences in annular ascent (AA) between the right and left sides of the heart. However, whether any relationship exists between annular ascent and descent components remains uninvestigated. Methods: Left ventricular ejection fraction (LVEF), right ventricular fractional area change (RVFAC), MAPSE, TAPSE, MV, and TV AA as well as pulsed tissue Doppler of the lateral MV and TV annuli were recorded from 53 patients. Results: In this population (age 55 ± 17 years) mean LVEF was 55 ± 19%, mean RVFAC was 47 ± 20%, mean MAPSE was 2.11 ± 0.72 cm, mean TAPSE was 1.48 ± 0.44 cm, mean MV AA was 0.52 ± 0.17 cm, TV AA was 0.96 ± 0.47, MV A-wave 0.10 ± 0.04 cm/s, and TV A-wave was 0.13 ± 0.05 cm/s. A more robust correlation was seen between TV AA and RVFAC than between MV AA and LVEF and also between TV AA and pulsed TDI TV A-wave velocity than between MV AA and pulsed TDI MV A-wave. Conclusion: Our data reveal that mechanical systolic functions of the atria and the ventricles are more closely coupled on the right than on the left side of the heart. Whether this is a result of anatomic linking or chamber geometry will require further study. [source]

    Amplitude and Velocity of Mitral Annulus Motion in Rabbits

    ECHOCARDIOGRAPHY, Issue 4 2004
    Li-ming Gan M.D., Ph.D.
    Objective: During recent years, the amplitude and the maximal systolic velocity of the mitral annulus motion (MAM) have been established as indices of the left ventricular systolic function and the maximal diastolic velocity of the annulus motion has been suggested as an index of diastolic function. The main aims of the present study were to investigate the feasibility of these techniques in rabbits and to investigate age-related changes concerning these variables. Methods: Twenty-one New Zealand white rabbits were investigated by echocardiographic M-mode and pulsed tissue Doppler. One subgroup (I) included 11 still-growing, 3.0 ± 0.2 month-old, animals and another group (II) included 10 young grown up rabbits, 12.1 ± 1.5 months old. Results: The amplitude (4.8 ± 0.6 and 3.5 ± 0.3 mm, respectively) and maximal systolic (98 ± 14 and 66 ± 7 mm/s, respectively) and diastolic (111 ± 21 and 80 ± 12 mm/s, respectively) velocities of the MAM were significantly (P < 0.001) higher in group I than in group II, despite a bigger heart in the animals in the latter group. A coefficient of variation of <5% was found for both inter- and intraobserver variability for both amplitude and velocities. Conclusions: The amplitude and velocities of MAM are easily recorded in rabbits with excellent reproducibility and the changes with age seem to be very similar to those in humans. These noninvasive M-mode and tissue Doppler methods are therefore suitable for the investigation of left ventricular function in experimental studies in rabbits. (ECHOCARDIOGRAPHY, Volume 21, May 2004) [source]

    Molecular Motion and Performance Enhancement of BORAZAN Fluorescent Dyes

    Tyler J. Morin
    Abstract The preparation of three 2,6-dipyrazolyl-4-X-anilines, H(pz2AnX) (X = p -CF3, Cl, tBu) using CuI-catalyzed amination is described. Subsequent reactions of H(pz2AnX) with triphenylboron proceeds with benzene elimination to give the corresponding Ph2B(pz2AnX) compounds in high yields. The Ph2B(pz2AnX) are more highly emissive in the solid state than the previously reported BORAZAN fluorophores, Ph2B(pzAnX), their monopyrazolyl counterparts. As with the Ph2B(pzAnX), the color of emission in Ph2B(pz2AnX) can be tuned simply by varying the para -aniline substituent where the emission of Ph2B(pz2AnX) is red-shifted relative to the corresponding Ph2B(pzAnX) derivatives. The electronic properties were studied by cyclic voltammetry and electronic absorption/emission spectroscopy as well as by density functional calculations (B3LYP/6-31G*). The di-pyrazolyl derivatives exhibit greater stability toward solvolysis and higher photoluminescent quantum yields (despite the red-shift in emission) compared to their monopyrazolyl counterparts presumably due to kinetic stabilization of the chromophore imparted by the second pyrazolyl ligand. For Ph2B(pz2AnX), evidence for intramolecular motion of the diphenylboryl moiety traversing both pyrazolyl groups was detected by variable temperature 1H NMR spectroscopy. The rate increases with increasing electron-donor abilities of the para -aniline substituent.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Torsional Motion in (tert -Butyl)ammonium Hemispheraplexes: Rotational Barriers and Energy of Binding

    The ADPs (ADPs=atomic anisotropic displacement parameters) from the single-crystal X-ray studies of nine related TBA+ (TBA+=(tert -butyl)ammonium) hemispheraplexes are analyzed, and the results compared to the free energy of binding of this guest by the nine hosts. The lipophilic hosts (Fig.,1) were synthesized over a number of years, with increasing pre-organization for and specificity of binding. Structural studies for six of the complexes have been published, but the remaining three structures, including those of the strongest binders of TBA+, are disordered and have only now been completed. New area-detector data has been analyzed for the TBA+ClO complexes of 5 and of 8 at two temperatures, while the original data for 9,TBA+SCN, has been treated with a disorder model. In addition, improved models are presented for the complexes of 6 and 7. Methods for assessing the precision of the ADP analyses are discussed. Although most of the structures are imprecise, the TBA+ groups do demonstrate some of the characteristics of independent motion. The general trend in calculated libration amplitudes for the TBA+ group suggests that the guests with the greatest free energy of binding, and the shortest distances from N+ to the ligand plane, are those with the highest barriers to internal rotation. [source]

    Type of Maternal Object Motion During Synchronous Naming Predicts Preverbal Infants' Learning of Word,Object Relations

    INFANCY, Issue 2 2008
    Dalit J. Matatyaho
    Mothers' use of specific types of object motion in synchrony with object naming was examined, along with infants' joint attention to the mother and object, as a predictor of word learning. During a semistructured 3-min play episode, mothers (N = 24) taught the names of 2 toy objects to their preverbal 6- to 8-month-old infants. The episodes were recoded from Gogate, Bolzani, and Betancourt (2006) to provide a more fine-grained description of object motions used by mothers during naming. The results indicated that mothers used forward/downward and shaking motions more frequently and upward and backward motions less frequently in temporal synchrony with the spoken words. These motions likely highlight novel word,object relations. Furthermore, maternal use of shaking motions in synchrony with the spoken words and infants' ability to switch gaze from mother to object contributed to infants' learning of the word,object relations, as observed on a posttest. Thus, preverbal infants' learn word,object relations within an embodied system involving tightly coupled interaction between infants' perception and joint attention, and specific properties of caregivers' naming. [source]

    Infants' Evolving Representations of Object Motion During Occlusion: A Longitudinal Study of 6- to 12-Month-Old Infants

    INFANCY, Issue 2 2004
    Gustaf Gredebäck
    Infants' ability to track temporarily occluded objects that moved on circular trajectories was investigated in 20 infants using a longitudinal design. They were first seen at 6 months and then every 2nd month until the end of their 1st year. Infants were presented with occlusion events covering 20% of the target's trajectory (effective occlusion interval ranged from 500,4,000 msec). Gaze was measured using an ASL 504 infrared eye-tracking system. Results effectively demonstrate that infants from 6 months of age can represent the spatiotemporal dynamics of occluded objects. Infants at all ages tested were able to predict, under certain conditions, when and where the object would reappear after occlusion. They moved gaze accurately to the position where the object was going to reappear and scaled their timing to the current occlusion duration. The average rate of predictive gaze crossings increased with occlusion duration. These results are discussed as a 2-factor process. Successful predictions are dependent on strong representations, themselves dependent on the richness of information available during encoding and graded representations. [source]

    Four-Month-Olds' Discrimination of Optic Flow Patterns Depicting Different Directions of Observer Motion

    INFANCY, Issue 2 2003
    Rick O. Gilmore
    One of the most powerful sources of information about spatial relationships available to mobile organisms is the pattern of visual motion called optic flow. Despite its importance for spatial perception and for guiding locomotion, very little is known about how the ability to perceive one's direction of motion, or heading, from optic flow develops early in life. In this article, we report the results of 3 experiments that tested the abilities of 4-month-old infants to discriminate optic flow patterns simulating different directions of self-motion. The combined results from 2 different experimental paradigms suggest that 4-month-olds discriminate optic flow patterns that simulate only large (> 32°) changes in the direction of the observer's motion through space. This suggests that prior to the onset of locomotion, there are limitations on infants' abilities to process patterns of optic flow related to self-motion. [source]

    Nanotopographic Carbon Nanotube Thin-Film Substrate Freezes Lateral Motion of Secretory Vesicles

    ADVANCED MATERIALS, Issue 7 2009
    Jing Zhang
    Thin-film carbon-nanotube networks can interface with living neuroendocrine PC12 cells and support their growth and proliferation. Interestingly, as revealed by total-internal-reflection fluorescence microscopy, the nanoroughness created by the carbon-nanotube net physically deforms the 5,nm thick cell membrane with high local curvature, and significantly impedes the lateral motion of subplasmalemmal secretory vesicles. [source]

    A volume-of-fluid method for incompressible free surface flows

    I. R. Park
    Abstract This paper proposes a hybrid volume-of-fluid (VOF) level-set method for simulating incompressible two-phase flows. Motion of the free surface is represented by a VOF algorithm that uses high resolution differencing schemes to algebraically preserve both the sharpness of interface and the boundedness of volume fraction. The VOF method is specifically based on a simple order high resolution scheme lower than that of a comparable method, but still leading to a nearly equivalent order of accuracy. Retaining the mass conservation property, the hybrid algorithm couples the proposed VOF method with a level-set distancing algorithm in an implicit manner when the normal and the curvature of the interface need to be accurate for consideration of surface tension. For practical purposes, it is developed to be efficiently and easily extensible to three-dimensional applications with a minor implementation complexity. The accuracy and convergence properties of the method are verified through a wide range of tests: advection of rigid interfaces of different shapes, a three-dimensional air bubble's rising in viscous liquids, a two-dimensional dam-break, and a three-dimensional dam-break over an obstacle mounted on the bottom of a tank. The standard advection tests show that the volume advection algorithm is comparable in accuracy with geometric interface reconstruction algorithms of higher accuracy than other interface capturing-based methods found in the literature. The numerical results for the remainder of tests show a good agreement with other numerical solutions or available experimental data. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Cover Picture: Programmable Motion and Separation of Single Magnetic Particles on Patterned Magnetic Surfaces (Adv. Mater.

    ADVANCED MATERIALS, Issue 14 2005
    Abstract Structured magnetic surfaces enabling programmable motion of single micrometer-sized magnetic particles are reported on p.,1730 by Gunnarsson and co-workers. Patterns of thin-film magnetic elements are tailored to form transport lines with junctions for the separation of individual particles. This method has the potential to improve and generate new applications in biotechnology. The cover shows a schematic of the transportation and separation of magnetic particles functionalized with antibodies capable of selectively capturing the corresponding analytes from a sample. [source]

    Browsing, Bouncing, Murdering, and Mooring

    Negotiating the Relationship Between Inhabitation, Representation
    This paper presents the theoretical context and results of an advanced research seminar, Visualizing Information in Space, Time, and Motion, that explores the production of space with respect to the spatial inhabitation of our built environment, strategies of representation, and the research, analysis, synthesis, and construction of notation communicating perceived aspects of space, time, and motion. [source]

    The four horsemen of tech: Has another bubble burst?

    Damir Tokic
    After the subprime mortgage bubble burst, people started looking around to see if other disasters were on the horizon. In the high-tech sector, the stocks of four companies,Google, Apple, Research in Motion, and,provided strong market leadership during 2007. But following their steep rise in the second half of 2007, the stocks of these "new four horseman of tech" suffered a sharp correction. Has another bubble burst? If so, what does it mean for the broader market? © 2008 Wiley Periodicals, Inc. [source]

    Multiple-bolus dynamic contrast-enhanced MRI in the pancreas during a glucose challenge

    J.H. Naish PhD
    Abstract Purpose: To assess the feasibility of multiple-bolus dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in the pancreas; to optimize the analysis; and to investigate application of the method to a glucose challenge in type 2 diabetes. Materials and Methods: A 4-bolus DCE-MRI protocol was performed on five patients with type 2 diabetes and 11 healthy volunteers during free-breathing. Motion during the dynamic time series was corrected for using a model-driven nonlinear registration. A glucose challenge was administered intravenously between the first and second DCE-MRI acquisition in all patients and in seven of the healthy controls. Results: Image registration improved the reproducibility of the DCE-MRI model parameters across the repeated bolus-acquisitions in the healthy controls with no glucose challenge (eg, coefficient of variation for Ktrans improved from 38% to 28%). Native tissue T1 was significantly lower in patients (374 ± 68 msec) compared with volunteers (519 ± 41 msec) but there was no significant difference in any of the baseline DCE-MRI parameters. No effect of glucose challenge was observed in either the patients or healthy volunteers. Conclusion: Multiple bolus DCE-MRI is feasible in the pancreas and is improved by nonlinear image registration but is not sensitive to the effects of an intravenous glucose challenge. J. Magn. Reson. Imaging 2010;32:622,628. © 2010 Wiley-Liss, Inc. [source]

    7 Tesla MR imaging of the human eye in vivo

    Kathryn Richdale OD
    Abstract Purpose: To develop a protocol which optimizes contrast, resolution and scan time for three-dimensional (3D) imaging of the human eye in vivo using a 7 Tesla (T) scanner and custom radio frequency (RF) coil. Materials and Methods: Initial testing was conducted to reduce motion and susceptibility artifacts. Three-dimensional FFE and IR-TFE images were obtained with variable flip angles and TI times. T1 measurements were made and numerical simulations were performed to determine the ideal contrast of certain ocular structures. Studies were performed to optimize resolution and signal-to-noise ratio (SNR) with scan times from 20 s to 5 min. Results: Motion and susceptibility artifacts were reduced through careful subject preparation. T1 values of the ocular structures are in line with previous work at 1.5T. A voxel size of 0.15 × 0.25 × 1.0 mm3 was obtained with a scan time of approximately 35 s for both 3D FFE and IR-TFE sequences. Multiple images were registered in 3D to produce final SNRs over 40. Conclusion: Optimization of pulse sequences and avoidance of susceptibility and motion artifacts led to high quality images with spatial resolution and SNR exceeding prior work. Ocular imaging at 7T with a dedicated coil improves the ability to make measurements of the fine structures of the eye. J. Magn. Reson. Imaging 2009;30:924,932. © 2009 Wiley-Liss, Inc. [source]

    Improved dynamic susceptibility contrast (DSC)-MR perfusion estimates by motion correction

    Robert K. Kosior BSc
    Abstract Purpose To investigate the effect of patient motion on quantitative cerebral blood flow (CBF) maps in ischemic stroke patients and to evaluate the efficacy of a motion-correction scheme. Materials and Methods Perfusion data from 25 ischemic stroke patients were selected for analysis. Two motion profiles were applied to a digital anthropomorphic brain phantom to estimate accuracy. CBF images were generated for motion-corrupted and motion-corrected data. To correct for motion, rigid-body registration was performed. The realignment parameters and mean CBF in regions of interest were recorded. Results All patient data with motion exhibited visibly reduced intervolume misalignment after motion correction. Improved flow delineation between different tissues and a more clearly defined ischemic lesion (IL) were achieved in the motion-corrected CBF. A significant difference occurred in the IL (P < 0.05) for patients with severe motion with an average difference between corrupted and corrected data of 4.8 mL/minute/100 g. The phantom data supported the patient results with better CBF accuracy after motion correction and high registration accuracy (<1 mm translational and <1° rotational error). Conclusion Motion degrades flow differentiation between adjacent tissues in CBF maps and can cause ischemic severity to be underestimated. A registration motion correction scheme improves dynamic susceptibility contrast (DSC)-MR perfusion estimates. J. Magn. Reson. Imaging 2007;26:1167,1172. © 2007 Wiley-Liss, Inc. [source]

    Anti-inflammatory effects of continuous passive motion on meniscal fibrocartilage

    Mario Ferretti
    Abstract Motion-based therapies have been applied to promote healing of arthritic joints. The goal of the current study was to determine the early molecular events that are responsible for the beneficial actions of motion-based therapies on meniscal fibrocartilage. Rabbit knees with Antigen-Induced-Arthritis (AIA) were exposed to continuous passive motion (CPM) for 24 or 48 h and compared to immobilized knees. The menisci were harvested and glycosaminoglycans (GAG), interleukin-1, (IL-1,), matrix metalloproteinase-1 (MMP-1), cyclooxygenase-2 (COX-2), and interleukin-10 (IL-10) were determined by histochemical analysis. Within 24 h, immobilized knees exhibited marked GAG degradation. The expression of proinflammatory mediators MMP-1, COX-2, and IL-1, was notably increased within 24 h and continued to increase during the next 24 h in immobilized knees. Knees subjected to CPM revealed a rapid and sustained decrease in GAG degradation and the expression of all proinflammatory mediators during the entire period of CPM treatment. More importantly, CPM induced synthesis of the anti-inflammatory cytokine IL-10. The results demonstrate that mechanical signals generated by CPM exert potent anti-inflammatory signals on meniscal fibrochondrocytes. Furthermore, these studies explain the molecular basis of the beneficial effects of CPM observed on articular cartilage and suggest that CPM suppresses the inflammatory process of arthritis more efficiently than immobilization. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]

    Superplasticity of a Fine-Grained TZ3Y Material Involving Dynamic Grain Growth and Dislocation Motion

    Guillaume Bernard-Granger
    Superplastic deformation of a fully dense TZ3Y material, having a starting grain size around 135,145 nm and depleted of any amorphous phase at grain boundaries, has been investigated using compressive creep tests in air in the temperature range of 1100°,1300°C and the real stress range of 50,100 MPa. The key parameters of the creep law have been determined by performing temperature changes at a fixed stress and stress jumps at a fixed temperature. From such experiments, an average value for the apparent stress exponent of around 3 is obtained when the applied stress varied from 50 to 100 MPa and the temperature was kept constant in the range of 1100°,1300°C. The apparent activation energy of the mechanism controlling the creep deformation is evaluated at 577±75 kJ/mol in the temperature range of 1200°,1300°C, for a real stress of 70 MPa. The values of the apparent grain size exponent can be calculated from the initial grain size in the as-sintered samples and the grain size in the crept samples. In all cases, it was determined to be around 2. Observation of the microstructure of the crept samples, using scanning electron microscopy, reveals grain growth but does not show any significant elongation of the elemental grains. Transmission electron microscopy of a sample crept under 100 MPa at 1300°C reveals clear intragranular dislocation activity. This dislocation activity seems to be mainly confined in folds emitted at triple points. Because the creep parameters (experimental and calculated using a simple geometric model) and the microstructure observed are in good agreement, we propose that the creep mechanism involved is grain boundary sliding accommodated by dynamic grain growth and the formation of triple-point folds. [source]

    Impact of the Sampling Rate on the Estimation of the Parameters of Fractional Brownian Motion

    Zhengyuan Zhu
    Primary 60G18; secondary 62D05, 62F12 Abstract., Fractional Brownian motion is a mean-zero self-similar Gaussian process with stationary increments. Its covariance depends on two parameters, the self-similar parameter H and the variance C. Suppose that one wants to estimate optimally these parameters by using n equally spaced observations. How should these observations be distributed? We show that the spacing of the observations does not affect the estimation of H (this is due to the self-similarity of the process), but the spacing does affect the estimation of the variance C. For example, if the observations are equally spaced on [0, n] (unit-spacing), the rate of convergence of the maximum likelihood estimator (MLE) of the variance C is . However, if the observations are equally spaced on [0, 1] (1/n -spacing), or on [0, n2] (n -spacing), the rate is slower, . We also determine the optimal choice of the spacing , when it is constant, independent of the sample size n. While the rate of convergence of the MLE of C is in this case, irrespective of the value of ,, the value of the optimal spacing depends on H. It is 1 (unit-spacing) if H = 1/2 but is very large if H is close to 1. [source]

    Simulating a class of stationary Gaussian processes using the Davies,Harte algorithm, with application to long memory processes

    We demonstrate that the fast and exact Davies,Harte algorithm is valid for simulating a certain class of stationary Gaussian processes , those with a negative autocovariance sequence for all non-zero lags. The result applies to well known classes of long memory processes: Gaussian fractionally differenced (FD) processes, fractional Gaussian noise (fGn) and the nonstationary fractional Brownian Motion (fBm). [source]

    Labour Market in Motion: Analysing Regional Flows in a Multi-accounting System

    LABOUR, Issue 4-5 2007
    Anette Haas
    We develop a flexible flow approach system , a multi-accounting system (MAS) , dealing with flows and stocks on regional labour markets. Combining administrative data at the micro level with various macro data, the MAS describes the dynamic transition process of the 180 local labour market areas in Germany. We use a new algorithm, related to entropy optimization, to estimate unknown transitions. Compared with conventional methods, the main advantage of our proceeding is that additional information from different data sources can be included that is of an inherently fuzzy character. [source]

    Anisotropic Motion of Electroactive Papers Coated with PEDOT/PSS

    Jian Zhou
    Abstract We report on an anisotropic actuation of electroactive papers with a PEDOT/PSS coating in ambient air. PEDOT/PSS-coated papers were prepared by wetting Manila papers with a concentrated PEDOT/PSS aqueous dispersion and subsequent drying. The electroactive papers displayed a contractile stress when an external voltage was applied, the magnitude and direction of the stress depending on the relative orientation of paper fibers and the loading direction of the coating. We also demonstrated that a butterfly-like reversible bending motion of the PEDOT/PSS coated paper occurred when the voltage switching between on and off. [source]

    Motion According to Aquinas and Newton

    MODERN THEOLOGY, Issue 2 2001
    Simon Oliver
    This article seeks to examine the theological basis of the understanding of motion in the work of Aquinas and Newton. As well as the Aristotelian roots of Aquina's view, attention is also paid to motion understood as a participation in the perfect ,motionless motion' of the emanation of the Son from the Father. This is contrasted with the crucial theological context of Newton's view of motion as expressed in the Principia, namely his Arianism and theological voluntarism. Motion becomes a purely physical and spatial category predicted on violent competition rather than mutual enhancement and the goal of perfection. Meanwhile, it is suggested that Newton has to resort to unmediated divine action within absolute and eternal space in order to describe how a universe in motion might have anything to do with God. [source]

    A Method for Measuring the Motion of Culture

    Greg Urban
    ABSTRACT, Beginning with Edward Tylor's (1889) definition of culture as socially "acquired," I focus in this article on motion as social acquisition and transmission through "artifacts",both durable (like ceramic pots) and fleeting (like sounds). Motion can be detected by comparison of the artifacts to which people are exposed with those they in turn produce. I examine rates of interaction with artifacts and changes in rates as evidence of the operation of "forces" such as interest and metaculture. I develop a set of axioms or laws of motion, growing out of fine-grained research on naturally occurring discourse, and endeavor to demonstrate their utility through application to three empirical cases. Although I deal with relatively small-scale artifacts, I conclude this article with the suggestion that its methods may prove useful in the broader study of cultural phenomena. [source]