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https://www.readbyqxmd.com/read/28420761/in-situ-measurements-of-tensile-forces-in-the-tibialis-anterior-tendon-of-the-rat-in-concentric-isometric-and-resisted-co-contractions
#1
Martin Schmoll, Ewald Unger, Hazel Sutherland, Michael Haller, Manfred Bijak, Hermann Lanmüller, Jonathan C Jarvis
Tensile-force transmitted by the tibialis anterior (TA) tendon of 11 anesthetized adult male Wistar rats (body-mass: 360.6 ± 66.3 g) was measured in-situ within the intact biomechanical system of the hind-limb using a novel miniature in-line load-cell. The aim was to demonstrate the dependence of the loading-profile experienced by the muscle, on stimulation-frequency and the resistance to shortening in a group of control-animals. Data from these acute-experiments shows the type of loading achievable by means of implantable electrical stimulators activating agonists or agonist/antagonist groups of muscles during programmed resistance-training in freely moving healthy subjects...
April 2017: Physiological Reports
https://www.readbyqxmd.com/read/28418076/ultrasonic-modulation-of-tissue-optical-properties-in-ex-vivo-porcine-skin-to-improve-transmitted-transdermal-laser-intensity
#2
Paul J D Whiteside, Chenxi Qian, Nicholas Golda, Heather K Hunt
BACKGROUND AND OBJECTIVE: Applications of light-based energy devices involving optical targets within the dermis frequently experience negative side-effects resultant from surface scattering and excess optical absorption by epidermal melanin. As a broadband optical absorber, melanin decreases the efficacy of light-based treatments throughout the ultraviolet, visible, and near-infrared spectra while also generating additional heat within the surface tissue that can lead to inflammation or tissue damage...
April 18, 2017: Lasers in Surgery and Medicine
https://www.readbyqxmd.com/read/28394085/dual-echo-epi-sequence-for-integrated-distortion-correction-in-3d-time-resolved-hyperpolarized-13-c-mri
#3
Benjamin J Geraghty, Justin Y C Lau, Albert P Chen, Charles H Cunningham
PURPOSE: To provide built-in off-resonance correction in time-resolved, volumetric hyperpolarized (13) C metabolic imaging by implementing a novel dual-echo 3D echo-planar imaging (EPI) sequence and reconstruction. METHODS: A spectral-spatial pulse for single-resonance excitation followed by a dual-echo 3D EPI readout was implemented to provide 64 × 8 × 6 cm(3) coverage at 5 × 5 × 5 mm(3) nominal resolution. Multiple sources of EPI distortions were encoded using a multi-echo (1) H EPI reference scan...
April 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28381021/handheld-free-space-quantum-key-distribution-with-dynamic-motion-compensation
#4
Hyunchae Chun, Iris Choi, Grahame Faulkner, Larry Clarke, Bryan Barber, Glenn George, Colin Capon, Antti Niskanen, Joachim Wabnig, Dominic O'Brien, David Bitauld
Mobile devices have become an inseparable part of our everyday life. They are used to transmit an ever-increasing amount of sensitive health, financial and personal information. This exposes us to the growing scale and sophistication of cyber-attacks. Quantum Key Distribution (QKD) can provide unconditional and future-proof data security but implementing it for handheld mobile devices comes with specific challenges. To establish security, secret keys of sufficient length need to be transmitted during the time of a handheld transaction (~1s) despite device misalignment, ambient light and user's inevitable hand movements...
March 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28372047/detection-of-forward-scattering-from-an-intruder-in-a-dynamic-littoral-environment
#5
Bo Lei, Yixin Yang, Kunde Yang, Yuanliang Ma
Forward scattering always occurs when an intruder moves into an underwater area between a source and a receiver. The detection of this forward-scattered signal is a challenge because a strong direct blast overwhelms the forward-scattered signal. Accordingly, an adaptive scheme for detecting the forward scattering introduced by an intruder in dynamic shallow water is proposed in this study. A short pulse was transmitted repeatedly in the water. The recorded direct blast and forward-scattered signal were assumed to be weakly correlated...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28370494/tailored-spiral-in-out-spectral-spatial-water-suppression-pulses-for-magnetic-resonance-spectroscopic-imaging
#6
Jun Ma, Carrie Wismans, Zhipeng Cao, Dennis W J Klomp, Jannie P Wijnen, William A Grissom
PURPOSE: To develop short water suppression sequences for 7 T magnetic resonance spectroscopic imaging, with mitigation of subject-specific transmit RF field ( B1+) inhomogeneity. METHODS: Patient-tailored spiral in-out spectral-spatial saturation pulses were designed for a three-pulse WET water suppression sequence. The pulses' identical spatial subpulses were designed using patient-specific B1+ maps and a spiral in-out excitation k-space trajectory. The subpulse train was weighted by a spectral envelope that was root-flipped to minimize peak RF demand...
March 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28368803/a-delayed-excitation-data-acquisition-method-for-high-frequency-ultrasound-imaging
#7
Weibao Qiu, Jingjing Xia, Yulong Shi, Peitian Mu, Xingying Wang, Mengdi Gao, Congzhi Wang, Yang Xiao, Ge Yang, Jihong Liu, Lei Sun, Hairong Zheng
High-frequency ultrasound imaging (at >20 MHz) has gained widespread attention due to its high spatial resolution being useful for basic cardiovascular and cancer research involving small animals. The sampling rate of the analog-to-digital converter in a high-frequency ultrasound system usually needs to be higher than 120 MHz in order to satisfy the Nyquist sampling-rate requirement. However, the sampling rate is typically within the range of 40-60 MHz in a traditional ultrasound system, and so we propose a delayed-excitation method for performing high-frequency ultrasound imaging with a traditional data acquisition scheme...
March 28, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28336426/sar-simulations-safety
#8
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
At ultra-high fields, the assessment of radiofrequency (RF) safety presents several new challenges compared to low-field systems. Multi-channel RF transmit coils in combination with parallel transmit techniques produce time-dependent and spatially varying power loss densities in the tissue. Further, in ultra-high-field systems, localized field effects can be more pronounced due to a transition from the quasistationary to the electromagnetic field regime. Consequently, local information on the RF field is required for reliable RF safety assessment as well as for monitoring of RF exposure during MR examinations...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28269349/an-inductive-narrow-pulse-rfid-telemetry-system-for-gastric-slow-waves-monitoring
#9
Amir Javan-Khoskholgh, Zaid Abukhalaf, Ji Li, Larry S Miller, Mehdi Kiani, Aydin Farajidavar
We present a passive data telemetry system for real-time monitoring of gastric electrical activity of a living subject. The system is composed of three subsystems: an implantable unit (IU), a wearable unit (WU), and a stationary unit (SU). Data communication between the IU and WU is based on a radio-frequency identification (RFID) link operating at 13.56 MHz. Since wireless power transmission and reverse data telemetry system share the same inductive interface, a load shift keying (LSK)-based differential pulse position (DPP) coding data communication with only 6...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28241577/gouy-phase-shift-for-annular-beam-profiles-in-attosecond-experiments
#10
F Schlaepfer, A Ludwig, M Lucchini, L Kasmi, M Volkov, L Gallmann, U Keller
Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-harmonic generation (HHG). Furthermore, the strong absorption of materials at the extreme ultraviolet (XUV) wavelengths of the attosecond pulses typically prevents the use of transmissive optics. As a result, pump and probe beams are typically recombined geometrically with a center-hole mirror that reflects the larger IR beam and transmits the smaller XUV, which leads to an annular beam profile of the IR...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28227591/an-inductive-narrow-pulse-rfid-telemetry-system-for-gastric-slow-waves-monitoring
#11
Amir Javan-Khoskholgh, Zaid Abukhalaf, Ji Li, Larry S Miller, Mehdi Kiani, Aydin Farajidavar, Amir Javan-Khoskholgh, Zaid Abukhalaf, Ji Li, Larry S Miller, Mehdi Kiani, Aydin Farajidavar, Larry S Miller, Amir Javan-Khoskholgh, Ji Li, Mehdi Kiani, Zaid Abukhalaf
We present a passive data telemetry system for real-time monitoring of gastric electrical activity of a living subject. The system is composed of three subsystems: an implantable unit (IU), a wearable unit (WU), and a stationary unit (SU). Data communication between the IU and WU is based on a radio-frequency identification (RFID) link operating at 13.56 MHz. Since wireless power transmission and reverse data telemetry system share the same inductive interface, a load shift keying (LSK)-based differential pulse position (DPP) coding data communication with only 6...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28212092/modeling-contrast-imaging-assisted-optimal-targeted-drug-delivery-a-touchable-communication-channel-estimation-and-waveform-design-perspective
#12
Yifan Chen, Yu Zhou, Ross Murch, Panagiotis Kosmas
To maximize the effect of treatment and minimize the adverse effect on patients, we propose to optimize nanorobotsassisted targeted drug delivery (TDD) for locoregional treatment of tumor from the perspective of touchable communication channel estimation and waveform design. The drug particles are the information molecules; the loading/injection and unloading of the drug correspond to the transmitting and receiving processes; the concentration-time profile of the drug particles administered corresponds to the signalling pulse...
February 15, 2017: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28166492/coded-excitation-for-pulse-echo-systems
#13
Julio Isla, Frederic Cegla
Pulse compression has been used for decades in radar, sonar, medical, and industrial ultrasound. It consists in transmitting a modulated or coded excitation, which is then cross-correlated with the received signal such that received echoes are time compressed, thereby increasing their intensity and hence the system resolution and signal-to-noise ratio (SNR). A central problem in pulse-echo systems is that while longer coded excitations yield higher SNRs, the length of the coded excitation or sequence is limited by the distance between the closest reflector and the transmitter/receiver...
April 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28147668/nmr-measurement-system-including-two-synchronized-ring-buffers-with-128-rf-coils-for-in-situ-water-monitoring-in-a-polymer-electrolyte-fuel-cell
#14
Kuniyasu Ogawa, Tomoyuki Haishi, Masaru Aoki, Hiroshi Hasegawa, Shinichi Morisaka, Seitaro Hashimoto
A small radio-frequency (rf) coil inserted into a polymer electrolyte fuel cell (PEFC) can be used to acquire nuclear magnetic resonance (NMR) signals from the water in a membrane electrode assembly (MEA) or in oxygen gas channels in the PEFC. Measuring the spatial distribution of the water in a large PEFC requires using many rf probes, so an NMR measurement system which acquires NMR signals from 128 rf probes at intervals of 0.5 s was manufactured. The system has eight rf transceiver units with a field-programmable gate array (FPGA) for modulation of the excitation pulse and quadrature phase detection of the NMR signal, and one control unit with two ring buffers for data control...
January 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28106423/amplification-of-relativistic-electron-bunches-by-acceleration-in-laser-fields
#15
J Braenzel, A A Andreev, F Abicht, L Ehrentraut, K Platonov, M Schnürer
Direct acceleration of electrons in a coherent, intense light field is revealed by a remarkable increase of the electron number in the MeV energy range. Laser irradiation of thin polymer foils with a peak intensity of ∼1×10^{20}  W/cm^{2} releases electron bunches along the laser propagation direction that are postaccelerated in the partly transmitted laser field. They are decoupled from the laser field at high kinetic energies, when a second foil target at an appropriate distance prevents their subsequent deceleration in the declining laser field...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28066547/holographic-direct-pulsed-laser-writing-of-two-dimensional-nanostructures
#16
Bader AlQattan, Haider Butt, Aydin Sabouri, Ali K Yetisen, Rajib Ahmed, Nasim Mahmoodi
The development of accurate and rapid techniques to produce nanophotonic structures is essential in data storage, sensors, and spectroscopy. Existing bottom-up and top-down approaches to fabricate nanophotonic devices are high cost and time consuming, limiting their mass manufacturing and practical applications. Here, we demonstrate a strategy to rapidly create 25-40 nm thick 1/2D Au-Ti nanopatterns using holographic direct laser interference patterning (DLIP). Pulses of an Nd:YAG laser (1064 nm) in holographic Denisyuk reflection mode were used to create ablative interference fringes...
December 4, 2016: RSC Advances
https://www.readbyqxmd.com/read/28055864/a-sub-nyquist-variable-sampling-high-frequency-phased-array-beamformer
#17
Christopher A Samson, Andre Bezanson, Jeremy A Brown
A digital receive beamformer implementing a "one sample per pixel" variable sampling technique is described. The sampling method reduces the required sampling rates by a factor of 3, and reduces the data capture rate by a factor of 2, in comparison with the previous systems based on variable sampling. The sampling method is capable of estimating broadband pulse envelopes accurate for bandwidths up to 83.0%. This beamforming method has been implemented on a field-programmable gate array with maximum transmit and receive delay errors measured to be less than ±1...
March 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28045041/relaxation-oscillations-and-hierarchy-of-feedbacks-in-mapk-signaling
#18
Marek Kochańczyk, Paweł Kocieniewski, Emilia Kozłowska, Joanna Jaruszewicz-Błońska, Breanne Sparta, Michael Pargett, John G Albeck, William S Hlavacek, Tomasz Lipniacki
We formulated a computational model for a MAPK signaling cascade downstream of the EGF receptor to investigate how interlinked positive and negative feedback loops process EGF signals into ERK pulses of constant amplitude but dose-dependent duration and frequency. A positive feedback loop involving RAS and SOS, which leads to bistability and allows for switch-like responses to inputs, is nested within a negative feedback loop that encompasses RAS and RAF, MEK, and ERK that inhibits SOS via phosphorylation. This negative feedback, operating on a longer time scale, changes switch-like behavior into oscillations having a period of 1 hour or longer...
January 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28002039/pulse-wave-imaging-using-coherent-compounding-in-a-phantom-and-in-vivo
#19
Iason Zacharias Apostolakis, Matthew D J McGarry, Ethan A Bunting, Elisa E Konofagou
Pulse wave velocity (PWV) is a surrogate marker of arterial stiffness linked to cardiovascular morbidity. Pulse wave imaging (PWI) is a technique developed by our group for imaging the pulse wave propagation in vivo. PWI requires high temporal and spatial resolution, which conventional ultrasonic imaging is unable to simultaneously provide. Coherent compounding is known to address this tradeoff and provides full aperture images at high frame rates. This study aims to implement PWI using coherent compounding within a GPU-accelerated framework...
March 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27992333/subresolution-displacements-in-finite-difference-simulations-of-ultrasound-propagation-and-imaging
#20
Gianmarco F Pinton
Time domain finite difference simulations are used extensively to simulate wave propagation. They approximate the wave field on a discrete domain with a grid spacing that is typically on the order of a tenth of a wavelength. The smallest displacements that can be modeled by this type of simulation are thus limited to discrete values that are integer multiples of the grid spacing. This paper presents a method to represent continuous and subresolution displacements by varying the impedance of individual elements in a multielement scatterer...
March 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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