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https://www.readbyqxmd.com/read/27913924/shear-wave-elastography-reveals-different-degrees-of-passive-and-active-stiffness-of-the-neck-extensor-muscles
#1
Angela V Dieterich, Ricardo J Andrade, Guillaume Le Sant, Deborah Falla, Frank Petzke, François Hug, Antoine Nordez
PURPOSE: The neck extensor muscles contribute to spinal support and posture while performing head and neck motion. Muscle stiffness relates to passive elasticity (support) and active tensioning (posture and movement) of muscle. It was hypothesized that support and motion requirements are reflected in the distribution of stiffness between superficial and deep neck extensor muscles. METHODS: In ten healthy participants, shear modulus (stiffness) of five neck extensor muscles was determined in prone at rest and during isometric head lift at three intensities using shear wave elastography...
December 2, 2016: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/27912171/the-topographical-distribution-of-epileptic-spikes-in-juvenile-myoclonic-epilepsy-with-and-without-photosensitivity
#2
P R Bauer, K Gorgels, W Spetgens, N E C van Klink, F S S Leijten, J W Sander, G H Visser, M Zijlmans
OBJECTIVE: Up to 30% of people with juvenile myoclonic epilepsy (JME) have photoparoxysmal responses (PPR). Recent studies report on structural and pathophysiological differences between people with JME with (JME+PPR) and without PPR (JME-PPR). We investigated whether electrophysiological features outside photic stimulation differ between these subtypes. METHODS: We analysed EEG recordings of people with JME at a tertiary epilepsy centre and an academic hospital...
November 14, 2016: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/27911552/relativistic-electrons-produced-by-foreshock-disturbances-observed-upstream-of-earth-s-bow-shock
#3
L B Wilson, D G Sibeck, D L Turner, A Osmane, D Caprioli, V Angelopoulos
Charged particles can be reflected and accelerated by strong (i.e., high Mach number) astrophysical collisionless shock waves, streaming away to form a foreshock region in communication with the shock. Foreshocks are primarily populated by suprathermal ions that can generate foreshock disturbances-large-scale (i.e., tens to thousands of thermal ion Larmor radii), transient (∼5-10  per day) structures. They have recently been found to accelerate ions to energies of several keV. Although electrons in Saturn's high Mach number (M>40) bow shock can be accelerated to relativistic energies (nearly 1000 keV), it has hitherto been thought impossible to accelerate electrons beyond a few tens of keV at Earth's low Mach number (1≤M<20) bow shock...
November 18, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27910956/spin-crossover-materials-towards-microwave-radiation-switches
#4
Olesia I Kucheriv, Viktor V Oliynyk, Volodymyr V Zagorodnii, Vilen L Launets, Il'ya A Gural'skiy
Microwave electromagnetic radiation that ranges from one meter to one millimetre wavelengths is finding numerous applications for wireless communication, navigation and detection, which makes materials able to tune microwave radiation getting widespread interest. Here we offer a new way to tune GHz frequency radiation by using spin-crossover complexes that are known to change their various physical properties under the influence of diverse external stimuli. As a result of electronic re-configuration process, microwave absorption properties differ for high spin and low spin forms of the complex...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27910650/full-wave-feasibility-study-of-anti-radar-diagnostic-of-magnetic-field-based-on-o-x-mode-conversion-and-oblique-reflectometry-imaging
#5
Orso Meneghini, Francesco A Volpe
An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contains information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910506/assessment-of-the-measurement-performance-of-the-in-vessel-system-of-gap-6-of-the-iter-plasma-position-reflectometer-using-a-finite-difference-time-domain-maxwell-full-wave-code
#6
F da Silva, S Heuraux, E Ricardo, P Quental, J Ferreira
We conducted a first assessment of the measurement performance of the in-vessel components at gap 6 of the ITER plasma position reflectometry with the aid of a synthetic Ordinary Mode (O-mode) broadband frequency-modulated continuous-wave reflectometer implemented with REFMUL, a 2D finite-difference time-domain full-wave Maxwell code. These simulations take into account the system location within the vacuum vessel as well as its access to the plasma. The plasma case considered is a baseline scenario from Fusion for Energy...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910493/plasma-characterization-using-ultraviolet-thomson-scattering-from-ion-acoustic-and-electron-plasma-waves-invited
#7
R K Follett, J A Delettrez, D H Edgell, R J Henchen, J Katz, J F Myatt, D H Froula
Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 10(21) cm(-3), which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910349/multi-channel-poloidal-correlation-reflectometry-on-experimental-advanced-superconducting-tokamak
#8
H Qu, T Zhang, X Han, H M Xiang, F Wen, K N Geng, Y M Wang, D F Kong, J Q Cai, C B Huang, Y Gao, X Gao, S Zhang
A new multi-channel poloidal correlation reflectometry is developed at Experimental Advanced Superconducting Tokamak. Eight dielectric resonator oscillators with frequencies of 12.5 GHz, 13.5 GHz, 14.5 GHz, 15 GHz, 15.5 GHz, 16 GHz, 17 GHz, and 18 GHz are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together. The output waves are launched by one single antenna after passing through a 20 dB directional coupler which can provide the reference signal...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27908086/identification-of-the-rayleigh-surface-waves-for-estimation-of-viscoelasticity-using-the-surface-wave-elastography-technique
#9
Xiaoming Zhang
The purpose of this Letter to the Editor is to demonstrate an effective method for estimating viscoelasticity based on measurements of the Rayleigh surface wave speed. It is important to identify the surface wave mode for measuring surface wave speed. A concept of start frequency of surface waves is proposed. The surface wave speeds above the start frequency should be used to estimate the viscoelasticity of tissue. The motivation was to develop a noninvasive surface wave elastography (SWE) technique for assessing skin disease by measuring skin viscoelastic properties...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27908078/kirchhoff-approximation-for-backscattering-from-a-partially-exposed-rigid-sphere-at-a-flat-interface
#10
Aaron M Gunderson, Philip L Marston
The Kirchhoff approximation (KA) is used to model backscatter of sound from a partially exposed, rigid sphere at a flat free interface of two homogenous media. Scattered wavefields are calculated through numerical integration on the sphere of the Kirchhoff integral, requiring detailed knowledge of the illuminated region for each scattering path. This approach avoids amplitude discontinuities resulting from geometric transitions in the number of reflected rays. Reflections from the interface are modeled through use of an image source, positioned symmetrically relative to the real source...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27908056/reconstruction-of-piano-hammer-force-from-string-velocity
#11
Antoine Chaigne
A method is presented for reconstructing piano hammer forces through appropriate filtering of the measured string velocity. The filter design is based on the analysis of the pulses generated by the hammer blow and propagating along the string. In the five lowest octaves, the hammer force is reconstructed by considering two waves only: the incoming wave from the hammer and its first reflection at the front end. For the higher notes, four- or eight-wave schemes must be considered. The theory is validated on simulated string velocities by comparing imposed and reconstructed forces...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27906502/using-our-hands-to-change-our-minds
#12
REVIEW
Susan Goldin-Meadow
Jean Piaget was a master at observing the routine behaviors children produce as they go from knowing less to knowing more about at a task, and making inferences not only about how children understand the task at each point, but also about how they progress from one point to the next. This article examines a routine behavior that Piaget overlooked-the spontaneous gestures speakers produce as they explain their solutions to a problem. These gestures are not mere hand waving. They reflect ideas that the speaker has about the problem, often ideas that are not found in that speaker's talk...
December 1, 2016: Wiley Interdisciplinary Reviews. Cognitive Science
https://www.readbyqxmd.com/read/27906359/monitoring-blood-vital-bio-signs-using-secondary-speckle-patterns
#13
Talia Sirkis, Yevgeny Beiderman, Sergey Agdarov, Yafim Beiderman, Zeev Zalevsky
Continuous noninvasive measurement of vital bio-signs, such as cardiopulmonary parameters, is an important tool in the evaluation process of the patient's physiological condition and in the health monitoring of the patient. On the demand of new enabling technologies, some works have been done in continuous monitoring of blood pressure and pulse wave velocity. In this paper, we introduce further application of a novel technique for remote noncontact blood pulse wave velocity and pressure measurement based on tracking the temporal changes of reflected secondary speckle patterns produced in human skin when illuminated by a laser beam...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906358/monitoring-blood-vital-bio-signs-using-secondary-speckle-patterns
#14
Talia Sirkis, Yevgeny Beiderman, Sergey Agdarov, Yafim Beiderman, Zeev Zalevsky
Continuous noninvasive measurement of vital bio-signs, such as cardiopulmonary parameters, is an important tool in the evaluation process of the patient's physiological condition and in the health monitoring of the patient. On the demand of new enabling technologies, some works have been done in continuous monitoring of blood pressure and pulse wave velocity. In this paper, we introduce further application of a novel technique for remote noncontact blood pulse wave velocity and pressure measurement based on tracking the temporal changes of reflected secondary speckle patterns produced in human skin when illuminated by a laser beam...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906353/achieving-flexible-low-scattering-metasurface-based-on-randomly-distribution-of-meta-elements
#15
Junming Zhao, Boyu Sima, Nan Jia, Cheng Wang, Bo Zhu, Tian Jiang, Yijun Feng
In the paper, a flexible low-scattering metasurface is proposed and realized. The layout is composed of similar "#" shaped elements with variable sizes which are randomly distributed along the surface. The various dimensions of the meta-elements lead to different reflection phases for the meta-elements with respect to the incident plane wave, resulting a diffuse reflection surface and exhibiting a broadband backward low-scattering property. In consideration of the flexibility, metasurfaces composed of printed metallic element films attaching with flexible substrate are designed, fabricated and measured in microwave domain...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906330/improved-sesams-for-femtosecond-pulse-generation-approaching-the-kw-average-power-regime
#16
C G E Alfieri, A Diebold, F Emaury, E Gini, C J Saraceno, U Keller
We present semiconductor saturable absorber mirrors (SESAMs) that can potentially support femtosecond pulses from ultrafast thin disk lasers (TDLs) with high average power approaching the kW-power level and high pulse energy in the range of 100 µJ to 1 mJ at megahertz pulse repetition rates. For high-power operation, the SESAM parameters will ultimately limit the shortest pulse duration from a soliton mode-locked laser before mode locking instabilities such as multiple pulsing instabilities and continuous wave (cw) breakthrough start to occur...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906247/broadband-polarizers-based-on-graphene-metasurfaces
#17
Tianjing Guo, Christos Argyropoulos
We present terahertz metasurfaces based on aligned rectangular graphene patches placed on top of a dielectric layer to convert the transmitted linearly polarized waves to circular or elliptical polarized radiation. Our results lead to the design of an ultrathin broadband terahertz quarter-wave plate. In addition, ultrathin metasurfaces based on the arrays of L-shaped graphene periodic patches are demonstrated to achieve broadband cross-polarization transformation in reflection and transmission. The proposed metasurface designs have tunable responses and are envisioned to become the building blocks of several integrated terahertz systems...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27906223/axial-super-resolution-evanescent-wave-tomography
#18
Sarang Pendharker, Swapnali Shende, Ward Newman, Stephen Ogg, Neda Nazemifard, Zubin Jacob
Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27901088/tunable-microwave-metasurfaces-for-high-performance-operations-dispersion-compensation-and-dynamical-switch
#19
He-Xiu Xu, Shiwei Tang, Shaojie Ma, Weijie Luo, Tong Cai, Shulin Sun, Qiong He, Lei Zhou
Controlling the phase distributions on metasurfaces leads to fascinating effects such as anomalous light refraction/reflection, flat-lens focusing, and optics-vortex generation. However, metasurfaces realized so far largely reply on passive resonant meta-atoms, whose intrinsic dispersions limit such passive meta-devices' performances at frequencies other than the target one. Here, based on tunable meta-atoms with varactor diodes involved, we establish a scheme to resolve these issues for microwave metasurfaces, in which the dispersive response of each meta-atom is precisely controlled by an external voltage imparted on the diode...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27901053/visual-search-performance-is-predicted-by-both-prestimulus-and-poststimulus-electrical-brain-activity
#20
Berry van den Berg, Lawrence G Appelbaum, Kait Clark, Monicque M Lorist, Marty G Woldorff
An individual's performance on cognitive and perceptual tasks varies considerably across time and circumstances. We investigated neural mechanisms underlying such performance variability using regression-based analyses to examine trial-by-trial relationships between response times (RTs) and different facets of electrical brain activity. Thirteen participants trained five days on a color-popout visual-search task, with EEG recorded on days one and five. The task was to find a color-popout target ellipse in a briefly presented array of ellipses and discriminate its orientation...
November 30, 2016: Scientific Reports
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