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https://www.readbyqxmd.com/read/28066547/holographic-direct-pulsed-laser-writing-of-two-dimensional-nanostructures
#1
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
#2
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
https://www.readbyqxmd.com/read/28045041/relaxation-oscillations-and-hierarchy-of-feedbacks-in-mapk-signaling
#3
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
#4
Iason Zacharias Apostolakis, Matthew McGarry, Ethan Bunting, Elisa 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 <i>in vivo</i>. 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...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27992333/continuous-subresolution-displacements-in-finite-difference-simulations-of-ultrasound-propagation-and-imaging
#5
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
https://www.readbyqxmd.com/read/27959939/two-novel-space-time-coding-techniques-designed-for-uwb-miso-systems-based-on-wavelet-transform
#6
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
https://www.readbyqxmd.com/read/27869867/detection-and-identification-of-drugs-under-real-conditions-by-using-noisy-terahertz-broadband-pulse
#7
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
https://www.readbyqxmd.com/read/27865634/molecular-epidemiology-and-spatiotemporal-analysis-of-hospital-acquired-acinetobacter-baumannii-infection-in-a-tertiary-care-hospital-in-southern-thailand
#8
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
https://www.readbyqxmd.com/read/27780034/frequency-tuning-of-collapse-mode-capacitive-micromachined-ultrasonic-transducer
#9
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
https://www.readbyqxmd.com/read/27774641/high-resolution-gradient-recalled-echo-imaging-at-9-4t-using-16-channel-parallel-transmit-simultaneous-multislice-spokes-excitations-with-slice-by-slice-flip-angle-homogenization
#10
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
https://www.readbyqxmd.com/read/27662686/towards-a-reduced-wire-interface-for-cmut-based-intravascular-ultrasound-imaging-systems
#11
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
https://www.readbyqxmd.com/read/27661964/real-time-dynamic-strain-monitoring-of-optical-links-using-the-backreflection-of-live-psk-data
#12
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
https://www.readbyqxmd.com/read/27579566/creatine-kinase-rate-constant-in-the-human-heart-measured-with-3d-localization-at-7-tesla
#13
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
https://www.readbyqxmd.com/read/27552589/emerging-applications-of-therapeutic-ultrasound-in-neuro-oncology-moving-beyond-tumor-ablation
#14
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
https://www.readbyqxmd.com/read/27517771/spatiotemporal-control-of-light-transmission-through-a-multimode-fiber-with-strong-mode-coupling
#15
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
https://www.readbyqxmd.com/read/27455525/spread-spectrum-beamforming-and-clutter-filtering-for-plane-wave-color-doppler-imaging
#16
Omar Mansour, Tamie L Poepping, James C Lacefield
Plane-wave imaging is desirable for its ability to achieve high frame rates, allowing the capture of fast dynamic events and continuous Doppler data. In most implementations of plane-wave imaging, multiple low-resolution images from different plane wave tilt angles are compounded to form a single high-resolution image, thereby reducing the frame rate. Compounding improves the lateral beam profile in the high-resolution image, but it also acts as a low-pass filter in slow time that causes attenuation and aliasing of signals with high Doppler shifts...
July 21, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27455028/comparison-of-pulsed-three-dimensional-cest-acquisition-schemes-at-7-tesla-steady-state-versus-pseudosteady-state
#17
Vitaliy Khlebnikov, Nicolas Geades, Dennis W J Klomp, Hans Hoogduin, Penny Gowland, Olivier Mougin
PURPOSE: To compare two pulsed, volumetric chemical exchange saturation transfer (CEST) acquisition schemes: steady state (SS) and pseudosteady state (PS) for the same brain coverage, spatial/spectral resolution and scan time. METHODS: Both schemes were optimized for maximum sensitivity to amide proton transfer (APT) and nuclear Overhauser enhancement (NOE) effects through Bloch-McConnell simulations, and compared in terms of sensitivity to APT and NOE effects, and to transmit field inhomogeneity...
July 25, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27450152/mating-behavior-of-psammotettix-alienus-hemiptera-cicadellidae
#18
Maja Derlink, Isabelle Abt, Romain Mabon, Charlotte Julian, Meta Virant-Doberlet, Emmanuel Jacquot
The Wheat dwarf virus, the causal agent of the wheat dwarf disease, is transmitted by leafhoppers from the genus Psammotettix and currently the main protection strategy is based on the use of insecticide treatments. Sustainable management strategies for insect vectors should include methods that are targeted to disrupt reproductive behavior and here we investigated the mating behavior of Psammotettix alineus (Dahlbom 1850) in order to determine the role of vibrational signals in intra-specific communication and pair formation...
July 23, 2016: Insect Science
https://www.readbyqxmd.com/read/27423707/non-hospital-environment-contamination-with-staphylococcus-aureus-and-methicillin-resistant-staphylococcus-aureus-proportion-meta-analysis-and-features-of-antibiotic-resistance-and-molecular-genetics
#19
REVIEW
Jialing Lin, Dongxin Lin, Ping Xu, Ting Zhang, Qianting Ou, Chan Bai, Zhenjiang Yao
BACKGROUND: Staphylococcus aureus (S. aureus), including methicillin-resistant Staphylococcus aureus (MRSA), survives in dry conditions and can persist for long periods on surfaces touched by humans. Studies that estimate the proportions and characteristics of S. aureus and MRSA contamination in non-hospital environments are lacking. Therefore, we conducted a proportion meta-analysis and reviewed the features of antibiotic resistance and molecular genetics. METHODS: Articles published between January 2005 and December 2015 that studied proportions of S...
October 2016: Environmental Research
https://www.readbyqxmd.com/read/27391722/spatiotemporal-coherent-control-of-light-through-a-multiple-scattering-medium-with-the-multispectral-transmission-matrix
#20
Mickael Mounaix, Daria Andreoli, Hugo Defienne, Giorgio Volpe, Ori Katz, Samuel Grésillon, Sylvain Gigan
We report the broadband characterization of the propagation of light through a multiple scattering medium by means of its multispectral transmission matrix. Using a single spatial light modulator, our approach enables the full control of both the spatial and spectral properties of an ultrashort pulse transmitted through the medium. We demonstrate spatiotemporal focusing of the pulse at any arbitrary position and time with any desired spectral shape. Our approach opens new perspectives for fundamental studies of light-matter interaction in disordered media, and has potential applications in sensing, coherent control, and imaging...
June 24, 2016: Physical Review Letters
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