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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
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
Alejandra Ortega, Jean Provost, Ling Tong, Pedro Santos, Brecht Heyde, Mathieu Pernot, Jan D'hooge
It was previously demonstrated in 2D echocardiography that a proper multi-line transmit (MLT) implementation can be used to increase frame rate while preserving image quality. Initial findings for extending MLT to 3D 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 3D MLT system. Therefore, the aim of this study was to contrast different MLT setups for 3D imaging by computer simulation in order to determine an optimal trade-off between the amount of parallelization of a MLT system and the corresponding signal-to-noise ratio of the resulting images...
September 29, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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...
September 15, 2016: Developmental and Comparative Immunology
Marcony R Santhiago, Bruna V Ventura, Ramon C Ghanem, Newton Kara-Junior, Haroldo V Moraes, Emir Ghanem
PURPOSE: To investigate potential differences in predictability, efficacy, and safety of corneal excimer laser to correct residual myopia, hyperopia, and astigmatism in eyes previously implanted with multifocal intraocular lenses using distinct optical surfaces and platforms for multifocality. METHODS: This prospective comparative study included 37 eyes submitted to laser in situ keratomileusis correction for residual errors after implantation of either an apodized diffractive-refractive (Restor) or a full-diffractive (Tecnis) multifocal intraocular lens...
November 2016: Cornea
N C Hornig, M Ukat, H U Schweikert, O Hiort, R Werner, S L S Drop, M Cools, I A Hughes, L Audi, S F Ahmed, J Demiri, P Rodens, L Worch, G Wehner, A E Kulle, D Dunstheimer, E Müller-Roßberg, T Reinehr, A T Hadidi, A K Eckstein, C van der Horst, C Seif, R Siebert, O Ammerpohl, P-M Holterhus
CONTEXT: Only about 85% of patients with clinical diagnosis complete androgen insensitivity syndrome (CAIS) and less than 30% with partial androgen insensitivity syndrome (PAIS) can be explained by inactivating mutations in the androgen receptor (AR) gene. OBJECTIVE: To clarify this discrepancy by in-vitro determination of AR transcriptional activity in individuals with disorders of sex development (DSD) and male controls. DESIGN: Quantification of dihydrotestosterone (DHT)-dependent transcriptional induction of the AR target gene apolipoprotein D (APOD) in cultured genital fibroblasts (GF) (APOD-assay) and next generation sequencing (NGS) of the complete coding - and non-coding AR-locus...
September 1, 2016: Journal of Clinical Endocrinology and Metabolism
W Lim, H Bae, G Song
Apolipoprotein D, a 29-kDa secreted glycoprotein that belongs to the lipocalin superfamily, is widely expressed in various tissues and associated with lipid metabolism as a component of high-density lipoproteins. Although Apolipoprotein D binds to small hydrophobic ligands including cholesterol, little is known about effects of high-fat diet with cholesterol on expression of Apolipoprotein D in the male reproductive tract. Therefore, we investigated Apod expression in penises, prostate glands, and testes from rats fed a high-fat diet including a high amount of cholesterol...
August 27, 2016: Andrology
Zhengwei Zhou, Xiaoming Bi, Janet Wei, Hsin-Jung Yang, Rohan Dharmakumar, Reza Arsanjani, C Noel Bairey Merz, Debiao Li, Behzad Sharif
PURPOSE: The presence of subendocardial dark-rim artifact (DRA) remains an ongoing challenge in first-pass perfusion (FPP) cardiac magnetic resonance imaging (MRI). We propose a free-breathing FPP imaging scheme with Cartesian sampling that is optimized to minimize the DRA and readily enables near-instantaneous image reconstruction. MATERIALS AND METHODS: The proposed FPP method suppresses Gibbs ringing effects-a major underlying factor for the DRA-by "shaping" the underlying point spread function through a two-step process: 1) an undersampled Cartesian sampling scheme that widens the k-space coverage compared to the conventional scheme; and 2) a modified parallel-imaging scheme that incorporates optimized apodization (k-space data filtering) to suppress Gibbs-ringing effects...
August 17, 2016: Journal of Magnetic Resonance Imaging: JMRI
Junseob Shin, Yu Chen, Harshawn Malhi, Jesse 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 multi-phase apodization with cross-correlation (MPAX), which is an improved version of our previous technique, DAX...
August 2, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Shankarappa Manjunatha, Klaus Distelmaier, Surendra Dasari, Rickey E Carter, Yogish C Kudva, K Sreekumaran Nair
OBJECTIVE: Higher HDL-cholesterol (HDL-C) is linked to lower cardiovascular risk but individuals with type 1 diabetes mellitus (T1DM) with normal or high HDL-C have higher cardiovascular events compared to age matched non-diabetic controls (ND). We determined whether altered HDL functions despite having normal HDL-C concentration may explain increased cardiovascular risk in T1DM individuals. We also determined whether irreversible posttranslational modifications (PTMs) of HDL bound proteins occur in T1DM individuals with altered HDL functions...
September 2016: Metabolism: Clinical and Experimental
Corine Martineau, Ouafa Najyb, Céline Signor, Éric Rassart, Robert Moreau
BACKGROUND: Apolipoprotein D (ApoD) is a member of the lipocalin family known to transport small hydrophobic ligands. A major site of ApoD expression in mice is the central nervous system where evidence suggests that it plays a protective role. Gene expression of ApoD was reported in bone-forming osteoblasts but its impact on bone metabolism remains undocumented. METHODS: We compared basic bone parameters of ApoD(-/-) (null) and transgenic (tg) mice to wild-type (wt) littermates through microCT and histochemistry, as well as ApoD expression and secretion in osteoblasts under various culture conditions through real-time PCR and immunoblotting...
September 2016: Metabolism: Clinical and Experimental
Jim Schwiegerling
Efficient coding enables rapid calculation of basis functions for a linear expansion of the optical transfer function.
August 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
José A Díaz
In a recent paper [J. Opt. Soc. Am. A31, 2476 (2014)JOAOD60740-323210.1364/JOSAA.31.002476], a linear expansion of the optical transfer function (OTF) of an imaging system in which the expansion coefficients are related to its wavefront errors has been developed. It is claimed that the OTF can be calculated quickly by using this approach. We provide instead closed-form basis functions that are not determined recursively. Numerical examples demonstrate that the OTF calculation by a digital autocorrelation of the pupil function is much faster regardless of the wavefront complexity...
August 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Thanh Nguyen, George Nehmetallah, Christopher Raub, Scott Mathews, Rola Aylo
In this work, we investigate, both theoretically and experimentally, single-wavelength and multiwavelength digital holographic microscopy (DHM) using telecentric and nontelecentric configurations in transmission and reflection modes. A single-wavelength telecentric imaging system in DHM was originally proposed to circumvent the residual parabolic phase distortion due to the microscope objective (MO) in standard nontelecentric DHM configurations. However, telecentric configurations cannot compensate for higher order phase aberrations...
July 20, 2016: Applied Optics
Kengyeh K Chu, Carolin Unglert, Tim N Ford, Dongyao Cui, Robert W Carruth, Kanwarpal Singh, Linbo Liu, Susan E Birket, George M Solomon, Steven M Rowe, Guillermo J Tearney
We have designed and fabricated a 4 mm diameter rigid endoscopic probe to obtain high resolution micro-optical coherence tomography (µOCT) images from the tracheal epithelium of living swine. Our common-path fiber-optic probe used gradient-index focusing optics, a selectively coated prism reflector to implement a circular-obscuration apodization for depth-of-focus enhancement, and a common-path reference arm and an ultra-broadbrand supercontinuum laser to achieve high axial resolution. Benchtop characterization demonstrated lateral and axial resolutions of 3...
July 1, 2016: Biomedical Optics Express
Daniel Benedikovic, Carlos Alonso-Ramos, Pavel Cheben, Jens H Schmid, Shurui Wang, Robert Halir, Alejandro Ortega-Moñux, Dan-Xia Xu, Laurent Vivien, Jean Lapointe, Siegfried Janz, Milan Dado
We report, for the first time, on the design and experimental demonstration of fiber-chip surface grating couplers based on subwavelength grating engineered nanostructure operating in the low fiber chromatic dispersion window (around 1.3 μm wavelengths), which is of great interest for short-reach data communication applications. Our coupler designs meet the minimum feature size requirements of large-volume deep-ultraviolet stepper lithography processes. The fiber-chip couplers are implemented in a standard 220-nm-thick silicon-on-insulator (SOI) platform and are fabricated by using a single etch process...
June 13, 2016: Optics Express
A S Shcherbakov, A O Arellanes
New physical details inherent in the non-collinear two-phonon Bragg light scattering controlled by ultrahigh frequency elastic waves of finite amplitude are studied in wide-aperture crystals exhibiting moderate linear acoustic losses. Recently, it had been demonstrated that the Bragg regime of light scattering exhibits the specific acousto-optical non-linearity with a set of unit-level maxima. Now, additionally to our previous analysis, we present an advanced analytical description of this phenomenon in the amplitude and frequency domains, and what is more, we orient it mainly at the second unit-level maximum...
June 20, 2016: Applied Optics
Shujie Chen, Kevin J Parker
Many pulse-echo imaging systems use focused beams to improve lateral resolution. The beam width is determined by the choice of source and apodization function, the frequency, and the physics of focusing. Postprocessing strategies to improve lateral resolution can be limited by the need for conditioning the mathematics of inverse filtering, due to instabilities. We present an analysis that defines key constraints on sampled versions of lateral beampatterns. Within these constraints are useful symmetric beampatterns, which, when properly sampled, can have a stable inverse filter...
April 2016: Journal of Medical Imaging
Branislav Holländer, Gijs A G M Hendriks, Ritse M Mann, Hendrik H G Hansen, Chris L de Korte
The goal of this study was to assess whether it is viable to implement plane-wave imaging in the Automated Breast Volume Scanner (ABVS) to speed up the acquisition process. This would allow breath-hold examinations, thus reducing breathing artifacts without loss of imaging quality. A calibration phantom was scanned in an Automated Breast Volume Scanner-mimicking setup using both dynamic receive focusing with a fixed transmit focus and unfocused plane-wave compounding. Contrast-to-noise ratio and lateral resolution were compared using two beamforming schemes, delay-and-sum and Stolt's f-k algorithm...
October 2016: Ultrasound in Medicine & Biology
Pei-yue Xie, Jian-feng Yang, Bin Xue, Juan Lü, Ying-hong He, Ting Li, Xiao-long Ma
Interference imaging spectrometer is one of the most important equipments of Chang'E 1 satellite, which is applied to analysis the material composition and its distribution of the surface on the moon. At present, the spectral resolution of level 2B scientific data obtained by existing methods is 325 cm(-1). If we use the description way of wavelength resolution, various spectrum is different: the first band is 7.6 nm, the last band is 29 nm, which introduces two questions: (1) the spectral resolution description way mismatch with the way of ground spectral library used for calibration and comparison; (2) The signal-to-noise ratio of the spectra in the shortwave band is low due to the signal entering narrow band is little...
March 2016: Guang Pu Xue Yu Guang Pu Fen Xi, Guang Pu
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