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Relative motion

Nathalie Van Humbeeck, Tom Putzeys, Johan Wagemans
Two stimuli alternately presented at different locations can evoke a percept of a stimulus continuously moving between the two locations. The neural mechanism underlying this apparent motion (AM) is thought to be increased activation of primary visual cortex (V1) neurons tuned to locations along the AM path, although evidence remains inconclusive. AM masking, which refers to the reduced detectability of stimuli along the AM path, has been taken as evidence for AM-related V1 activation. AM-induced neural responses are thought to interfere with responses to physical stimuli along the path and as such impair the perception of these stimuli...
October 2016: PLoS Computational Biology
Jun Dang, Fang-Fang Yin, Tao You, Chunhua Dai, Deyu Chen, Jing Wang
PURPOSE: Current approaches using deformable vector field (DVF) for motion-compensated 4D-cone beam CT (CBCT) reconstruction typically utilize an isotropically smoothed DVF between different respiration phases. Such isotropically smoothed DVF does not work well if sliding motion exists between neighboring organs. This study investigated an anisotropic motion modeling scheme by extracting organ boundary local motions (e.g., sliding) and incorporated them into 4D-CBCT reconstruction to optimize the motion modeling and reconstruction methods...
October 2016: Medical Physics
R Tiani, L Rongy
The nonlinear dynamics of A + B → C fronts is analyzed both numerically and theoretically in the presence of Marangoni flows, i.e., convective motions driven by surface tension gradients. We consider horizontal aqueous solutions where the three species A, B, and C can affect the surface tension of the solution, thereby driving Marangoni flows. The resulting dynamics is studied by numerically integrating the incompressible Navier-Stokes equations coupled to reaction-diffusion-convection (RDC) equations for the three chemical species...
September 28, 2016: Journal of Chemical Physics
Yu Wang, Xiao Zheng, Jinlong Yang
Transition metal phthalocyanine molecules adsorbed on a metal substrate exhibit rich spin-related phenomena such as magnetic anisotropy, spin excitation, and Kondo effect. In this work, we investigate theoretically few-layer cobalt phthalocyanine (CoPc) molecular assembly stacking on Pb(111) surface with the use of a combined density functional theory (DFT) and hierarchical equations of motion (HEOM) approach. Calculation results indicate that the local spin properties of CoPc/Pb(111) composites depend critically on the number of adsorption layers...
October 21, 2016: Journal of Chemical Physics
Ioannis Skarmoutsos, Stefano Mossa, Jannis Samios
Molecular dynamics simulation studies were performed to investigate the structural and dynamic properties of liquid carbon disulfide (CS2) from ambient to elevated pressure conditions. The results obtained have revealed structural changes at high pressures, which are related to the more dense packing of the molecules inside the first solvation shell. The calculated neutron and X-ray structure factors have been compared with available experimental diffraction data, also revealing the pressure effects on the short-range structure of the liquid...
October 21, 2016: Journal of Chemical Physics
Christian Urban, Roberto Otero, David Écija, Marta Trelka, Nazario Martín, José M Gallego, Rodolfo Miranda
We have measured STM movies to study the diffusion of individual vacancies in a self-assembled layer of a tetrathiafulvalene derivative (exTTF) on Au(111) at room temperature. The diffusion is anisotropic, being faster along the compact direction of the molecular lattice. A detailed analysis of the anisotropic displacement distribution of the single vacancies shows that the relative abundance of double jumps (that is, the collective motion of molecular dimers) with respect to single jumps is rather large, the number of double jumps being more than 20% of the diffusion events...
October 21, 2016: Journal of Chemical Physics
Kirill Bobrov, Nataliya Kalashnyk, Laurent Guillemot
We present a room temperature STM study of perylene adsorption on Ag(110) at the monolayer coverage regime. We found that structure and symmetry of the perylene monolayer are settled by thermodynamic balance of the three factors: (i) the ability of perylene molecules to recognize specific adsorption sites on the (110) lattice, (ii) the intermolecular interaction, and (iii) the accommodation of thermal motion of the molecules. The moderate strength of the site recognition and the intermolecular interaction, of the same order of magnitude as kT ∼ 25 meV, represents a key feature of the thermodynamic balance...
October 21, 2016: Journal of Chemical Physics
Harro R Dittmar, Peter G Kusalik
As shown previously, it is possible to apply configurational and kinetic thermostats simultaneously in order to induce a steady thermal flux in molecular dynamics simulations of many-particle systems. This flux appears to promote motion along potential gradients and can be utilized to enhance the sampling of ordered arrangements, i.e., it can facilitate the formation of a critical nucleus. Here we demonstrate that the same approach can be applied to molecular systems, and report a significant enhancement of the homogeneous crystal nucleation of a carbon dioxide (EPM2 model) system...
October 7, 2016: Journal of Chemical Physics
I Santamaría-Holek, A Pérez-Madrid
The distinction between the damping coefficient and the effective non-linear mobility of driven particles in active micro-rheology of supercooled liquids is explained in terms of individual and collective dynamics. The effective mobility arises as a collective effect which gives insight into the energy landscape of the system. On the other hand, the damping coefficient is a constant that modulates the effect of external forces over the thermal energy which particles have at their disposition to perform Brownian motion...
October 7, 2016: Journal of Chemical Physics
Naoya Fujiwara, Jürgen Kurths, Albert Díaz-Guilera
We study synchronization of systems in which agents holding chaotic oscillators move in a two-dimensional plane and interact with nearby ones forming a time dependent network. Due to the uncertainty in observing other agents' states, we assume that the interaction contains a certain amount of noise that turns out to be relevant for chaotic dynamics. We find that a synchronization transition takes place by changing a control parameter. But this transition depends on the relative dynamic scale of motion and interaction...
September 2016: Chaos
Abhishek Banerjee, Arnab Dey, Narayanan Chandrakumar
Solution-state Overhauser dynamic nuclear polarization (ODNP) at moderate fields, performed by saturating the electron spin resonance (ESR) of a free radical added to the sample of interest, is well known to lead to significant NMR signal enhancements in the steady state, owing to electron-nuclear cross-relaxation. Here it is shown that under conditions which limit radical access to the molecules of interest, the time course of establishment of ODNP can provide a unique window into internuclear cross-relaxation, and reflects relatively slow molecular motions...
October 26, 2016: Angewandte Chemie
R Oates, A Brown, A Tan, F Foroudi, M Lim Joon, M Schneider, A Herschtal, T Kron
AIMS: To investigate a relationship between maximum rectal diameter (MRD) on pre-treatment cone beam computed tomography (CBCT) and intra-fraction prostate motion, in the context of an adaptive image-guided radiotherapy (IGRT) method. MATERIALS AND METHODS: The MRD was measured on 2125 CBCTs from 55 retrospective patient datasets and related to prostate displacement from intra-fraction imaging. A linear regression model was developed to determine a threshold MRD associated with a high probability of small prostate displacement...
October 22, 2016: Clinical Oncology: a Journal of the Royal College of Radiologists
Panagiotis Kousoulis, Athanasios Pantes, Georgios Alevetsovitis, Ourania Fydanaki
INTRODUCTION: The Motion Sickness Assessment Questionnaire (MSAQ) was developed in order to assess the multiple dimensions of the motion sickness syndrome (gastrointestinal, central nervous system, peripheral, and sopite-related symptoms). The aim of this study was to evaluate the psychometric properties of the Greek version of the MSAQ. METHODS: The MSAQ was translated into Greek and then translated back into English. Minor differences between the two texts were corrected...
2016: Aerospace Medicine and Human Performance
Michael Hanke, Nico Adelhöfer, Daniel Kottke, Vittorio Iacovella, Ayan Sengupta, Falko R Kaule, Roland Nigbur, Alexander Q Waite, Florian Baumgartner, Jörg Stadler
Here we present an update of the studyforrest ( dataset that complements the previously released functional magnetic resonance imaging (fMRI) data for natural language processing with a new two-hour 3 Tesla fMRI acquisition while 15 of the original participants were shown an audio-visual version of the stimulus motion picture. We demonstrate with two validation analyses that these new data support modeling specific properties of the complex natural stimulus, as well as a substantial within-subject BOLD response congruency in brain areas related to the processing of auditory inputs, speech, and narrative when compared to the existing fMRI data for audio-only stimulation...
October 25, 2016: Scientific Data
Mostafa Fakhraee, Mohammad Reza Gholami
The effects of ester addition on structural and dynamic properties of biodegradable ILs composed of the 1-(alkoxycarbonyl)-3-alkylimidazolium cation ([C1COOCnC1im](+), n = 1, 2, 4) coupled with [Br](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) are explored using the molecular dynamics (MD) simulations and quantum theory of atoms in molecules (QTAIM) at 400 K. Formation of the intramolecular H bonds between O atoms of the ester group and H atoms of the imidazolium ring as well as the nearest H atom of the alkyl chain to the ester group are disclosed from reduced density gradient (RDG) results...
October 25, 2016: Journal of Physical Chemistry. B
Kristen L Kucera, Karen G Roos, Jennifer M Hootman, Hester J Lipscomb, John M Dement, Barbara A Silverstein
BACKGROUND: Little is known about the work-related injury and illnesses experienced by certified athletic trainers (AT). METHODS: The incidence and characteristics of injury/illness claims filed in two workers' compensation systems were described from 2001 to 2011. Yearly populations at risk were estimated from National Athletic Trainers' Association membership statistics. Incidence rate ratios (IRR) were reported by job setting. RESULTS: Claims were predominantly for traumatic injuries and disorders (82...
October 24, 2016: American Journal of Industrial Medicine
Behnoosh Parsa, Vladimir M Zatsiorsky, Mark L Latash
We address the nature of unintentional changes in performance in two papers. This second paper tested hypotheses related to stability of task-specific performance variables estimated using the framework of the uncontrolled manifold (UCM) hypothesis. Our first hypothesis was that selective stability of performance variables would be observed even when the magnitudes of those variables drifted unintentionally because of the lack of visual feedback. Our second hypothesis was that stability of a variable would depend on the number of explicit task constraints...
October 24, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Bo-Kyu Yang, Seung-Rim Yi, Young-Joon Ahn, Se-Hyuk Im, Sang-Hyun Park
Fatigue fracture of the pelvis is the form of fracture due to repetitive micro-stress accumulation, can be affected by a number of factors such as patient's nutritional status, biomechanics, social status and so on. Still there is no study about precise standard degree of external force that lead to stress fracture, but it may caused by compression force, traction force or complex force and others. Avulsion stress to ischial tuberosity or anterior superior iliac spine by attached muscle is known as the main factor for the avulsion fracture...
September 2016: Hip Pelvis
Sanjeev Kakar, Ryan E Breighner, Shuai Leng, Cynthia H McCollough, Steven L Moran, Richard A Berger, Kristin D Zhao
Background Scapholunate (SL) interosseus ligament injuries detected at an early stage could allow the surgeon to prevent progression through the spectrum of injury that leads to instability, and eventually osteoarthritis. We contend that early instability following injury can be detected by visualizing the relative motions and distances between the involved carpal bones (scaphoid and lunate) during wrist movement in vivo. The purpose of this study is to demonstrate the utility of dynamic CT (i.e., 4DCT) in diagnosing SL interosseus ligament injuries in two patients with clinical suspicion of SL interosseus ligament injury during flexion-extension (FE), radial-ulnar (RU) deviation, and dart thrower's (DT) motions...
November 2016: Journal of Wrist Surgery
Lauren L Drogos, Stephanie J Gill, Amanda V Tyndall, Jill K Raneri, Jillian S Parboosingh, Aileen Naef, Kyle D Guild, Gail Eskes, Patrick J Hanly, Marc J Poulin
BACKGROUND: It has been estimated that the prevalence of Alzheimer disease (AD) and related dementias will triple by 2035, unless effective interventions or treatments are found for the neurodegenerative disease. Understanding sleep changes as a marker for both AD risk and progression is a burgeoning area of investigation. Specifically, there is emerging evidence that both sleep disturbances and the APOE ε4 allele are associated with increased dementia risk. Previous research has suggested that in AD, individuals carrying the APOE ε4 allele have decreased sleep quality compared to individuals without the APOE ε4 allele...
October 25, 2016: Neurology
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