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https://www.readbyqxmd.com/read/28817289/how-to-drive-a-flashing-electron-ratchet-to-maximize-current
#1
Ofer Kedem, Bryan Lau, Emily A Weiss
Biological systems utilize a combination of asymmetry, noise, and chemical energy to produce motion in the highly damped environment of the cell with molecular motors, many of which are "ratchets", non-equilibrium devices for producing directed transport using non-directional perturbations, without a net bias. The underlying ratchet principle has been implemented in man-made micro- and nano-devices, to transport charged particles by oscillating an electric potential with repeating asymmetric features. In this experimental study, the ratcheting of electrons in an organic semiconductor is optimized by tuning the temporal modulation of the oscillating potential, applied using nanostructured electrodes...
August 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/28817196/technical-note-quantitative-analysis-of-ivim-diffusion-mri-using-total-variation-and-huber-penalty-function
#2
Esha Baidya Kayal, Devasenathipathy Kandasamy, Kedar Khare, Jayendra Tiru Alampally, Sameer Bakhshi, Raju Sharma, Amit Mehndiratta
PURPOSE: Quantitative analysis in Intra-voxel Incoherent Motion (IVIM) imaging commonly uses voxel-wise estimation of the bi-exponential model, which might not be reliable for clinical interpretation. Improving model fitting performance and qualitative and quantitative parametric estimation, two novel methodologies are proposed here. METHODS: Five IVIM analyses methodologies: i) Bi-Exponential (BE) model, ii) Segmented BE method with 2-parameter fitting (BEseg-2), iii) Segmented BE method with 1-parameter fitting (BEseg-1), iv) BE with adaptive Total Variation Penalty function (BE+TV) and v) BE with adaptive Huber Penalty function (BE+HPF) were evaluated...
August 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28816345/errors-in-calculating-a-p-tibial-contact-locations-in-total-knee-arthroplasty-using-3d-model-to-2d-image-registration-in-radiographs-an-in-vitro-study-of-two-methods
#3
Derrick Ross, Stephen Howell, Maury Hull
Knowledge of A-P tibial contact locations provides an objective assessment of the relative motion of the tibia on the femur following total knee arthroplasty, which can be used to compare the effects of different components, surgical techniques, and alignment goals on knee function in vivo. Both the closest point method and the penetration method have been used to calculate A-P tibial contact locations using 3D model-to-2D image registration. Because the errors in calculating the A-P tibial contact locations using these two methods are unknown, the primary purpose of this study was to determine these errors...
August 17, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28816159/consensus-guidelines-for-implementing-pencil-beam-scanning-proton-therapy-for-thoracic-malignancies-on-behalf-of-the-ptcog-thoracic-and-lymphoma-subcommittee
#4
REVIEW
Joe Y Chang, Xiaodong Zhang, Antje Knopf, Heng Li, Shinichiro Mori, Lei Dong, Hsiao-Ming Lu, Wei Liu, Shahed N Badiyan, Stephen Both, Arturs Meijers, Liyong Lin, Stella Flampouri, Zuofeng Li, Kikuo Umegaki, Charles B Simone, Xiaorong R Zhu
Pencil-beam scanning (PBS) proton therapy (PT), particularly intensity modulated PT, represents the latest advanced PT technology for treating cancers, including thoracic malignancies. On the basis of virtual clinical studies, PBS-PT appears to have great potential in its ability to tightly tailor the dose to the target while sparing critical structures, thereby reducing treatment-related toxicities, particularly for tumors in areas with complicated anatomy. However, implementing PBS-PT for moving targets has several additional technical challenges compared with intensity modulated photon radiation therapy or passive scattering PT...
September 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28816151/quantification-of-pediatric-abdominal-organ-motion-with-a-4-dimensional-magnetic-resonance-imaging-method
#5
Jinsoo Uh, Matthew J Krasin, Yimei Li, Xingyu Li, Christopher Tinkle, John T Lucas, Thomas E Merchant, Chiaho Hua
PURPOSE: To characterize respiration-induced abdominal organ motion in children receiving radiation treatment with a 4-dimensional (4D) magnetic resonance imaging (MRI) method. METHODS AND MATERIALS: We analyzed free-breathing coronal 4D MRI datasets acquired from 35 patients (aged 1-20 years) with abdominal tumors. A deformable image registration of the 4D MRI datasets was performed to derive motion trajectories of selected anatomic landmarks, from which organ motions were quantified...
September 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28815808/intravoxel-incoherent-motion-diffusion-weighted-imaging-in-assessing-bladder-cancer-invasiveness-and-cell-proliferation
#6
Fang Wang, Lian-Ming Wu, Xiao-Lan Hua, Zi-Zhou Zhao, Xiao-Xi Chen, Jian-Rong Xu
BACKGROUND: Nonmuscle-invasive bladder cancer (NMIBC, Stage T1 or lower) is treated with transurethral resection (TUR), while muscle-invasive bladder cancer (MIBC, Stage T2 or more) requires neoadjuvant chemotherapy before radical cystectomy. Hence, preoperative differentiation is vital. PURPOSE: To investigate whether intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) can differentiate NMIBC from MIBC and to assess whether there were correlations between IVIM parameters and the Ki-67 labeling index (LI)...
August 17, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28814637/asymmetric-vestibular-stimulation-reveals-persistent-disruption-of-motion-perception-in-unilateral-vestibular-lesions
#7
Roberto Panichi, Mario Faralli, Rosa Bruni, Artemis Kiriakarely, Chiara Occhigrossi, Aldo Ferraresi, Adolfo M Bronstein, Vito Enrico Pettorossi
Self-motion perception was studied in patients with unilateral vestibular lesions (UVL) due to acute vestibular neuritis at 1 week, 4, 8 and 12 months after the acute episode. We assessed vestibularly-mediated self-motion perception by measuring the error in reproducing the position of a remembered visual target at the end of 4 cycles of asymmetric whole-body rotation. The oscillatory stimulus consists of a slow (0.09Hz) and a fast (0.38Hz) half cycle. A large error was present in UVL patients when the slow half cycle was delivered towards the lesion side, but minimal towards the healthy side...
August 16, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28814635/perception-of-the-dynamic-visual-vertical-during-sinusoidal-linear-motion
#8
Antonella Pomante, Luc P J Selen, W Pieter Medendorp
The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravito-inertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely...
August 16, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28814021/simultaneous-estimation-of-human-and-exoskeleton-motion-a-simplified-protocol
#9
M T Alvarez, D Torricelli, A J Del-Ama, D Pinto, J Gonzalez-Vargas, J C Moreno, A Gil-Agudo, J L Pons
Adequate benchmarking procedures in the area of wearable robots is gaining importance in order to compare different devices on a quantitative basis, improve them and support the standardization and regulation procedures. Performance assessment usually focuses on the execution of locomotion tasks, and is mostly based on kinematic-related measures. Typical drawbacks of marker-based motion capture systems, gold standard for measure of human limb motion, become challenging when measuring limb kinematics, due to the concomitant presence of the robot...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813990/a-learning-based-agent-for-home-neurorehabilitation
#10
Andreas Lydakis, Yuanliang Meng, Christopher Munroe, Yi-Ning Wu, Momotaz Begum
This paper presents the iterative development of an artificially intelligent system to promote home-based neurorehabilitation. Although proper, structured practice of rehabilitation exercises at home is the key to successful recovery of motor functions, there is no home-program out there which can monitor a patient's exercise-related activities and provide corrective feedback in real time. To this end, we designed a Learning from Demonstration (LfD) based home-rehabilitation framework that combines advanced robot learning algorithms with commercially available wearable technologies...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813988/capturing-prosthetic-socket-fitment-preliminary-results-using-an-ultrasound-based-device
#11
Andrew K LaPre, Vinh Q Nguyen, Ulvi Baspinar, Michael White, Frank C Sup
The acceptance of advanced prosthetic systems by users requires overcoming unique challenges of fitting prostheses to unique user anatomies to achieve systematic performance across a user base. Variations among individuals introduce complexities in fitting the sockets. Due to the difficulty of measuring socket interface characteristics, there is a lack of quantifiable diagnostic fitment information available. As a result, the process of fitting sockets is currently a laborintensive, manual approach, and can often result in sockets that are uncomfortable, unstable, or impede full range of motion...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813980/human-mimetic-forearm-mechanism-towards-bionic-arm
#12
Minsang Seo, Hogyun Kim, Youngjin Choi
The paper presents a mechanical forearm mechanism to extend the pronation and supination (P/S) movement of the trans-radial amputee when he/she is able to conduct the P/S motion partially with his/her remaining forearm. The P/S motions of the existing prostheses and robotic arms developed till now are completely different from those of the human. When we are to develop the robotic prostheses for the amputees, two important issues should be considered such as cosmetic issue to look like normal arm and motion harmony issue between robotic prosthesis and the amputated living arm...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813972/novel-ankle-orthosis-with-elastomer-embedded-flexible-joint
#13
Takehito Kikuchi, Kohei Ishiya, Isao Abe, Sosuke Tanida, Takashi Yasuda
In this study, we propose a new ankle orthosis with elastomer-embedded flexible joints (EEFJ), composed of C-shaped springs and 3D-printed circular elastomer. This orthosis was designed to reduce burden on the tibialis anterior muscle (TA) and to achieve clearance between the tip of the toe and the ground. Fabrication method, strength testing, and gait analysis were conducted. According to the results of strength testing, the combination of the C-spring with 0.3 mm and 0.5 mm thickness and the elastomer with 30% and 60% filling density performs a supporting torque of 0...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813949/monitoring-brain-potentials-to-guide-neurorehabilitation-of-tracking-impairments
#14
Boris Yazmir, Miriam Reiner
Motor impairments come in different forms. One class of motor impairments, relates to accuracy of tracking a moving object, as, for instance, when chasing in an attempt to catch it. Here we look at neural signals associated with errors in tracking, and the implications for brain-computer-interfaces that target impairment-tailored rehabilitation. As a starting point, we characterized EEG signals evoked by tracking errors during continuous natural motion, in healthy participants. Participants played a virtual 3D, ecologically valid haptic tennis game, and had to track a moving tennis ball in order to hit and send the ball towards the opponent's court...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813947/exploiting-kinematic-constraints-to-compensate-magnetic-disturbances-when-calculating-joint-angles-of-approximate-hinge-joints-from-orientation-estimates-of-inertial-sensors
#15
Daniel Laidig, Thomas Schauer, Thomas Seel
Inertial Measurement Units (IMUs) have become a widely used tool for rehabilitation and other application domains in which human motion is analyzed using an ambulatory or wearable setup. Since the magnetic field is inhomogeneous in indoor environments and in the proximity of ferromagnetic material, standard orientation estimation and joint angle calculation algorithms often lead to inaccurate or even completely wrong results. One approach to circumvent this is to exploit the kinematic constraint that is induced by mechanical hinge joints and also by approximate hinge joints such as the knee joint and the finger (interphalangeal) joints of the human body...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813938/online-sparse-gaussian-process-based-human-motion-intent-learning-for-an-electrically-actuated-lower-extremity-exoskeleton
#16
Yi Long, Zhi-Jiang Du, Chao-Feng Chen, Wei Dong, Wei-Dong Wang
The most important step for lower extremity exoskeleton is to infer human motion intent (HMI), which contributes to achieve human exoskeleton collaboration. Since the user is in the control loop, the relationship between human robot interaction (HRI) information and HMI is nonlinear and complicated, which is difficult to be modeled by using mathematical approaches. The nonlinear approximation can be learned by using machine learning approaches. Gaussian Process (GP) regression is suitable for high-dimensional and small-sample nonlinear regression problems...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813905/design-and-characterization-of-the-openwrist-a-robotic-wrist-exoskeleton-for-coordinated-hand-wrist-rehabilitation
#17
Evan Pezent, Chad G Rose, Ashish D Deshpande, Marcia K O'Malley
Robotic devices have been clinically verified for use in long duration and high intensity rehabilitation needed for motor recovery after neurological injury. Targeted and coordinated hand and wrist therapy, often overlooked in rehabilitation robotics, is required to regain the ability to perform activities of daily living. To this end, a new coupled hand-wrist exoskeleton has been designed. This paper details the design of the wrist module and several human-related considerations made to maximize its potential as a coordinated hand-wrist device...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813902/hybrid-position-and-orientation-tracking-for-a-passive-rehabilitation-table-top-robot
#18
K K Wojewoda, P R Culmer, J F Gallagher, A E Jackson, M C Levesley
This paper presents a real time hybrid 2D position and orientation tracking system developed for an upper limb rehabilitation robot. Designed to work on a table-top, the robot is to enable home-based upper-limb rehabilitative exercise for stroke patients. Estimates of the robot's position are computed by fusing data from two tracking systems, each utilizing a different sensor type: laser optical sensors and a webcam. Two laser optical sensors are mounted on the underside of the robot and track the relative motion of the robot with respect to the surface on which it is placed...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813885/the-effect-of-robot-dynamics-on-smoothness-during-wrist-pointing
#19
Andrew Erwin, Evan Pezent, Joshua Bradley, Marcia K O'Malley
The improvement of movement smoothness over the course of therapy is one of the positive outcomes observed during robotic rehabilitation. Although movements are generally robust to disturbances, certain perturbations might disrupt an individual's ability to produce these smooth movements. In this paper, we explore how a rehabilitation robot's inherent dynamics impact movement smoothness during pointing tasks. Able-bodied participants made wrist pointing movements under four different operating conditions. Despite the relative transparency of the device, inherent dynamic characteristics negatively impacted movement smoothness...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813881/simulation-of-variable-impedance-as-an-intervention-for-upper-extremity-motor-exploration
#20
Felix C Huang
Current methods in robot-assisted therapy are limited in providing predictions of the effectiveness of interventions. Our approach focuses on how robotic interaction can impact the distribution of movements expressed in the arm. Using data from a previous study with stroke survivors (n=10), we performed simulations to examine how changes in hand endpoint impedance would alter exploratory motion. We present methods for designing a custom training intervention, by relating the desired change in acceleration covariance in planar motion with a corresponding change in inertia matrix...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
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