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Adaptive motion

Andreas Fehlner, Sebastian Hirsch, Martin Weygandt, Thomas Christophel, Eric Barnhill, Mykola Kadobianskyi, Jürgen Braun, Johannes Bernarding, Ralf Lützkendorf, Ingolf Sack, Stefan Hetzer
PURPOSE: To improve the resolution of elasticity maps by adapting motion and distortion correction methods for phase-based magnetic resonance imaging (MRI) contrasts such as magnetic resonance elastography (MRE), a technique for measuring mechanical tissue properties in vivo. MATERIALS AND METHODS: MRE data of the brain were acquired with echo-planar imaging (EPI) at 3T (n = 14) and 7T (n = 18). Motion and distortion correction parameters were estimated using the magnitude images...
October 20, 2016: Journal of Magnetic Resonance Imaging: JMRI
Andrei V Nikitin, Michael Rey, Alena Alexandrovna Rodina, Balasubramoniam Murali Krishna, Vladimir G Tyuterev
Nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) of the germane molecule are constructed using extended ab initio CCSD(T) calculations at 19882 points. PES analytical representation is determined as an expansion in non-linear symmetry adapted products of orthogonal and internal coordinates involving 340 parameters up to 8th order. Minor empirical refinement of the equilibrium geometry and of four quadratic parameters of the PES computed at the CCSD(T) / aug-cc-pVQZ-DK level of the theory yielded the accuracy below 1 cm-1 for all experimentally known vibrational band centers of five stable isotopologues of 70GeH4, 72GeH4, 73GeH4, 74GeH4 and 76GeH4 up to 8300 cm-1...
October 20, 2016: Journal of Physical Chemistry. A
Rodrigo S Maeda, Shawn M O'Connor, J Maxwell Donelan, Daniel S Marigold
As we walk, we must accurately place our feet to stabilize our motion and to navigate our environment. We must also achieve this accuracy despite imperfect sensory feedback and unexpected disturbances. Here we tested whether the nervous system uses state estimation to beneficially combine sensory feedback with forward model predictions to compensate for these challenges. Specifically, subjects wore prism lenses during a visually guided walking task, and we used trial-by-trial variation in prism lenses to add uncertainty to visual feedback and induce a reweighting of this input...
October 19, 2016: Journal of Neurophysiology
David P McGovern, Kevin S Walsh, Jason Bell, Fiona N Newell
Both spatial and temporal context influence our perception of visual stimuli. For instance, both nearby moving stimuli and recently viewed motion can lead to biases in the perceived direction of a moving stimulus. Due to similarities in the spatial tuning properties of these spatial and temporal context-dependent effects, it is often assumed that they share a functional goal in motion processing and arise from common neural mechanisms. However, the psychophysical evidence concerning this assumption is inconsistent...
October 17, 2016: Vision Research
Enrico Agabiti Rosei
Current Hypertension Guidelines emphasize the importance of assessing the presence of preclinical organ damage. In fact, an extensive evaluation of organ damage may increase the number of patients classified at high CV risk and therefore strongly influence the clinical management of patients. Hypertensive heart disease remains to date the form of organ damage for which there is the greatest amount of evidence of a strong independent prognostic significance. In the presence of a chronic pressure overload, a parallel addition of sarcomers takes place with an increase in myocyte width, which in turn increases left ventricular wall thickness; myocyte hypertrophy is also associated with apoptosis, collagen deposition and ventricular fibrosis with an impairment of coronary hemodynamics as well, thus profoundly influencing functional properties of the left (and right) ventricle...
September 2016: Journal of Hypertension
Cheng-Shiu Chung, Hongwu Wang, Matthew J Hannan, Dan Ding, Annmarie R Kelleher, Rory A Cooper
OBJECTIVE: The objectives of this study were to evaluate the performance of commercially available assistive robotic manipulators (ARMs) user interfaces and to investigate the concurrent validity and sensitivity to change with task-oriented performance evaluation tools (TO-PETs) for ARMs. DESIGN: This was a nonblinded randomized controlled study with power-wheelchair users with upper-extremity impairments (N = 10). Participants were trained to use 2 ARMs with their respective original user interfaces (keypad and joystick) and evaluated the performance using TO-PET and the adapted Wolf Motor Function Test (WMFT-ARM)...
October 6, 2016: American Journal of Physical Medicine & Rehabilitation
Nicola Rossi, Floris R Braakman, Davide Cadeddu, Denis Vasyukov, Gözde Tütüncüoglu, Anna Fontcuberta I Morral, Martino Poggio
Self-assembled nanowire (NW) crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW's flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Here, taking advantage of its adaptability as a scanning probe, we use a single NW to image a sample surface...
October 17, 2016: Nature Nanotechnology
Maria J S Guerreiro, Lisa Putzar, Brigitte Röder
Recent neuroimaging studies have demonstrated that a brief period of congenital blindness induces long-lasting reorganization within the visual cortex of sight-recovery humans [1, 2]. However, the behavioral consequences of this cross-modal reorganization are not yet known. Here we investigated this question by examining the transfer of motion aftereffects across the visual and auditory modalities within six individuals who had been born blind due to dense bilateral cataracts and regained sight when they were treated at 5-24 months of age...
October 1, 2016: Current Biology: CB
Amy Yuan, Jie Wei, Carl P Gaebler, Hailiang Huang, Devin Olek, Guang Li
PURPOSE: To develop a physical, adaptive motion perturbation model to predict tumor motion using feedback from dynamic measurement of breathing conditions to compensate for breathing irregularities. METHODS AND MATERIALS: A novel respiratory motion perturbation (RMP) model was developed to predict tumor motion variations caused by breathing irregularities. This model contained 2 terms: the initial tumor motion trajectory, measured from 4-dimensional computed tomography (4DCT) images, and motion perturbation, calculated from breathing variations in tidal volume (TV) and breathing pattern (BP)...
September 3, 2016: International Journal of Radiation Oncology, Biology, Physics
Corey Pew, Glenn K Klute
Amputees often experience soft tissue breakdown and discomfort from the high transverse plane shear stresses between the residual limb and prosthesis. To evaluate the effects of varying the transverse plane stiffness, a small sample population of lower limb amputees wore a novel variable stiffness torsion adapter (VSTA). Peak transverse plane moments were evaluated for three fixed stiffness levels (compliant: 0.30Nm/°, intermediate: 0.57Nm/°, stiff: 0.91Nm/°) while participants traversed five tasks of daily living that emphasize transverse plane motion including: straight walking for reference, 90° turns, 180° turns, a static reach test, and the L-Test of functional mobility...
October 4, 2016: Gait & Posture
Nikolai Blanik, Konrad Heimann, Carina Pereira, Michael Paul, Vladimir Blazek, Boudewijn Venema, Thorsten Orlikowsky, Steffen Leonhardt
Vital parameter monitoring of term and preterm infants during incubator care with self-adhesive electrodes or sensors directly positioned on the skin [e.g. photoplethysmography (PPG) for oxygen saturation or electrocardiography (ECG)] is an essential part of daily routine care in neonatal intensive care units. For various reasons, this kind of monitoring contains a lot of stress for the infants. Therefore, there is a need to measure vital parameters (for instance respiration, temperature, pulse, oxygen saturation) without mechanical or conductive contact...
October 15, 2016: Biomedizinische Technik. Biomedical Engineering
Feng Liu, An Tai, Ergun Ahunbay, Elizabeth Gore, Candice Johnstone, X Allen Li
PURPOSE: To quantify interfractional independent motions between multiple primary targets in radiation therapy (RT) of lung cancer and to study the dosimetric benefits of an online adaptive replanning method to account for these variations. METHODS AND MATERIALS: Ninety-five on-treatment diagnostic-quality computed tomography (CT) scans acquired for 9 lung cancer patients treated with image-guided RT (IGRT) using a CT-on-rails (CTVision, Siemens) were analyzed. On each on-treatment CT set, contours of the targets (gross tumor volume, clinical target volume, or involved nodes), and organs at risk were generated by populating the planning contours using an autosegmentation tool (ABAS, Elekta) with manual editing...
September 2, 2016: Practical Radiation Oncology
Stefania Brocca, Cristian Ferrari, Alberto Barbiroli, Alessandra Pesce, Marina Lotti, Marco Nardini
Life in cold environments requires an overall increase in the flexibility of macromolecular and supramolecular structures to allow biological processes to take place at low temperature. Conformational flexibility supports high catalytic rates of enzymes in the cold but in several cases is also a cause of instability. The three-dimensional structure of the psychrophilic acyl aminoacyl peptidase from Sporosarcina psychrophila (SpAAP) reported in this paper highlights adaptive molecular changes resulting in a fine-tuned trade-off between flexibility and stability...
October 14, 2016: FEBS Journal
Adama Creppy, Franck Plouraboué, Olivier Praud, Xavier Druart, Sébastien Cazin, Hui Yu, Pierre Degond
New experimental evidence of self-motion of a confined active suspension is presented. Depositing fresh semen sample in an annular shaped microfluidic chip leads to a spontaneous vortex state of the fluid at sufficiently large sperm concentration. The rotation occurs unpredictably clockwise or counterclockwise and is robust and stable. Furthermore, for highly active and concentrated semen, richer dynamics can occur such as self-sustained or damped rotation oscillations. Experimental results obtained with systematic dilution provide a clear evidence of a phase transition towards collective motion associated with local alignment of spermatozoa akin to the Vicsek model...
October 2016: Journal of the Royal Society, Interface
Marie Bagger Bohn, Annemette Krintel Petersen, Dennis Brandborg Nielsen, Henrik Sørensen, Martin Lind
BACKGROUND: Anterior cruciate ligament (ACL) deficiency leads to altered stability of the knee. The purpose of this study was to compare the dynamic, rotational stability of the knee, expressed as rotational stiffness, between anterior cruciate ligament-deficient (ACLD) knees, their contralateral intact knees (ACLI) and a knee healthy control group during walking, running and 90° pivoting. We hypothesized a larger tibial internal rotation, a smaller knee joint external moment and a lower rotational stiffness in the ACLD group compared to the ACLI and the control group...
December 2016: Journal of Experimental Orthopaedics
Ye Zhang, Isabel Huth, Martin Wegner, Damien Charles Weber, Antony John Lomax
BACKGROUND AND PURPOSE: The treatment quality of pencil beam scanned (PBS) proton therapy to mobile tumour treatments can be compromised due to interplay effects. The aim of this work is to systematically evaluate the effectiveness of rescanning for liver tumour treatments for a commercial PBS delivery system. MATERIALS AND METHODS: Plans were calculated to patient specific ITV's (2GyRBE), using spot spacings of 4 and 8mm for 1- and 3-field plans. 4D dose calculations were performed using regular and irregular motion extracted from nine 4DCT(MRI) liver datasets with 4 different starting phases...
October 7, 2016: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
Joel Pearson, Rocco Chiou, Sebastian Rogers, Marcus Wicken, Stewart Heitmann, Bard Ermentrout
Hallucinations occur in both normal and clinical populations. Due to their unpredictability and complexity, the mechanisms underlying hallucinations remain largely untested. Here we show that visual hallucinations can be induced in the normal population by visual flicker, limited to an annulus that constricts content complexity to simple moving grey blobs, allowing objective mechanistic investigation. Hallucination strength peaked at ~11 Hz flicker and was dependent on cortical processing. Hallucinated motion speed increased with flicker rate, when mapped onto visual cortex it was independent of eccentricity, underwent local sensory adaptation and showed the same bistable and mnemonic dynamics as sensory perception...
October 11, 2016: ELife
Gaurav Jerath, Prakash Kishore Hazam, Shashi Shekhar, Vibin Ramakrishnan
Polypeptide chain has an invariant main-chain and a variant side-chain sequence. How the side-chain sequence determines fold in terms of its chemical constitution has been scrutinized extensively and verified periodically. However, a focussed investigation on the directive effect of side-chain geometry may provide important insights supplementing existing algorithms in mapping the geometrical evolution of protein chains and its structural preferences. Geometrically, folding of protein structure may be envisaged as the evolution of its geometric variables: ϕ, and ψ dihedral angles of polypeptide main-chain directed by χ1, and χ2 of side chain...
2016: PloS One
Alexandra J Burgess, Renata Retkute, Simon P Preston, Oliver E Jensen, Michael P Pound, Tony P Pridmore, Erik H Murchie
Physical perturbation of a plant canopy brought about by wind is a ubiquitous phenomenon and yet its biological importance has often been overlooked. This is partly due to the complexity of the issue at hand: wind-induced movement (or mechanical excitation) is a stochastic process which is difficult to measure and quantify; plant motion is dependent upon canopy architectural features which, until recently, were difficult to accurately represent and model in 3-dimensions; light patterning throughout a canopy is difficult to compute at high-resolutions, especially when confounded by other environmental variables...
2016: Frontiers in Plant Science
J E Herbert-Read
Moving animal groups display remarkable feats of coordination. This coordination is largely achieved when individuals adjust their movement in response to their neighbours' movements and positions. Recent advancements in automated tracking technologies, including computer vision and GPS, now allow researchers to gather large amounts of data on the movements and positions of individuals in groups. Furthermore, analytical techniques from fields such as statistical physics now allow us to identify the precise interaction rules used by animals on the move...
October 1, 2016: Journal of Experimental Biology
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