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https://www.readbyqxmd.com/read/28438004/autofocusing-airy-beams-generated-by-all-dielectric-metasurface-for-visible-light
#1
Qingbin Fan, Daopeng Wang, Pengcheng Huo, Zijie Zhang, Yuzhang Liang, Ting Xu
Conventional method to generate autofocusing Airy (AFA) beam involves the optical Fourier transform (FT) system, which has a fairly long working distance due to the focal length of FT lens, presence of spatial light modulator (SLM) and auxiliary total reflection mirrors. Here, we propose an extremely compact design to generate high-efficiency AFA beam at visible frequency by using metasurface which is composed of a single layer array of amorphous titanium dioxide (TiO<sub>2</sub>) elliptical nanofins sitting on the fused-silica substrate...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437984/light-bullets-in-coupled-nonlinear-schr%C3%A3-dinger-equations-with-variable-coefficients-and-a-trapping-potential
#2
Si-Liu Xu, Guo-Peng Zhao, Milivoj R Belić, Jun-Rong He, Li Xue
We analyze three-dimensional (3D) vector solitary waves in a system of coupled nonlinear Schrödinger equations with spatially modulated diffraction and nonlinearity, under action of a composite self-consistent trapping potential. Exact vector solitary waves, or light bullets (LBs), are found using the self-similarity method. The stability of vortex 3D LB pairs is examined by direct numerical simulations; the results show that only low-order vortex soliton pairs with the mode parameter values n ≤ 1, l ≤ 1 and m = 0 can be supported by the spatially modulated interaction in the composite trap...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437968/vortex-energy-flows-generated-by-core-shell-nanospheres
#3
Shih-Wen Chen, Jia-Han Li
Investigated in this paper is the interaction of light and the nanospheres composed by a dielectric core with a gold-shell cladding that causes the optical vortices inside the core and the whirlpools around the shell. Different radius ratios, dimensions and the dielectric functions of nanospheres were studied using the finite-difference time-domain method. It was found that optical vortices were most likely to occur in the regions of increased absorption cross section and reduced scattering cross section. Two optical vortices of the opposite polarity, each centered in one of the particles of a dimer are created by a nanoshell dimer...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28435004/improvements-in-left-ventricular-diastolic-mechanics-after-parachute-device-implantation-in-patients-with-ischemia-heart-failure-a-cardiac-ct-study
#4
Chun-Ho Yun, Jing-Yi Sun, Barry Templin, Shih-Hsuan Lin, Kuan-Ming Chen, Tung-Hsin Wu, Chung-Lieh Hung, Chun-Chieh Liu, Hsi-Hsien Hsu, Mohamad Amer Alaiti, Anas Fares, Anthony DeCicco, Hiram G Bezerra
BACKGROUND: Percutaneous ventricular restoration therapy using left ventricle (LV) partitioning Parachute device has emerged as a clinical treatment option for LV apical aneurysm post extensive anterior myocardial infarction (AMI). We assessed changes of diastolic mechanics and accompanied functional improvements following LV parachute device implantation by cardiac computed tomography (CCT). METHODS AND RESULTS: CCT data from 28 patients in the pre- and post-implantation of LV parachute device implantation...
April 20, 2017: Journal of Cardiac Failure
https://www.readbyqxmd.com/read/28431851/ultraviolet-c-light-as-a-means-of-disinfecting-anesthesia-workstations
#5
Matthew Nottingham, Gene Peterson, Christopher Doern, Michelle Doll, Nadia Masroor, Kakotan Sanogo, Michael Stevens, Gonzalo Bearman
BACKGROUND: Anesthesia workstations (AWs) are a reservoir for pathogenic organisms potentially associated with surgical site infections. This study examined the effectiveness of the Tru-D SmartUVC device (Tru-D LLC, Nashville, TN) on bioburden reduction (BR) on AWs. METHODS: Strips of tissue inoculated with a known concentration of either Staphylococcus aureus, Enterococcus faecalis, or Acinetobacter sp were placed on 22 high-touch surfaces of an AW. Half of the AW surfaces received direct ultraviolet (UV) light exposure and half received indirect exposure...
April 18, 2017: American Journal of Infection Control
https://www.readbyqxmd.com/read/28430510/topologically-allowed-nonsixfold-vortices-in-a-sixfold-multiferroic-material-observation-and-classification
#6
Shaobo Cheng, Jun Li, Myung-Geun Han, Shiqing Deng, Guotai Tan, Xixiang Zhang, Jing Zhu, Yimei Zhu
We report structural transformation of sixfold vortex domains into two-, four-, and eightfold vortices via a different type of topological defect in hexagonal manganites. Combining high-resolution electron microscopy and Landau-theory-based numerical simulations, we investigate the remarkable atomic arrangement and the intertwined relationship between the vortex structures and the topological defects. The roles of their displacement field, formation temperature, and nucleation sites are revealed. All conceivable vortices in the system are topologically classified using homotopy group theory, and their origins are identified...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430463/electromagnetic-response-of-three-dimensional-topological-crystalline-insulators
#7
Srinidhi T Ramamurthy, Yuxuan Wang, Taylor L Hughes
Topological crystalline insulators are a new class of materials that have metallic surface states on select surfaces due to point group crystalline symmetries. In this Letter, we consider a model for a three-dimensional topological crystalline insulator with Dirac nodes occurring on a surface that are protected by the mirror symmetry. We demonstrate that the electromagnetic response for such a system is characterized by a 1-form b_{μ}. The value of b_{μ} can be inferred from the locations of the surface Dirac nodes in energy-momentum space...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430237/experimental-study-of-propagation-properties-of-vortex-beams-in-oceanic-turbulence
#8
Zhenglin Liu, Jialin Chen, Daomu Zhao
The intensity of vortex beams always changes on propagation through oceanic turbulence, which is influenced by parameters of turbulence. This property is usually researched only by numerical simulation. Recently, a new method with a spatial light modulator (SLM) can be used in a laboratory to show various turbulence, which makes it possible to construct a system of a beam passing through turbulence by experiment. We investigate a vortex beam propagating through oceanic turbulence with a spiral phase plate and SLM in the laboratory and obtain the intensity distribution images by a charge-coupled device...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28430234/dimensional-properties-of-laguerre-gaussian-vortex-beams
#9
Jie Zhang, Su-Juan Huang, Fu-Quan Zhu, Wei Shao, Mu-Sheng Chen
We derive and analyze the dimensional properties of Laguerre-Gaussian vortex beams theoretically and numerically. The analytical expressions of inner and outer radii are given out and proved to be proportional to the transverse beam size, when the topological charge remains. The ratio of the outer and inner radius only depends on the topological charge, having nothing to do with the waist radius and the propagation distance, and the ratio decreases as the topological charge increases. Using a spatial light modulator loaded with computer-generated holograms, we generate vortex beams...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28430209/singular-skeleton-of-a-laguerre-gaussian-beam-transformed-by-the-double-phase-ramp-converter
#10
Anna Khoroshun, Aleksey Chernykh, Julia Kirichenko, Oleksandr Ryazantsev, Aleksandr Bekshaev
We analyze transformations of circular Laguerre-Gaussian beams with zero radial index after passage through the double-phase-ramp (DPR) converter and study the behavior of optical vortices in the propagating transformed beam. Direct and inverse DPR converters are considered, and informative features of the complete set of optical vortices are revealed. For the input beam with even azimuthal index, such a reaction may cause the sign reversal of the axial optical vortex. The results can be used for creation of light beams with prescribed singular skeleton, for the beam diagnostics, and in high-resolution metrology...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28425393/magnetic-graphene-oxide-as-an-efficient-adsorbent-for-the-separation-and-preconcentration-of-cu-ii-pb-ii-and-cd-ii-from-environmental-samples
#11
Mustafa Soylak, Demet Acar, Erkan Yilmaz, Sherif A El-Khodary, Mohamed Morsy, Medhat Ibrahim
The separation and preconcentration of copper(II), lead(II), and cadmium(II) ions on magnetic graphene oxide (MGO) by solid-phase extraction was carried out. Quantitative recovery was obtained by adsorption of analytes on MGO at pH 6 and elution of 3 M HNO3 in 10% acetone. To optimize the presented method, the effects of various parameters-including pH, eluent conditions, and vortex time-were examined. Matrix effects were also investigated. Mean recoveries of the analytes were between 95 and 105%. The proposed method was validated by applying it to certified reference materials...
April 20, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28424470/atom-size-electron-vortex-beams-with-selectable-orbital-angular-momentum
#12
Darius Pohl, Sebastian Schneider, Paul Zeiger, Ján Rusz, Peter Tiemeijer, Sorin Lazar, Kornelius Nielsch, Bernd Rellinghaus
The decreasing size of modern functional magnetic materials and devices cause a steadily increasing demand for high resolution quantitative magnetic characterization. Transmission electron microscopy (TEM) based measurements of the electron energy-loss magnetic chiral dichroism (EMCD) may serve as the needed experimental tool. To this end, we present a reliable and robust electron-optical setup that generates and controls user-selectable single state electron vortex beams with defined orbital angular momenta...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28418506/an-improved-optical-flow-method-for-blood-velocimetry
#13
Zifeng Yang, Hongtao Yu, George P Huang, Bryan Ludwig
Detailed blood velocity map in vascular system can be obtained by applying the optical flow method (OFM) in processing fluoroscopic digital subtracted catheter angiographic images, however, there are still challenges with the accuracy of this method. In the present study, a divergence compensatory Optical Flow Method (DC-OFM), in which a non-zero divergence of velocity is assumed due to the finite resolution of the image, was explored and applied to the digital subtraction angiography (DSA) images of blood flow...
April 17, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28418157/effect-of-canal-preparation-with-trushape-and-vortex-rotary-instruments-on-three-dimensional-geometry-of-oval-root-canals
#14
Ana Arias, Frank Paqué, Stephanie Shyn, Sarah Murphy, Ove A Peters
The purpose of this study was to assess the geometry of non-round root canals after preparation with TRUShape (a novel instrument with s-shaped longitudinal design) in comparison to conventional rotary instrumentation using micro-computed tomography. Twenty distal root canals of mandibular molars were randomly distributed in two groups to be shaped with either TRUShape or Vortex rotaries. Percentages of unprepared surface and volume of dentin removal for the entire canal and for the apical 4 mm were calculated...
April 18, 2017: Australian Endodontic Journal: the Journal of the Australian Society of Endodontology Inc
https://www.readbyqxmd.com/read/28416394/moderate-reagent-mixing-on-an-orbital-shaker-reduces-the-incubation-time-of-enzyme-linked-immunosorbent-assay
#15
Saroj Kumar, Rajesh Ahirwar, Ishita Rehman, Pradip Nahar
Rapid diagnostic tests can be developed using ELISA for detection of diseases in emergency conditions. Conventional ELISA takes 1-2 days, making it unsuitable for rapid-diagnostics. Here, we report the effect of reagents mixing via shaking or vortexing on the assay timing of ELISA. A 48-min protocol of ELISA involving 12-min incubations with reagent mixing at 750 rpm of for every step was optimized. Contrary to this, time-optimized control ELISA performed without mixing produced similar results in 8 h, leaving a time gain of 7 h using the developed protocol...
April 14, 2017: Analytical Biochemistry
https://www.readbyqxmd.com/read/28415333/melting-of-a-nonequilibrium-vortex-crystal-in-a-fluid-film-with-polymers-elastic-versus-fluid-turbulence
#16
Anupam Gupta, Rahul Pandit
We perform a direct numerical simulation of the forced, incompressible two-dimensional Navier-Stokes equation coupled with the FENE-P equations for the polymer-conformation tensor. The forcing is such that, without polymers and at low Reynolds numbers Re, the film attains a steady state that is a square lattice of vortices and antivortices. We find that, as we increase the Weissenberg number Wi, a sequence of nonequilibrium phase transitions transforms this lattice, first to spatially distorted, but temporally steady, crystals and then to a sequence of crystals that oscillate in time, periodically, at low Wi, and quasiperiodically, for slightly larger Wi...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415321/sedimentation-equilibrium-of-magnetic-nanoparticles-with-strong-dipole-dipole-interactions
#17
Andrey A Kuznetsov, Alexander F Pshenichnikov
Langevin dynamics simulation is used to study the suspension of interacting magnetic nanoparticles (dipolar spheres) in a zero applied magnetic field and in the presence of a gravitational (centrifugal) field. A particular emphasis is placed on the equilibrium vertical distribution of particles in the infinite horizontal slab. An increase in the dipolar coupling constant λ (the ratio of dipole-dipole interaction energy to thermal energy) from zero to seven units causes an increase in the particle segregation coefficient by several orders of magnitude...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415312/nonlinear-effects-in-the-bounded-dust-vortex-flow-in-plasma
#18
Modhuchandra Laishram, Devendra Sharma, Prabal K Chattopdhyay, Predhiman K Kaw
The vortex structures in a cloud of electrically suspended dust in a streaming plasma constitutes a driven system with a rich nonlinear flow regime. Experimentally recovered toroidal formations of this system have motivated study of its volumetrically driven-dissipative vortex flow dynamics using two-dimensional hydrodynamics in the incompressible Navier-Stokes regime. Nonlinear equilibrium solutions are obtained for this system where a nonuniformly driven two-dimensional dust flow exhibits distinct regions of localized accelerations and strong friction caused by stationary fluids at the confining boundaries resisting the dust flow...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415270/pinning-of-scroll-waves-to-flat-and-highly-branched-unexcitable-heterogeneities
#19
Dhriti Mahanta, Sumana Dutta, Oliver Steinbock
System heterogeneities such as organelles, cells, and anatomical features strongly affect nonlinear wave patterns in biological systems. These effects are more readily studied in otherwise homogeneous chemical reactions that allow the introduction of tailored structures. Following this approach, we investigate the dynamics of three-dimensional excitation vortices pinned to inert sheets with circular holes arranged on a hexagonal lattice. Experiments with the Belousov-Zhabotinsky reaction and numerical simulations of an excitable reaction-diffusion model reveal vortex pinning that circumvents the rapid collapse of free vortex rings...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415211/dynamics-of-vortex-antivortex-pairs-and-rarefaction-pulses-in-liquid-light
#20
David Feijoo, Angel Paredes, Humberto Michinel
We present a numerical study of the cubic-quintic nonlinear Schrödinger equation in two transverse dimensions, relevant for the propagation of light in certain exotic media. A well-known feature of the model is the existence of flat-top bright solitons of fixed intensity, whose dynamics resembles the physics of a liquid. They support traveling wave solutions, consisting of rarefaction pulses and vortex-antivortex pairs. In this work, we demonstrate how the vortex-antivortex pairs can be generated in bright soliton collisions displaying destructive interference followed by a snake instability...
March 2017: Physical Review. E
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