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pulse transmit time

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
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
Julio Isla, Frederic Cegla
Pulse compression has been used for decades in radar, sonar, medical and industrial ultrasound. It consists in transmitting a modulated and/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...
January 30, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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
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
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
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 to 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 an FPGA with maximum transmit and receive delay errors measured to be less than ± 1...
December 30, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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
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
Gianmarco 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 multi-element scatterer...
December 12, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Amira Ibrahim Zaki, Ehab F Badran, Said E El-Khamy
In this paper two novel space-time coding multi-input single-output (STC MISO) schemes, designed especially for Ultra-Wideband (UWB) systems, are introduced. The proposed schemes are referred to as wavelet space-time coding (WSTC) schemes. The WSTC schemes are based on two types of multiplexing, spatial and wavelet domain multiplexing. In WSTC schemes, four symbols are transmitted on the same UWB transmission pulse with the same bandwidth, symbol duration, and number of transmitting antennas of the conventional STC MISO scheme...
2016: PloS One
Vyacheslav A Trofimov, Svetlana A Varentsova
We discuss an effective method for detecting and identifying drugs using a high-noise terahertz (THz) signal. We add a noisy THz signal obtained in real conditions to the THz signal transmitted through a sample with the illicit drug methamphetamine. The insufficiency of the standard THz time-domain spectroscopy method is demonstrated, showing that this method detects the spectral features of neutral substances and explosives in a noisy THz signal. The method discussed is based upon time-dependent integral correlation criteria calculated using spectral dynamics of the medium response...
November 20, 2016: Applied Optics
S Chusri, V Chongsuvivatwong, J I Rivera, K Silpapojakul, K Singkhamanan, E McNeil, Y Doi
BACKGROUND: Acinetobacter baumannii is a major hospital-acquired pathogen in Thailand that has a negative effect on patient survival. The nature of its transmission is poorly understood. AIM: To investigate the genotypic and spatiotemporal pattern of A. baumannii infection at a hospital in Thailand. METHODS: The medical records of patients infected with A. baumannii at an 800-bed tertiary care hospital in southern Thailand between January 2010 and December 2011 were reviewed retrospectively...
January 2017: Journal of Hospital Infection
Martin Pekař, Wendy U Dittmer, Nenad Mihajlović, Gijs van Soest, Nico de Jong
The information in an ultrasound image depends on the frequency that is used. In a clinical examination it may therefore be beneficial to generate ultrasound images acquired at multiple frequencies, which is difficult to achieve with conventional transducers. Capacitive micromachined ultrasonic transducers (CMUTs) offer a frequency response that is tunable by the bias voltage. In this study we investigate this frequency tunability for ultrasonic imaging. We characterized a CMUT array operated at bias voltages up to three times higher than the collapse-voltage...
February 2017: Ultrasonics
Desmond H Y Tse, Christopher J Wiggins, Benedikt A Poser
PURPOSE: In order to fully benefit from the improved signal-to-noise and contrast-to-noise ratios at 9.4T, the challenges of B1+ inhomogeneity and the long acquisition time of high-resolution 2D gradient-recalled echo (GRE) imaging were addressed. THEORY AND METHODS: Flip angle homogenized excitations were achieved by parallel transmission (pTx) of 3-spoke pulses, designed by magnitude least-squares optimization in a slice-by-slice fashion; the acquisition time reduction was achieved by simultaneous multislice (SMS) pulses...
October 23, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Jaemyung Lim, Coskun Tekes, F Levent Degertekin, Maysam Ghovanloo
Having intravascular ultrasound (IVUS) imaging capability on guide wires used in cardiovascular interventions may eliminate the need for separate IVUS catheters and expand the use of IVUS in a larger portion of the vasculature. High frequency capacitive micro machined ultrasonic transducer (CMUT) arrays should be integrated with interface electronics and placed on the guide wire for this purpose. Besides small size, this system-on-a-chip (SoC) front-end should connect to the back-end imaging system with a minimum number of wires to preserve the critical mechanical properties of the guide wire...
September 20, 2016: IEEE Transactions on Biomedical Circuits and Systems
H F Martins, K Shi, B C Thomsen, S Martin-Lopez, M Gonzalez-Herraez, S J Savory
A major cause of faults in optical communication links is related to unintentional third party intrusions (normally related to civil/agricultural works) causing fiber breaks or cable damage. These intrusions could be anticipated and avoided by monitoring the dynamic strain recorded along the cable. In this work, a novel technique is proposed to implement real-time distributed strain sensing in parallel with an operating optical communication channel. The technique relies on monitoring the Rayleigh backscattered light from optical communication data transmitted using standard modulation formats...
September 19, 2016: Optics Express
William T Clarke, Matthew D Robson, Stefan Neubauer, Christopher T Rodgers
PURPOSE: We present a new Bloch-Siegert four Angle Saturation Transfer (BOAST) method for measuring the creatine kinase (CK) first-order effective rate constant kf in human myocardium at 7 tesla (T). BOAST combines a variant of the four-angle saturation transfer (FAST) method using amplitude-modulated radiofrequency pulses, phosphorus Bloch-Siegert B1+-mapping to determine the per-voxel flip angles, and nonlinear fitting to Bloch simulations for postprocessing. METHODS: Optimal flip angles and repetition time parameters were determined from Monte Carlo simulations...
August 31, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
David S Hersh, Anthony J Kim, Jeffrey A Winkles, Howard M Eisenberg, Graeme F Woodworth, Victor Frenkel
: : Transcranial focused ultrasound (FUS) can noninvasively transmit acoustic energy with a high degree of accuracy and safety to targets and regions within the brain. Technological advances, including phased-array transducers and real-time temperature monitoring with magnetic resonance thermometry, have created new opportunities for FUS research and clinical translation. Neuro-oncology, in particular, has become a major area of interest because FUS offers a multifaceted approach to the treatment of brain tumors...
November 2016: Neurosurgery
Wen Xiong, Philipp Ambichl, Yaron Bromberg, Brandon Redding, Stefan Rotter, Hui Cao
We experimentally generate and characterize eigenstates of the Wigner-Smith time-delay matrix, called principal modes, in a multimode fiber with strong mode coupling. The unique spectral and temporal properties of principal modes enable global control of temporal dynamics of optical pulses transmitted through the fiber, despite random mode mixing. Our analysis reveals that well-defined delay times of the eigenstates are formed by multipath interference, which can be effectively manipulated by spatial degrees of freedom of input wave fronts...
July 29, 2016: Physical Review Letters
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