Different Kinds Of Motion Research Articles

Motion estimation of 3D coronary vessel skeletons from X-ray angiographic sequences

A method for quantitatively estimating global displacement fields of coronary arterial vessel skeletons during cardiac cycles from X-ray coronary angiographic (CAG) image sequences is proposed. First, dynamic sequence of arterial lumen skeletons is semi-automatically reconstructed from a pair of angiographic image sequences acquired from two nearly orthogonal view angles covering one or several cardiac cycles. Then, displacement fields of 3D vessel skeletons at different cardiac phases are quantitatively estimated through searching optimal correspondences between skeletons of a same vessel branch at different time-points of image sequences with dynamic programming algorithm. The main advantage of this method is that possible errors introduced by calibration parameters of the imaging system are avoided and application of dynamic programming ensures low computation cost. Also, any a priori knowledge and model about cardiac and arterial dynamics is not needed and the same matching error function and similarity measurement can be used to estimate global displacement fields of vessel skeletons performing different kinds of motion. Validation experiments with computer-simulated data and clinically acquired image data are designed and results are given to demonstrate the accuracy and validity of the proposed method.

Analysis of mixed motion in deterministic ratchets via experiment and particle simulation

Deterministic lateral displacement (DLD) ratchets are microfluidic devices, which are used for size-based sorting of cells or DNA. Based on their size, particles are showing different kinds of motion, leading to their fractionation. In earlier studies, so-called zigzag and displacement motions are observed, and in recent study by our group (Kulrattanarak et al., Meas Sci Technol, 2010a; J Colloid Interface Sci, 2010b), we have shown that also mixed motion occurs, which is an irregular alternation of zigzag and displacement motion. We have shown that the mixed motion is due to asymmetry of the flow lane distribution, induced by the symmetry breaking of the oblique primitive lattice cell (Kulrattanarak et al. 2010b). In this study, we investigate mixed motion in depth by numerical and experimental analysis. Via 3D simulations, we have computed explicit particle trajectories in DLD, and are able to show that there are two critical length scales determining the type of motion. The first length scale df,1 is the first flow lane width, which determines the transition between zigzag motion and mixed motion. The other length scale, df,c, determines the transition between mixed motion and displacement motion. Based on our experimental and numerical results we have been able to correlate the migration angle of particles showing mixed motion to the particle size, relative to the two critical length scales df,1 and df,c.

An All-Electric Single-Molecule Motor

Many types of molecular motors have been proposed and synthesized in recent years, displaying different kinds of motion, and fueled by different driving forces such as light, heat, or chemical reactions. We propose a new type of molecular motor based on electric field actuation and electric current detection of the rotational motion of a molecular dipole embedded in a three-terminal single-molecule device. The key aspect of this all-electronic design is the conjugated backbone of the molecule, which simultaneously provides the potential landscape of the rotor orientation and a real-time measure of that orientation through the modulation of the conductivity. Using quantum chemistry calculations, we show that this approach provides full control over the speed and continuity of motion, thereby combining electrical and mechanical control at the molecular level over a wide range of temperatures. Moreover, chemistry can be used to change all key parameters of the device, enabling a variety of new experiments on molecular motors.

Multicamera tracking of articulated human motion using shape and motion cues

We present a completely automatic algorithm for initializing and tracking the articulated motion of humans using image sequences obtained from multiple cameras. A detailed articulated human body model composed of sixteen rigid segments that allows both translation and rotation at joints is used. Voxel data of the subject obtained from the images is segmented into the different articulated chains using Laplacian Eigenmaps. The segmented chains are registered in a subset of the frames using a single-frame registration technique and subsequently used to initialize the pose in the sequence. A temporal registration method is proposed to identify the partially segmented or unregistered articulated chains in the remaining frames in the sequence. The proposed tracker uses motion cues such as pixel displacement as well as 2-D and 3-D shape cues such as silhouettes, motion residue, and skeleton curves. The tracking algorithm consists of a predictor that uses motion cues and a corrector that uses shape cues. The use of complementary cues in the tracking alleviates the twin problems of drift and convergence to local minima. The use of multiple cameras also allows us to deal with the problems due to self-occlusion and kinematic singularity. We present tracking results on sequences with different kinds of motion to illustrate the effectiveness of our approach. The pose of the subject is correctly tracked for the duration of the sequence as can be verified by inspection.

Photophoresis—Light induced motion of particles suspended in gas

When irradiated sideways, by visible light, a particle can perform different kinds of motion, (e.g. in direction of irradiation, opposite to irradiation, vertical movement, helicoidally, etc.). This phenomenon is called photophoresis. Photophoresis is based on momentum transfer between the aerosol particle and surrounding gas molecules. Photophoresis strongly depends on the pressure of the surrounding gas. Particles mostly influenced by photophoresis are those of μm size. Two main types of forces describe photophoretic motion: Δ T force: The thermal accommodation coefficient α is constant over the particle surface. As a result of the thermal accommodation, gas molecules on the warm side of a particle leave the surface faster than gas molecules on the cold side. This leads to Δ T force on the particle towards the colder side. Typical motion of the particle will be either away from light irradiation ( positive photophoresis), or in direction of light irradiation ( negative photophoresis). In the case of negative photophoresis, the back side of the particle, due the nature of light absorption, will be heated more than front side of the particle. Δ α force: If the particle is at a constant temperature, which is different from the temperature of the surrounding gas, and the thermal accommodation coefficient α varies over the particle surface, the net momentum between gas molecules and particle will be transferred. In this case, the result will be body fixed Δ α force. Depending on the particle surface properties, Δ α force can direct the particle in any possible photophoresis could also play important role in planet formation and astrophysics.

A hero for their times: early biographies of NewtonIliffeRobKeynesMiloHiggittRebekaheds. Early biographies of Isaac Newton, 1660–1885(2 vols). Pickering & Chatto, London2006. pp. lxix +387; xlvii +420. £195.00 (hardback).1-85196-778-8.

Rob Iliffe, Milo Keynes, Rebekah Higgitt. eds. Early biographies of Isaac Newton, 1660–1885 (2 vols). Pickering & Chatto, London 2006. pp. lxix +387; xlvii +420. £195.00 (hardback). 1-85196-778-8. Though biography be no longer an act of worship, it is not yet a solemn and impartial judgment: we

Temporal pattern of source activities evoked by different types of motion onset stimuli

The aim of this study was to compare the time course of motion-related source activities evoked by the onset of different kinds of visual motion stimuli in human subjects. Event-related potentials (ERP) were recorded from 64 scalp electrodes in ten healthy subjects while they were viewing four different types of motion stimuli (translation, rotation, expansion and contraction). Following a new approach combining a current density reconstruction with clustering algorithms, source maxima in the time range from 50 to 400 ms after the onset of the visual stimulus were localized and the time courses of activation were elaborated. Six regions contributed significantly to source activity, half originating in the occipital lobe and half in the right parietal and right temporal cortex. The comparison of their time courses led to the following conclusions: (i) the different kinds of motion stimuli activated about the same areas of the brain but with different temporal patterns. (ii) Mainly parietal and extrastriate areas, but not V1/V2, were significantly involved in the differentiation of different kinds of motion. (iii) Contrasting the different kinds of motion onsets, responses from parietal areas were found mainly before those from lateral occipital areas. (iv) The classically defined N2 and P2 components were significantly different among the four motion conditions, but not P1. The N2 motion-related component was elicited not only by lateral occipital areas and middle temporal areas but also by right parietal areas. (v) The rotation condition evoked a novel component P180, concomitant with an increased activity in the left middle temporal gyrus.

Slow relaxations in salicylsalicylic acid studied by dielectric techniques

The dielectric techniques of Thermally Stimulated Depolarization Currents (TSDC) and Dielectric Relaxation Spectroscopy (DRS) were used in order to study the low frequency molecular motions in salicylsalicylic acid. Since this substance is a very effective glass-former, the molecular mobility was analyzed in the glassy state, in the metastable supercooled liquid state, and in the crystal. Four different kinds of motion have been detected and characterized: one in the crystal, two in the glass (α and β-relaxations) and one in the metastable liquid. Salicylsalicylic acid appears as a very strong glass former (fragility index m=31 on the Angell scale). In addition, the thermally stimulated depolarization current technique used in the study proved to be a very powerful tool to study slow molecular motion in this particular system.

Effect of “inverse melting transition” of aqueous triblock copolymer solutions on solute rotational dynamics

Rotational dynamics of two structurally similar hydrophobic solutes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP), has been investigated in 30% wv aqueous solution of triblock copolymer, poly(ethylene oxide)(20)-poly(propylene oxide)(70)-poly(ethylene oxide)(20) as a function of temperature. This study has been undertaken in an attempt to explore how the dynamics of a solute molecule solubilized in a copolymer solution is influenced when it undergoes sol-to-gel transition. It has been observed that the anisotropy decays of both DMDPP and DPP can be described by biexponential functions in the sol as well as in the gel phase. This observation has been rationalized on the basis of the probe molecule undergoing two different kinds of motion rather than being located in two different regions of the micelle. Even in the gel phase, which results as a consequence of micelle-micelle entanglement due to an increase in their volume fraction, the rotational relaxation of the solutes is similar to that observed in the micellar solution. The outcome of this work indicates that even though these gels have very high macroscopic viscosities and hence do not flow, the microenvironments experienced by the solutes are akin to that of a micellar solution.

2H-NMR Study and Molecular Dynamics Simulation of the Location, Alignment, and Mobility of Pyrene in POPC Bilayers

The alignment of pyrene in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer was investigated using two different approaches, namely solid-state 2H-NMR spectroscopy and molecular dynamics (MD) simulations. Quadrupolar splittings from 2H-NMR spectra of deuterated pyrene-d10 in an oriented lipid bilayer give information about the orientation of C-D bonds with respect to the membrane normal. From MD simulations, geometric information is accessible via trajectories. By defining molecular and bond order parameters, the data from MD trajectories and NMR spectra can be compared straightforwardly. To ensure that the results from both methods are comparable, parameters of the experimental and the simulation setup were chosen to be as similar as possible. From simulations, we saw that pyrene prefers a position inside the lipid membrane near the headgroups and has no tendency to diffuse from one monolayer of the membrane to the other. The results from simulation and NMR show that the normal of the molecular plane is aligned nearly perpendicular to the bilayer normal. The long axis of pyrene lies preferentially parallel to the bilayer normal within a range of ±30°. The results from the two different methods are remarkably consistent. The good agreement can be explained by the fact that the different kind of motions of a pyrene molecule are already averaged within a few nanoseconds, which is the timescale covered by the MD simulation.

A hybrid Fermi–Ulam-bouncer model

Some dynamical and chaotic properties are studied for a classical particle bouncing between two rigid walls, one of which is fixed and the other moves in time, in the presence of an external field. The system is a hybrid, behaving not as a purely Fermi–Ulam model, nor as a bouncer, but as a combination of the two. We consider two different kinds of motion of the moving wall: (i) periodic and (ii) random. The dynamics of the model is studied via a two-dimensional nonlinear area-preserving map. We confirm that, for periodic oscillations, our model recovers the well-known results of the Fermi–Ulam model in the limit of zero external field. For intense external fields, we establish the range of control parameters values within which invariant spanning curves are observed below the chaotic sea in the low energy domain. We characterize this chaotic low energy region in terms of Lyapunov exponents. We also show that the velocity of the particle, and hence also its kinetic energy, grow according to a power law when the wall moves randomly, yielding clear evidence of Fermi acceleration.

Does the Onset of Water Droplet Formation Alter the Microenvironment of the Hydrophobic Probes Solubilized in Nonionic Reverse Micelles?

The interiors of the reverse micelles formed with the surfactant Triton X-100 (TX-100) in benzene−n-hexane mixed solvent with an increasing water content, W = [H2O]/[TX-100], have been explored by monitoring the fluorescence anisotropies of two structurally similar but chemically distinct hydrophobic probes. The objective of this work is to find out how the formation of the water pool influences the location and mobility of these probe molecules. It has been observed that the anisotropies of both the probes 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) decay as a sum of two exponentials with slow and fast time constants. This experimental finding has been rationalized on the basis of a two-step model according to which the probe molecule undergoes two different kinds of motion inside the micelle. The average reorientation times of DPP are a factor of 4 longer than that of DMDPP. This observation in conjunction with the fact that the ...

Functional organization of parietal neuronal responses to optic-flow stimuli.

We analyzed the dissimilarity matrix of neuronal responses to moving visual stimuli using tree clustering and multidimensional scaling (MDS). Single-cell activity was recorded in area 7a while random dots moving coherently in eight different kinds of motion (right-, left-, up-, and downward, clockwise, counterclockwise, expansion, contraction) were presented to behaving monkeys with eyes fixated. Tree clustering analyses showed that the [rightward, leftward], [upward, downward], and [clockwise, counterclockwise]] motions were clustered in three separate branches (i.e., horizontal, vertical, and rotatory motion, respectively). In contrast, expansion was in a lone branch, whereas contraction was also separate but within a larger cluster. The distances among these clusters were then subjected to an MDS analysis to identify the dimensions underlying the tree clustering observed. This analysis revealed two major factors in operation. The first factor separated expansion from all other stimulus motions, which seems to reflect the prominence of expansion during the common activity of locomotion. In contrast, the second factor separated planar motions from motion in depth, which suggests that the latter may hold a special place in visual motion processing.

Neural substrates of action event knowledge.

Human concepts can be roughly divided into entities (prototypically referred to in language by nouns) and events (prototypically referred to in language by verbs). While much work in cognitive neuroscience has investigated how the brain represents different categories of entities, less attention has been given to the more basic distinction between entities and events. We used functional magnetic resonance imaging to examine brain activity while subjects performed a conceptual matching task that required them to access knowledge of objects and actions, using either pictures or words. Since action events involve movement through space, we hypothesized that accessing knowledge of actions would cause greater activation in brain regions involved in motion or spatial processing. In comparison to objects, accessing knowledge of actions through pictures was accompanied by increased activity bilaterally in the human MT/MST and nearby regions of the lateral temporal cortex. Accessing knowledge of actions through words activated areas just anterior and dorsal to area MT/MST on the left, within the posterior aspect of the middle and superior temporal gyri. We propose that the lateral occipital-temporal cortex contains a mosaic of neural regions that processes different kinds of motion, ranging from the perception of objects moving in the world to the conception of movement implied in action verbs. The lateral occipital-temporal cortex mediates the perceptual and conceptual features of action events, similar to the way that the ventral occipital-temporal cortex processes the perceptual and conceptual features of entities.

Effects of optic flow in motor cortex and area 7a.

Moving visual stimuli were presented to behaving monkeys who fixated their eyes and did not move their arm. The stimuli consisted of random dots moving coherently in eight different kinds of motion (right, left, up, downward, expansion, contraction, clockwise, and counterclockwise) and were presented in 25 square patches on a liquid crystal display projection screen. Neuronal activity in the arm area of the motor cortex and area 7a was significantly influenced by the visual stimulation, as assessed using an ANOVA. The percentage of cells with a statistically significant effect of visual stimulation was 3 times greater in area 7a (370/587, 63%) than in motor cortex (148/693, 21.4%). With respect to stimulus properties, its location and kind of motion had differential effects on cell activity in the two areas. Specifically, the percentage of cells with a significant stimulus location effect was approximately 2.5 times higher in area 7a (311/370, 84%) than in motor cortex (48/148, 32.4%), whereas the percentage of cells with a significant stimulus motion effect was approximately 2 times higher in the motor cortex (79/148, 53.4%) than in area 7a (102/370, 27.6%). We also assessed the selectivity of responses to particular stimulus motions using a Poisson train analysis and determined the percentage of cells that showed activation in only one stimulus condition. This percentage was 2 times higher in the motor cortex (73.7%) than in area 7a (37.7%). Of all kinds of stimulus motion tested, responses to expanding optic flow were the strongest in both cortical areas. Finally, we compared the activation of motor cortical cells during visual stimulation to that observed during force exertion in a center --> out task. Of 514 cells analyzed for both the motor and visual tasks, 388 (75.5%) showed a significant relation to either or both tasks, as follows: 284/388 (73.2%) cells showed a significant relation only to the motor task, 27/388 (7%) cells showed a significant relation only to the visual task, whereas the remaining 77/388 (19.8%) cells showed significant relations to both tasks. Therefore a total of 361/514 (70.2%) cells were related to the motor task and 104/514 (20.2%) were related to the visual task. Finally, with respect to receptive fields (RFs), there was no clear visual receptive field structure in the motor cortical neuronal responses, in contrast to area 7a where RFs were present and could be modulated by the type of optic flow stimulus.

Interchange, quasi‐interchange, ballooning modes: What is their exact definition?

Some confusion appears to remain among those in the magnetospheric community regarding the concepts of interchange, quasi‐interchange, and ballooning. By placing these different kinds of motions in the broader framework of a unified, comprehensive formalism on ideal magnetohydrodynamic (MHD) modes and by making the link with the disparate results of several famous and often‐quoted studies in the field, we can clarify this situation.

Dynamic object perception by pigeons: discrimination of action in video presentations

Two experiments examined the discrimination by pigeons of relative motion using computer-generated video stimuli. Using a go/no-go procedure, pigeons were tested with video stimuli in which the camera's perspective went either "around" or "through" an approaching object in a semi-realistic context. Experiment 1 found that pigeons could learn this discrimination and transfer it to videos composed from novel objects. Experiment 2 found that the order of the video's frames was critical to the discrimination of the videos. We hypothesize that the pigeons perceived a three-dimensional representation of the objects and the camera's relative motion and used this as the primary basis for discrimination. It is proposed that the pigeons might be able to form generalized natural categories for the different kinds of motions portrayed in the videos.

2000 Macromolecular Science and Engineering Award LectureThe versatility of azobenzene polymers

The well-known trans–cis–trans photoisomerization of azobenzenes produces at least three different kinds of motion in the polymer materials to which the azobenzenes are bound. The first is a photoinduced motion of the azobenzene groups only, and they can align in a selected position with respect to the light polarization. The second is a macroscopic motion of huge amounts of polymeric material, producing surface deformation, and the third is a reorganization of smectic domains in liquid crystalline polymers. These motions and their consequences are briefly discussed in relation to the polymer structure and some possible photonic applications are mentioned.Key words: photoinduced orientation, azobenzene polymers, surface gratings, photonics, thermochromism, photochromism, photorefractivity, photoinduced chirality and switching.

An examination of the distinction between nouns and verbs: Associations with two different kinds of motion

Four experiments provide evidence that people are biased to associate particular types of motion with nouns and different types of motion with verbs. Novel nouns and verbs were related to two types of motion: (1) path, or the direction of motion of one character with respect to the other character, and (2) movement orientation, or the direction a character was facing as it moved. Subjects associated verbs more strongly with path than with movement orientation. In contrast, they associated nouns more strongly with movement orientation than with path. Movement orientation was associated with both object categories and verbs, inconsistent with a complete division of labor between these two types of categories. These results are consistent, however, with the notion that people are biased to associate verbs with relations between objects, whereas they are biased to associate object categories with motions defined with respect to the object carrying out those motions.

Motion of an elliptical vortex under rotating strain: conditions for asymmetric merging

The analysis of the motion of a uniform vortex ( patch) of elliptical shape under a rotating strain field is employed to investigate the conditions leading to merging for two co-rotating elliptical patches of equal vorticity but different circulation. The motion of the patch having smaller circulation under the rotating strain field induced by the other vortex is analyzed, by considering both the intensity and the rotation rate of the strain constant. Under this assumption, we may adopt a first integral of motion which has been already used to discuss the different kinds of motion experienced by the elliptical patch. In the present paper, the dependence of the motion on the initial conditions and on the strain parameters is analyzed in further detail, to provide an overall picture of the elliptical patch dynamics. These results are employed in the analysis of the merging conditions. To this aim, the strain parameters, written in terms of the circulation of the larger vortex and of the distance between the two vortices, are kept frozen at their initial values. For a given circulation of the larger vortex and for a given vorticity and initial configuration of the smaller one, it is possible to find a particular distance between the vortices – transitional distance, d t – to which a significant change in the dynamics of the smaller elliptical patch is associated. It is always slightly lower than the critical distance and the difference between the two values decreases for vanishing size of the smaller vortex. The analysis of the first integral shows that, for an initial distance larger than d t, the motion of the vortex leads to small periodic variations of its second-order moment. On the contrary, when the distance is smaller than d t, the motion implies a large growth of its second-order moment, that is able to force the merging for frozen strain parameters.