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https://www.readbyqxmd.com/read/28106190/nonadiabatic-photodynamics-and-uv-absorption-spectrum-of-all-trans-octatetraene
#1
Igor Lyskov, Horst Köppel, Christel M Marian
The short-time molecular quantum dynamics of all-trans-octatetraene after electronic excitation to the first bright valence state is theoretically investigated. A semiempirical approach of a multireference configuration interaction based on density functional theory, the so called hybrid DFT/MRCI, in both its original and redesigned formulations, is used for treating the electronic part of the problem. The nuclear kinetic part is defined with the help of symmetry-adapted internal coordinates also suitable for a large amplitude displacement...
January 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28105953/a-powered-prosthetic-ankle-joint-for-walking-and-running
#2
Martin Grimmer, Matthew Holgate, Robert Holgate, Alexander Boehler, Jeffrey Ward, Kevin Hollander, Thomas Sugar, André Seyfarth
BACKGROUND: Current prosthetic ankle joints are designed either for walking or for running. In order to mimic the capabilities of an able-bodied, a powered prosthetic ankle for walking and running was designed. A powered system has the potential to reduce the limitations in range of motion and positive work output of passive walking and running feet. METHODS: To perform the experiments a controller capable of transitions between standing, walking, and running with speed adaptations was developed...
December 19, 2016: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28105945/assessment-of-transfemoral-amputees-using-a-passive-microprocessor-controlled-knee-versus-an-active-powered-microprocessor-controlled-knee-for-level-walking
#3
Veerle Creylman, Ingrid Knippels, Paul Janssen, Evelyne Biesbrouck, Knut Lechler, Louis Peeraer
BACKGROUND: In transfemoral (TF) amputees, the forward propulsion of the prosthetic leg in swing has to be mainly carried out by hip muscles. With hip strength being the strongest predictor to ambulation ability, an active powered knee joint could have a positive influence, lowering hip loading and contributing to ambulation mobility. To assess this, gait of four TF amputees was measured for level walking, first while using a passive microprocessor-controlled prosthetic knee (P-MPK), subsequently while using an active powered microprocessor-controlled prosthetic knee (A-MPK)...
December 19, 2016: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#4
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102342/neural-activity-in-the-dorsal-medial-superior-temporal-area-of-monkeys-represents-retinal-error-during-adaptive-motor-learning
#5
Aya Takemura, Tomoyo Ofuji, Kenichiro Miura, Kenji Kawano
To adapt to variable environments, humans regulate their behavior by modulating gains in sensory-to-motor processing. In this study, we measured a simple eye movement, the ocular following response (OFR), in monkeys to study the neuronal basis of adaptive motor learning in the visuomotor processing stream. The medial superior temporal (MST) area of the cerebral cortex is a critical site for contextual gain modulation of the OFR. However, the role of MST neurons in adaptive gain modulation of the OFR remains unknown...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28101963/extreme-biophysics-enzymes-under-pressure
#6
Qi Huang, Jocelyn M Rodgers, Russell J Hemley, Toshiko Ichiye
A critical question about piezophilic (pressure-loving) microbes is how their constituent molecules maintain function under high pressure. Here, factors are examined that may lead to the increased activity under pressure in dihydrofolate reductase from the piezophilic Moritella profunda compared to the homologous enzyme from the mesophilic Escherichia coli. Molecular dynamics simulations are performed at various temperatures and pressures to examine how pressure affects the flexibility of the enzymes from these two microbes, since both stability and flexibility are necessary for enzyme activity...
January 19, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28097277/combining-the-spin-separated-exact-two-component-relativistic-hamiltonian-with-the-equation-of-motion-coupled-cluster-method-for-the-treatment-of-spin-orbit-splittings-of-light-and-heavy-elements
#7
Zhanli Cao, Zhendong Li, Fan Wang, Wenjian Liu
The spin-separated exact two-component (X2C) relativistic Hamiltonian [sf-X2C+so-DKHn, J. Chem. Phys., 2012, 137, 154114] is combined with the equation-of-motion coupled-cluster method with singles and doubles (EOM-CCSD) for the treatment of spin-orbit splittings of open-shell molecular systems. Scalar relativistic effects are treated to infinite order from the outset via the spin-free part of the X2C Hamiltonian (sf-X2C), whereas the spin-orbit couplings (SOC) are handled at the CC level via the first-order Douglas-Kroll-Hess (DKH) type of spin-orbit operator (so-DKH1)...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28095134/physical-and-occupational-therapy-for-a-teenager-with-acute-flaccid-myelitis-a-case-report
#8
Tracy Kornafel, Elaine Y Tsao, Emily Sabelhaus, Lori Surges, Susan D Apkon
AIMS: The purpose of this case report is to describe the inpatient rehabilitation program of a 13-year-old boy with acute flaccid myelitis (AFM), specific to physical and occupational therapy examination, treatment, and outcomes. CASE DESCRIPTION: AFM is a rare, acute neurologic illness in children and young adults who present with weakness and/or paralysis of unknown etiology. The teenager was admitted to the program, dependent for all mobility and self-care. Interventions focused on range of motion, transfer training, self-care, power wheelchair mobility, and environmental adaptations...
January 17, 2017: Physical & Occupational Therapy in Pediatrics
https://www.readbyqxmd.com/read/28087062/timing-and-magnitude-of-lumbar-spine-contribution-to-trunk-forward-bending-and-backward-return-in-patients-with-acute-low-back-pain
#9
Iman Shojaei, Milad Vazirian, Elizabeth G Salt, Linda R Van Dillen, Babak Bazrgari
Alterations in the lumbo-pelvic coordination denote changes in neuromuscular control of trunk motion as well as load sharing between passive and active tissues in the lower back. Differences in timing and magnitude aspects of lumbo-pelvic coordination between patients with chronic low back pain (LBP) and asymptomatic individuals have been reported; yet, the literature on lumbo-pelvic coordination in patients with acute LBP is scant. A case-control study was conducted to explore the differences in timing and magnitude aspects of lumbo-pelvic coordination between females with (n=19) and without (n=19) acute LBP...
January 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28074936/hygroscopic-motions-of-fossil-conifer-cones
#10
Simon Poppinga, Nikolaus Nestle, Andrea Šandor, Bruno Reible, Tom Masselter, Bernd Bruchmann, Thomas Speck
Conifer cones represent natural, woody compliant structures which move their scales as passive responses to changes in environmental humidity. Here we report on water-driven opening and closing motions in coalified conifer cones from the Eemian Interglacial (approx. 126,000-113,000 years BP) and from the Middle Miocene (approx. 16.5 to 11.5 million years BP). These cones represent by far the oldest documented evidence of plant parts showing full functionality of such passive hydraulically actuated motion. The functional resilience of these structures is far beyond the biological purpose of seed dispersal and protection and is because of a low level of mineralization of the fossils...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28065851/high-resolution-distortion-free-diffusion-imaging-using-hybrid-spin-warp-and-echo-planar-psf-encoding-approach
#11
Myung-Ho In, Oleg Posnansky, Oliver Speck
High-resolution diffusion-weighted imaging (DWI) has great potential to provide unique information about tissue microstructure in-vivo. Although single-shot echo-planar imaging (EPI) is a most popular tool for DWI, its application for high-resolution DWI is limited due to T2* blurring and susceptibility- and eddy-current-induced geometric distortions, especially at ultra-high field (UHF) such as 7T. In this study, we adapt a hybrid spin-warp and echo-planar encoding strategy inspired by point spread function (PSF) mapping and optimize it for high-resolution and distortion-free diffusion imaging applications...
January 5, 2017: NeuroImage
https://www.readbyqxmd.com/read/28065606/neurons-responsive-to-global-visual-motion-have-unique-tuning-properties-in-hummingbirds
#12
Andrea H Gaede, Benjamin Goller, Jessica P M Lam, Douglas R Wylie, Douglas L Altshuler
Neurons in animal visual systems that respond to global optic flow exhibit selectivity for motion direction and/or velocity. The avian lentiformis mesencephali (LM), known in mammals as the nucleus of the optic tract (NOT), is a key nucleus for global motion processing [1-4]. In all animals tested, it has been found that the majority of LM and NOT neurons are tuned to temporo-nasal (back-to-front) motion [4-11]. Moreover, the monocular gain of the optokinetic response is higher in this direction, compared to naso-temporal (front-to-back) motion [12, 13]...
December 29, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/28059774/long-time-atomistic-dynamics-through-a-new-self-adaptive-accelerated-molecular-dynamics-method
#13
Ning Gao, Li Yang, Fei Gao, Richard Kurtz, Damien West, Shengbai Zhang
A self-adaptive accelerated molecular dynamics method is developed to model the infrequent atomic-scale events, especially for treating events that occur on a rugged free-energy surface. Key in the new development is the use of the total displacement of the system at a given temperature to construct a boost-potential, which is slowly increased to accelerate the dynamics. By allowing the system to evolve from one steady-state configuration to another by overcoming the transition state, this self-evolving approach makes it possible to explore the coupled motion of species that migrate on vastly different time scales...
January 6, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28057581/individual-differences-in-motion-induced-blindness-the-effects-of-mask-coherence-and-depth-ordering
#14
John E Sparrow, Joseph A LaBarre, Brianna Sargent Merrill
Motion-induced blindness (MIB; Bonneh, Cooperman, & Sagi, 2001) is a visual phenomenon in which salient, stationary high-contrast targets are perceived to disappear and reappear when viewed within a moving background mask. The present study examined the effects of depth ordering (three levels) and mask motion coherence (0%, 50%, and 100% coherence of the mask elements), as well as the interaction effects between these two variables, especially taking note of between-subject variation. It is clear that individuals experience different amounts of MIB, indexed using average, cumulative, and normalized measures...
January 2, 2017: Vision Research
https://www.readbyqxmd.com/read/28055986/robust-heart-rate-estimation-using-wrist-type-photoplethysmographic-signals-during-physical-exercise-an-approach-based-on-adaptive-filtering
#15
Sibylle Fallet, Jean-Marc Vesin
Photoplethysmographic (PPG) signals are easily corrupted by motion artifacts when the subjects perform physical exercise. This paper introduces a two-step processing scheme to estimate heart rate (HR) from wrist-type PPG signals strongly corrupted by motion artifacts. Adaptive noise cancellation, using normalized least-mean-square algorithm, is first performed to attenuate motion artifacts and reconstruct multiple PPG waveforms from different combinations of corrupted PPG waveforms and accelerometer data. An adaptive band-pass filter is then used to track the common instantaneous frequency component (i...
January 5, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28048828/su-g-bra-09-estimation-of-motion-tracking-uncertainty-for-real-time-adaptive-imaging
#16
H Yan, Z Chen, R Nath, W Liu
PURPOSE: kV fluoroscopic imaging combined with MV treatment beam imaging has been investigated for intrafractional motion monitoring and correction. It is, however, subject to additional kV imaging dose to normal tissue. To balance tracking accuracy and imaging dose, we previously proposed an adaptive imaging strategy to dynamically decide future imaging type and moments based on motion tracking uncertainty. kV imaging may be used continuously for maximal accuracy or only when the position uncertainty (probability of out of threshold) is high if a preset imaging dose limit is considered...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048824/su-f-t-123-the-simulated-effect-of-the-breath-hold-reproducibility-treating-locally-advanced-lung-cancer-with-pencil-beam-scanned-proton-therapy
#17
J Dueck, R Perrin, G F Persson, A Lomax, M Josipovic, S A Engelholm, D C Weber, P Munck, A F Rosenschöld
PURPOSE: The breath-hold (BH) technique has been suggested to mitigate motion and reduce target coverage degradation due to motion effects. The aim of this study was to investigate the effect of inter-BH residual motion on the dose distribution for pencil beam scanned (PBS) proton therapy of locally-advanced lung cancer patients. METHODS: A dataset of visually-guided BH CT scans was acquired (10 scans per patient) taken from five lung cancer patients: three intra-fractionally repeated CT scans on treatment days 2,16 and 31, in addition to the day 0 planning CT scan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048766/su-g-bra-16-target-dose-comparison-for-dynamic-mlc-tracking-and-mid-ventilation-planning-in-lung-radiotherapy-subject-to-intrafractional-baseline-drifts
#18
M J Menten, M F Fast, S Nill, U Oelfke
PURPOSE: Lung tumor motion during radiotherapy can be accounted for by expanded treatment margins, for example using a mid-ventilation planning approach, or by localizing the tumor in real-time and adapting the treatment beam with multileaf collimator (MLC) tracking. This study evaluates the effect of intrafractional changes in the average tumor position (baseline drifts) on these two treatment techniques. METHODS: Lung stereotactic treatment plans (9-beam IMRT, 54Gy/3 fractions, mean treatment time: 9...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048720/tu-ab-202-05-gpu-based-4d-deformable-image-registration-using-adaptive-tetrahedral-mesh-modeling
#19
Z Zhong, L Zhuang, X Gu, J Wang, H Chen, X Zhen
PURPOSE: Deformable image registration (DIR) has been employed today as an automated and effective segmentation method to transfer tumor or organ contours from the planning image to daily images, instead of manual segmentation. However, the computational time and accuracy of current DIR approaches are still insufficient for online adaptive radiation therapy (ART), which requires real-time and high-quality image segmentation, especially in a large datasets of 4D-CT images. The objective of this work is to propose a new DIR algorithm, with fast computational speed and high accuracy, by using adaptive feature-based tetrahedral meshing and GPU-based parallelization...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048614/su-f-t-273-using-a-diode-array-to-explore-the-weakness-of-tps-dosecalculation-algorithm-for-vmat-and-sliding-window-techniques
#20
J Park, B Lu, G Yan, J Park, F Li, J Li, C Liu
PURPOSE: To identify the weakness of dose calculation algorithm in a treatment planning system for volumetric modulated arc therapy (VMAT) and sliding window (SW) techniques using a two-dimensional diode array. METHODS: The VMAT quality assurance(QA) was implemented with a diode array using multiple partial arcs that divided from a VMAT plan; each partial arc has the same segments and the original monitor units. Arc angles were less than ± 30°. Multiple arcs delivered through consecutive and repetitive gantry operating clockwise and counterclockwise...
June 2016: Medical Physics
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