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https://www.readbyqxmd.com/read/28058731/improved-intercostal-hifu-ablation-using-a-phased-array-transducer-based-on-fermat-s-spiral-and-voronoi-tessellation-a-numerical-evaluation
#1
Pascal Ramaekers, Mario Ries, Chrit T W Moonen, Martijn de Greef
PURPOSE: A major complication for abdominal High Intensity Focused Ultrasound (HIFU) applications is the obstruction of the acoustic beam path by the thoracic cage, which absorbs and reflects the ultrasonic energy leading to undesired overheating of healthy tissues in the pre-focal area. Prior work has investigated the determination of optimized transducer apodization laws, which allow for a reduced rib exposure whilst (partially) restoring focal point intensity through power compensation...
January 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/28046575/tu-fg-209-02-effective-elimination-of-aliased-signal-using-an-apodized-aperture-pixel-design
#2
A Shankar, M Russ, S Vijayan, D Bednarek, S Rudin
PURPOSE: Signal and noise aliasing are major issues with high resolution direct and indirect detectors for which the Apodized Aperture Pixel (AAP) design provides an alternative solution. METHODS: High resolution detectors for neurovascular interventions have MTFs that remain significant even at the Nyquist frequency. Under-sampling in such detectors, leads to aliasing of object frequencies and noise. Frequencies above the Nyquist wrap into the lower frequency range leading to aliasing...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28033498/a-robust-approach-to-apodization-design-in-phased-arrays-for-ultrasound-imaging
#3
Amir Gholampour, Sayed Mahmoud Sakhaei, Seyed Mehdi Hosseini Andargoli
Apodization is a common way to control the sidelobe level of the beampattern. To design the apodization, it is usually assumed that the medium is homogenous with a fixed value of sound speed, despite the fact that the speed may vary by a great value in practical situations. On the other hand, the beamforming performance is highly affected by the speed value. In this paper, the beampattern sensitivity to the speed variations is firstly investigated through both mathematical representations and simulation results showing that the speed errors lead to a sever degradation of the beampattern in terms of both mainlobe width and sidelobe level...
December 16, 2016: Ultrasonics
https://www.readbyqxmd.com/read/28031419/serum-levels-of-apolipoproteins-and-incident-type-2-diabetes-a-prospective-cohort-study
#4
Adela Brahimaj, Symen Ligthart, M Arfan Ikram, Albert Hofman, Oscar H Franco, Eric J G Sijbrands, Maryam Kavousi, Abbas Dehghan
OBJECTIVE: We aimed to investigate the role of serum levels of various apolipoproteins on the risk for type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: We used data from 971 individuals from the prospective population-based Rotterdam Study. We studied the association of HDL cholesterol (HDL-C), apoA1, apoCIII, apoD, and apoE as well as the ratios of apolipoproteins with apoA1 with the risk of T2D. All apolipoproteins, ratios, and HDL-C levels were naturally log-transformed to reach normal distribution...
December 28, 2016: Diabetes Care
https://www.readbyqxmd.com/read/28026758/a-compressed-sensing-strategy-for-synthetic-transmit-aperture-ultrasound-imaging
#5
Jing Liu, Qiong He, Jianwen Luo
A novel beamforming technique, named compressed sensing based synthetic transmit aperture (CS-STA) is proposed to speed up the acquisition of ultrasound imaging. This technique consists of three steps. First, the ultrasound transducer transmits randomly apodized plane waves for a number of times and receives the backscattered echoes. Second, the recorded backscattered echoes are used to recover the full channel dataset of synthetic transmit aperture (STA) with a compressed sensing (CS) reconstruction algorithm...
December 23, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28009553/generation-of-apodized-x-ray-illumination-and-its-application-to-scanning-and-diffraction-microscopy
#6
Krishna P Khakurel, Takashi Kimura, Hiroki Nakamori, Takumi Goto, Satoshi Matsuyama, Tomoya Sasaki, Masashi Takei, Yoshiki Kohmura, Tetsuya Ishikawa, Kazuto Yamauchi, Yoshinori Nishino
X-ray science has greatly benefited from the progress in X-ray optics. Advances in the design and the manufacturing techniques of X-ray optics are key to the success of various microscopic and spectroscopic techniques practiced today. Here the generation of apodized X-ray illumination using a two-stage deformable Kirkpatrick-Baez mirror system is presented. Such apodized illumination is marked by the suppression of the side-lobe intensities of the focused beam. Thus generated apodized illumination was employed to improve the image quality in scanning X-ray fluorescence microscopy...
January 1, 2017: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/27958453/precise-parallel-optical-spectrum-analysis-using-the-advanced-two-phonon-light-scattering-combined-with-the-cross-disperser-technique
#7
A S Shcherbakov, A O Arellanes, V Chavushyan
We develop an advanced approach to the optical spectrometer with acousto-optical dynamic grating for the Guillermo Haro astrophysical observatory (Mexico). The progress consists of two principle novelties. First is the use of the acousto-optical nonlinearity of two-phonon light scattering in crystals with linear acoustic losses. This advanced regime of light scattering exhibits a recently revealed additional degree of freedom, which allows tuning of the frequency of elastic waves and admits the nonlinear apodization improving the dynamic range...
December 1, 2016: Applied Optics
https://www.readbyqxmd.com/read/27914989/transcriptome-analysis-of-adult-and-fetal-trabecular-meshwork-cornea-and-ciliary-body-tissues-by-rna-sequencing
#8
Megan Ulmer Carnes, R Rand Allingham, Allison Ashley-Koch, Michael A Hauser
PURPOSE: To characterize the transcriptional landscape of human adult and fetal trabecular meshwork (TM), cornea, and ciliary body (CB) tissues, and to evaluate the expression level of candidate genes selected from genetic association studies of primary-open angle glaucoma, central corneal thickness, intraocular pressure, vertical cup to disc ratio, and optic nerve parameters. METHODS: Deep RNA sequencing was performed on the selected human tissues. Transcriptome analyses were performed to 1) characterize the total number of expressed genes, 2) identify the most highly expressed genes, 3) estimate the number of novel transcripts, and 4) evaluate the expression of candidate genes in each tissue...
November 30, 2016: Experimental Eye Research
https://www.readbyqxmd.com/read/27873353/adaptively-optimized-combination-aoc-of-phased-array-mr-spectroscopy-data-in-the-presence-of-correlated-noise-compared-with-noise-decorrelated-or-whitened-methods
#9
Minjie Wu, Liang Fang, Charles E Ray, Anand Kumar, Shaolin Yang
PURPOSE: A method for adaptively optimized combination (AOC) of MR spectroscopic data from a coil array was recently introduced. The superior performance of the AOC method is evident when compared with the methods that assume uncorrelated noise between coil elements. However, it is unclear whether the AOC method represents the most optimal combination in the presence of correlated noise, when compared with the noise-decorrelated or whitened methods that specifically tackle the correlated noise between coil elements...
November 21, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27849043/optimal-2d-sim-reconstruction-by-two-filtering-steps-with-richardson-lucy-deconvolution
#10
Victor Perez, Bo-Jui Chang, Ernst Hans Karl Stelzer
Structured illumination microscopy relies on reconstruction algorithms to yield super-resolution images. Artifacts can arise in the reconstruction and affect the image quality. Current reconstruction methods involve a parametrized apodization function and a Wiener filter. Empirically tuning the parameters in these functions can minimize artifacts, but such an approach is subjective and produces volatile results. We present a robust and objective method that yields optimal results by two straightforward filtering steps with Richardson-Lucy-based deconvolutions...
November 16, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27828109/dynamics-of-accelerating-bessel-solutions-of-maxwell-s-equations
#11
Parinaz Aleahmad, Hector Moya Cessa, Ido Kaminer, Mordechai Segev, Demetrios N Christodoulides
We investigate the propagation dynamics of accelerating beams that are shape-preserving solutions of the Maxwell equations, and explore the contribution of their evanescent field components in detail. Both apodized and nonapodized Bessel beam configurations are considered. We show that, in spite of the fact that their evanescent tails do not propagate, these nonparaxial beams can still accelerate along circular trajectories and can exhibit large deflections. Subsequently, our formulation is extended in other two-dimensional vectorial arrangements...
October 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/27824570/ultrasonic-reverberation-clutter-suppression-using-multiphase-apodization-with-cross-correlation
#12
Junseob Shin, Yu Chen, Harshawn Malhi, Jesse T Yen
Despite numerous recent advances in medical ultrasound imaging, reverberation clutter from near-field anatomical structures, such as the abdominal wall, ribs, and tissue layers, is one of the major sources of ultrasound image quality degradation. Reverberation clutter signals are undesirable echoes, which arise as a result of multiple reflections of acoustic waves between the boundaries of these structures, and cause fill-in to lower image contrast. In order to mitigate the undesirable reverberation clutter effects, we present, in this paper, a new beamforming technique called multiphase apodization with cross correlation (MPAX), which is an improved version of our previous technique, dual apodization with cross correlation (DAX)...
November 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27824562/3-d-vector-flow-estimation-with-row-column-addressed-arrays
#13
Simon Holbek, Thomas Lehrmann Christiansen, Matthias Bo Stuart, Christopher Beers, Erik Vilain Thomsen, Jorgen Arendt Jensen
Simulation and experimental results from 3-D vector flow estimations for a 62 + 62 2-D row-column (RC) array with integrated apodization are presented. A method for implementing a 3-D transverse oscillation (TO) velocity estimator on a 3-MHz RC array is developed and validated. First, a parametric simulation study is conducted, where flow direction, ensemble length, number of pulse cycles, steering angles, transmit/receive apodization, and TO apodization profiles and spacing are varied, to find the optimal parameter configuration...
November 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27805685/high-efficiency-apodized-imaging-chip-fiber-grating-coupler-for-silicon-nitride-waveguides
#14
Yang Chen, Robert Halir, Íñigo Molina-Fernández, Pavel Cheben, Jian-Jun He
Chip-fiber grating couplers have been widely used in silicon-on-insulator platforms. In silicon nitride waveguides, the lower index contrast yields gratings with a weaker radiation strength and poor directionality, thereby limiting the coupling efficiency. Here we propose and design an apodized self-imaging grating coupler in silicon nitride that images an in-plane waveguide input to an output optical fiber placed at a specific distance above the chip. Both amplitude and phase apodizations are employed to engineer the transfer function of the self-imaging grating to produce an image field matching the fiber mode profile...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27805680/photonic-hilbert-transformers-based-on-laterally-apodized-integrated-waveguide-bragg-gratings-on-a-soi-wafer
#15
Hamed Pishvai Bazargani, Maurizio Burla, Lukas Chrostowski, José Azaña
We experimentally demonstrate high-performance integer and fractional-order photonic Hilbert transformers based on laterally apodized Bragg gratings in a silicon-on-insulator technology platform. The sub-millimeter-long gratings have been fabricated using single-etch electron beam lithography, and the resulting HT devices offer operation bandwidths approaching the THz range, with time-bandwidth products between 10 and 20.
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27804940/-estimation-of-the-diagnostic-potential-of-apod-ptov1-and-epha4-for-prostatic-neoplasms
#16
D O Allina, Yu Yu Andreeva, L E Zavalishina, L V Moskvina, G A Frank
: Prostate cancer is one of the most frequently detected malignancies in men. The gold standard for its diagnosis is morphological examination; at the same time the differential diagnosis of adenocarcinoma, high-grade prostatic intraepithelial neoplasia (HGPIN), and benign conditions that are able to mimic the malignancies is tremendously difficult in a number of cases, this being so, the hyperdiagnosis rate of HGPIN requiring mandatory repeat biopsy is as high as 24%. The currently available differential diagnostic panel of antibodies is imperfect, which necessitates a search for novel markers...
2016: Arkhiv Patologii
https://www.readbyqxmd.com/read/27766342/fine-tuning-of-optical-signals-in-nanoporous-anodic-alumina-photonic-crystals-by-apodized-sinusoidal-pulse-anodisation
#17
Abel Santos, Cheryl Suwen Law, Dominique Wong Chin Lei, Taj Pereira, Dusan Losic
In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures...
October 21, 2016: Nanoscale
https://www.readbyqxmd.com/read/27723581/high-frame-rate-high-resolution-ultrasound-imaging-with-multi-line-transmission-and-filtered-delay-multiply-and-sum-beamforming
#18
Giulia Matrone, Alessandro Ramalli, Alessandro Savoia, Piero Tortoli, Giovanni Magenes
Multi-Line Transmission (MLT) was recently demonstrated as a valuable tool to increase the frame rate of ultrasound images. In this approach, the multiple beams that are simultaneously transmitted may determine cross-talk artifacts that are typically reduced, although not eliminated, by the use of Tukey apodization on both transmission and reception apertures, which unfortunately worsens the image lateral resolution. In this paper we investigate the combination, and related performance, of Filtered-Delay Multiply And Sum (F-DMAS) beamforming with MLT for high frame-rate ultrasound imaging...
October 4, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27705857/a-comparison-of-the-performance-of-different-multiline-transmit-setups-for-fast-volumetric-cardiac-ultrasound
#19
Alejandra Ortega, Jean Provost, Ling Tong, Pedro Santos, Brecht Heyde, Mathieu Pernot, Jan D'hooge
It was previously demonstrated in 2-D echocardiography that a proper multiline transmit (MLT) implementation can be used to increase frame rate while preserving image quality. Initial findings for extending MLT to 3-D showed that it might address the low spatiotemporal resolution of current volumetric ultrasound systems. However, to date, it remains unclear how much transmit/receive parallelization would be possible using a 3-D MLT system. Therefore, the aim of this paper was to contrast different MLT setups for 3-D imaging by computer simulation in order to determine an optimal tradeoff between the amount of parallelization of an MLT system and the corresponding signal-to-noise ratio of the resulting images...
December 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27640368/analysis-of-apolipoprotein-genes-and-their-involvement-in-disease-response-of-channel-catfish-after-bacterial-infection
#20
Yujia Yang, Qiang Fu, Tao Zhou, Yun Li, Shikai Liu, Qifan Zeng, Xiaozhu Wang, Yulin Jin, Changxu Tian, Zhenkui Qin, Rex Dunham, Zhanjiang Liu
Apolipoproteins are protein component of plasma lipoproteins. They exert crucial roles in lipoprotein metabolism and serve as enzyme cofactors, receptor ligands, and lipid transfer carriers in mammals. In teleosts, apolipoproteins are also involved in diverse processes including embryonic and ontogenic development, liver and digestive system organogenesis, and innate immunity. In this study, we identified a set of 19 apolipoprotein genes in channel catfish (Ictalurus punctatus). Phylogenetic analysis and syntenic analysis were conducted to determine their identities and evolutionary relationships...
February 2017: Developmental and Comparative Immunology
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