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Jia-Sheng Ye, Li-Juan Xie, Xin-Ke Wang, Sheng-Fei Feng, Wen-Feng Sun, Yan Zhang
We present a new feasible way to flatten the axial intensity oscillations for diffraction of a finite-sized Bessel beam, through designing a cardioid-like hole. The boundary formula of the cardioid-like hole is given analytically. Numerical results by the complete Rayleigh-Sommerfeld method reveal that the Bessel beam propagates stably in a considerably long axial range, after passing through the cardioid-like hole. Compared with the gradually absorbing apodization technique in previous papers, in this paper a hard truncation of the incident Bessel beam is employed at the cardioid-like hole edges...
January 22, 2018: Optics Express
Moshe Zadka, You-Chia Chang, Aseema Mohanty, Christopher T Phare, Samantha P Roberts, Michal Lipson
Current silicon photonics phased arrays based on waveguide gratings enable beam steering with no moving parts. However, they suffer from a trade-off between beam divergence and field of view. Here, we show a platform based on silicon-nitride/silicon that achieves simultaneously minimal beam divergence and maximum field of view while maintaining performance that is robust to fabrication variations. In addition, in order to maximize the emission from the entire length of the grating, we design the grating's strength by varying its duty cycle (apodization) to emit uniformly...
February 5, 2018: Optics Express
Zhaolou Cao, Chunjie Zhai, Shanshan Xu, Yunyun Chen
Bessel beams have been increasingly used for their advantages of non-diffraction and long focal depth. In this paper, we studied the propagation of on-axis and off-axis Bessel beams in a gradient-index medium. By expressing a Bessel beam in integral form, the analytical expression of an on-axis, decentered, and tilted Bessel beam through a paraxial optical system is derived with the ABCD matrix method and Collins diffraction integral formula. Main lobe size and trajectory of the zeroth- and second-order Bessel beam are obtained, demonstrating that the Bessel beam is focused by the gradient-index medium and its main lobe trajectory is exactly the same as the corresponding geometrical ray for both the decentered and tilted Bessel beam...
February 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Wei Zhang, Yang Wu, Hai-Jiao Dong, Jun-Jie Yin, Hui Zhang, Hao-An Wu, Li-Na Song, Yu Chong, Zhuo-Xuan Li, Ning Gu, Yu Zhang
Herein we reported Prussian blue nanoparticles (PBNPs) possess ascorbic acid oxidase (AAO)- and ascorbic acid peroxidase (APOD)-like activities, which suppressed the formation of harmful H2O2 and finally inhibited the anti-cancer efficiency of ascorbic acid (AA). This newly revealed correlation between iron and AA could provide new insight for the studies of nanozymes and free radical biology.
January 11, 2018: Colloids and Surfaces. B, Biointerfaces
Nazmi A Mohammed, Hatem O El Serafy
This work targets a remarkable quasi-distributed temperature sensor based on an apodized fiber Bragg grating. To achieve this, the mathematical formula for a proposed apodization function is carried out and tested. Then, an optimization parametric process required to achieve the remarkable accuracy that is based on coupled mode theory (CMT) is done. A detailed investigation for the side lobe analysis, which is a primary judgment factor, especially in quasi-distributed configuration, is investigated. A comparison between elite selection of apodization profiles (extracted from related literatures) and the proposed modified-Nuttal profile is carried out covering reflectivity peak, full width half maximum (FWHM), and side lobe analysis...
January 10, 2018: Applied Optics
Tao Liu, Lingjie Wang, Jizhen Zhang, Qiang Fu, Xin Zhang
In this paper, we investigate the relationship between open-ring zones of the Fresnel zone plate and the pinhole rings of photon sieves (PSs). Numerical simulations show that the normalized diffraction fields near the focal point of an individual pinhole ring and the circular open-ring zone are the same. It is confirmed that the maximum diffraction efficiency of an open-ring zone is higher than that of the traditional pinhole ring. Meanwhile, pinhole rings have more flexibility for apodization filtering. Based on these key findings, we propose the design theory of an apodized diffractive optical element comprised of open-ring zones and pinholes...
January 1, 2018: Applied Optics
Nadia García-Mateo, Raquel Pascua-Maestro, Alberto Pérez-Castellanos, Concepción Lillo, Diego Sanchez, Maria D Ganfornina
To compact the extracellular sides of myelin, an important transition must take place: from membrane sliding, while building the wraps, to membrane adhesion and water exclusion. Removal of the negatively charged glycocalyx becomes the limiting factor in such transition. What is required to initiate this membrane-zipping process? Knocking-out the Lipocalin Apolipoprotein D (ApoD), essential for lysosomal functional integrity in glial cells, results in a specific defect in myelin extracellular leaflet compaction in peripheral and central nervous system, which results in reduced conduction velocity and suboptimal behavioral outputs: motor learning is compromised...
December 9, 2017: Glia
Yulong Wang, Lijuan Xie, Jiasheng Ye, Wenfeng Sun, Xinke Wang, Shengfei Feng, Peng Han, Qiang Kan, Yan Zhang
We demonstrated a simple heart-shaped hole to tailor the axial intensity of a collimated laser beam. This hole is transformed from a soft-boundary one, which avoids the difficulty in fabricating the soft-boundary mask designed by the apodization method, as well as the interference problem caused by the pixel structure of the spatial light modulator. When a collimated light passes through this hole, its axial intensity oscillates less than 11% within a certain distance, while the fluctuation after the circular aperture is up to 200%...
December 1, 2017: Optics Letters
Henrik Enghoff, Laura Mark Jensen, Elena V Mikhaljova
A unique pattern of missing defence glands on certain body rings is described for two species of the millipede family Mongoliulidae, order Julida: Ussuriiulus pilifer Golovatch, 1980, and Koiulus interruptus Enghoff et al., 2017. Based on the patterns of missing glands observed in recently collected samples of the two species, numbers of podous and apodous body rings in successive stadia of the postembryonic development can be inferred for each individual millipede, which in turn allows the reconstruction of pathways of anamorphosis in these species...
November 30, 2017: Arthropod Structure & Development
Riccardo Marchetti, Cosimo Lacava, Ali Khokhar, Xia Chen, Ilaria Cristiani, David J Richardson, Graham T Reed, Periklis Petropoulos, Paolo Minzioni
We present a simple and practical strategy that allows to design high-efficiency grating couplers. The technique is based on the simultaneous apodization of two structural parameters: the grating period and the fill-factor, along with the optimization of the grating coupler etching depth. Considering a 260 nm Si-thick Silicon-on-insulator platform, we numerically demonstrated a coupling efficiency of -0.8 dB (83%), well matching the experimental value of -0.9 dB (81%). Thanks to the optimized design, these results represent the best performance ever reported in the literature for SOI structures without the use of any back-reflector...
November 30, 2017: Scientific Reports
Saritha Kosarussavadi, Zachary T Pennington, Jeremy Covell, Aaron P Blaisdell, Barney A Schlinger
Age-related decrements in cognitive ability have been proposed to stem from deteriorating function of the hippocampus. Many birds are long lived, especially for their relatively small body mass and elevated metabolism, making them a unique model of resilience to aging. Nevertheless, little is known about avian age-related changes in cognition and hippocampal physiology. We studied spatial cognition and hippocampal expression of the age-related gene, Apolipoprotein D (ApoD), and the immediate early gene Egr-1 in zebra finches at various developmental time points...
December 2017: Behavioral Neuroscience
Puhong Zhang, Jialin Gao, Chun Pu, Yao Zhang
Dyslipidaemia in type 2 diabetes mellitus (T2DM) is characterized by high plasma triglyceride concentrations, reduced high‑density lipoprotein concentrations and increased small density low‑density lipoprotein concentrations. Dyslipidaemia may lead to cardiovascular disease (CVD) and other complications. Apolipoproteins mainly comprise six species, apolipoprotein (apo)A, apoB, apoC, apoD, apoE and apoM, which are important components of plasma lipoproteins that carry lipids and stabilize the structure of lipoproteins...
October 19, 2017: Molecular Medicine Reports
Stefano Mandija, Alessandro Sbrizzi, Ulrich Katscher, Peter R Luijten, Cornelis A T van den Berg
PURPOSE: MR electrical properties tomography (MR-EPT) aims to measure tissue electrical properties by computing spatial derivatives of measured B1+ data. This computation is very sensitive to spatial fluctuations caused, for example, by noise and Gibbs ringing. In this work, the error arising from the computation of spatial derivatives using finite difference kernels (FD error) has been investigated. In relation to this FD error, it has also been investigated whether mitigation strategies such as Gibbs ringing correction and Gaussian apodization can be beneficial for conductivity reconstructions...
November 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Xiaodong Wang, Bo Chen
Dual-band cold mirrors are designed based on third-order of 121.6 nm multilayers, and they are only composed of LaF3 and MgF2. The designed mirrors have a high reflectance at 121.6 nm and 280 nm, and a low reflectance in visible waveband; they also have a narrow bandwidth of 4 nm at 121.6 nm, and low sidelobe ripples of two stopbands. A broadband antireflection coating and an asymmetrically Gaussian-apodization of thickness-modulated design method are proposed to eliminate sidelobe ripples of the reflection zone...
November 13, 2017: Scientific Reports
Mohammad Mahdi Shanei, Mahdieh Hashemi, Davood Fathi, Carlos J Zapata-Rodríguez
High-index silicon nanoblocks support excitation of both electric and magnetic resonance modes at telecommunication wavelengths. At frequencies where both electric and magnetic resonance modes are excited simultaneously, changing the geometrical dimensions of the silicon cubes creates a 2π full span over the phase of the transmitted light in different amplitude ranges. We take advantage of the additional power-flux modulation of the scattered signal to focus the incident light with desired full width at half maximum (FWHM) and side lobe levels (SLLs) in both the lateral and axial directions...
November 10, 2017: Applied Optics
Yanyan Zhou, Li Wang, Rongqiao Li, Minmin Liu, Xiaotong Li, Hang Su, Yusong Xu, Huabing Wang
Recent studies highlighted that apolipoprotein D (ApoD) and its homologs exert neuroprotective and antioxidant functions in mammals and Drosophila. Unlike mammals and Drosophila, lepidopteran insects possess three distinct ApoD homologs. However, few information on their functions in lepidopteran insects are available. In this study, we investigated the protective potential of a novel ApoD homolog, BmApoD1, in Bombyx mori. Quantitative PCR analyses demonstrated that BmApoD1 is extensively expressed at low levels during the larval stage but abundantly expressed in the testis during the pupal and adult stages...
November 8, 2017: Biochemical and Biophysical Research Communications
Christopher T Nadovich, William D Jemison, Derek J Kosciolek, David T Crouse
The forked grating coupler (FGC) is an optical vortex interface for silicon photonics. Using the structure of a Bragg grating coupler with a calculated forked hologram, the FGC couples optical vortex modes into confined waveguide modes of a photonic integrated circuit. Design methodologies are given, as well as measured performance data from fabricated devices. Data are analyzed with a variety of metrics. The effectiveness of design features are evaluated. Advanced FGC designs are demonstrated with focused forked gratings, allowing feed length to be reduced, and with apodization improving vortex mode fidelity...
October 30, 2017: Optics Express
Zhengyun Zhang, Chenglong Bao, Hui Ji, Zuowei Shen, George Barbastathis
A sensor pixel integrates optical intensity across its extent, and we explore the role that this integration plays in phase space tomography. The literature is inconsistent in its treatment of this integration-some approaches model this integration explicitly, some approaches are ambiguous about whether this integration is taken into account, and still some approaches assume pixel values to be point samples of the optical intensity. We show that making a point-sample assumption results in apodization of and thus systematic error in the recovered ambiguity function, leading to underestimating the overall degree of coherence...
November 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Jianfei Jiang, Huiye Qiu, Gencheng Wang, Yan Li, Tingge Dai, Debin Mu, Hui Yu, Jianyi Yang, Xiaoqing Jiang
A lateral-apodized add-drop filter is demonstrated in a multimode asymmetric waveguide Bragg grating. This design utilizes two individual superposed gratings with the same sidewall corrugation depth. The strong side lobes of the grating filter are efficiently suppressed by mapping the target apodization profile into lateral shifts between the periods of the two gratings. Compared with other apodized technology, this device is easier to be realized. Experimental results show that the side-lobes suppression ratio can reach 18...
October 20, 2017: Applied Optics
Brian Vohnsen, Alessandra Carmichael, Najnin Sharmin, Salihah Qaysi, Denise Valente
The integrated Stiles-Crawford function is commonly used as apodization model for vision through the natural eye pupil. However, this method does not account for possible effects related to the retinal thickness, the large length-to-diameter aspect ratio of the photoreceptors, or the use of nonMaxwellian illumination. Here, we introduce a geometrical optics model to calculate the fraction of overlap between light at the retina and the photoreceptor outer segments where absorption triggers vision. The model, which does not account for photoreceptor waveguiding, is discussed for both Maxwellian and nonMaxwellian illumination...
October 1, 2017: Journal of Vision
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