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Sample records for einzel lens system

  1. Demonstrating H- beam focusing using an elliptical einzel lens

    Science.gov (United States)

    Lawrie, S. R.; Faircloth, D. C.; Letchford, A. P.; Whitehead, M. O.; Wood, T.

    2017-08-01

    H- ion source research is being performed at the ISIS spallation neutron and muon facility on a dedicated Vessel for Extraction and Source Plasma Analyses (VESPA). The ion extraction and optics system presently being used on ISIS is centered on a combined-function sector dipole magnet. This traps cesium vapor escaping the ion source; mass-separates co-extracted electrons and stripped neutrals, and weak-focusses the highly asymmetric slit-shaped ion beam. Unfortunately the added drift length through the magnet under strong space-charge forces means up to 50% of the beam is collimated on the magnet. The VESPA has shown that the ISIS ion source actually produces 80 mA of beam current at standard settings, but because of magnet collimation only 55 mA is injected into the solenoid Low Energy Beam Transport (LEBT). A new purely electrostatic post-extraction system incorporating an einzel lens with an elliptical aperture is currently under test. This allows much greater flexibility of perveance and phase space matching for injection into the LEBT and Radio Frequency Quadrupole (RFQ). This paper discusses high voltage breakdown mitigation strategies and presents the first results of the novel elliptical transport system. So far, 70 mA of beam has been transported through the new system with a normalized transverse RMS emittance of 0.2 π mm mrad.

  2. A magnetized Einzel lens electron dump for the Linac4 H− ion source

    CERN Document Server

    Midttun, O; Kronberger, M; Lettry, J; Pereira, H; Scrivens, R

    2013-01-01

    Linac4 is a 160 MeV linear accelerator which will inject negative hydrogen ions (H−) into CERN’s Proton Synchrotron Booster, a required upgrade to improve the beam brightness in the LHC injector chain. A volume production RF ion source, based on the design of the DESY RF source was implemented, but showed considerable electron dump ablation during operation at 45 keV beam energy. To reduce the electron beam power density in the dump, a magnetized Einzel lens is designed that reduces the beam energy to 10 keV before permanentmagnets dump the electrons on a tungsten surface. Presented in this paper are simulations of the design using IBSimu, the tunable range of parameters depending on the extracted H− and electron current, as well as details of the implementation, the choice of pulsed power converters and the electrode alignment system. In addition, simulations of proton extraction from this source will be shown.

  3. Einzel lens chopper and behavior of the chopped beam in the KEK digital accelerator

    Directory of Open Access Journals (Sweden)

    K. W. Leo

    2013-04-01

    Full Text Available The KEK digital accelerator (KEK-DA, which is a small-scale rapid-cycle induction synchrotron (IS, has commenced operation. A permanent magnet x-band electron cyclotron resonance ion source serves as the KEK-DA ion source and delivers various ions. A new Einzel lens beam chopper has been developed to provide the necessary pulse width of a few microseconds. The chopper is implemented by applying a rectangular pulse voltage generated by a solid-state Marx generator to the middle electrode of the Einzel lens. Momentum modulation at the bunch head and tail resulting from chopping in longitudinal direction has been observed. This intrinsic property of the chopped pulse has been clearly observed in a long drift (a free run in the circular ring in KEK-DA.

  4. Automated Fresnel lens tester system

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, G.S.

    1981-07-01

    An automated data collection system controlled by a desktop computer has been developed for testing Fresnel concentrators (lenses) intended for solar energy applications. The system maps the two-dimensional irradiance pattern (image) formed in a plane parallel to the lens, whereas the lens and detector assembly track the sun. A point detector silicon diode (0.5-mm-dia active area) measures the irradiance at each point of an operator-defined rectilinear grid of data positions. Comparison with a second detector measuring solar insolation levels results in solar concentration ratios over the image plane. Summation of image plane energies allows calculation of lens efficiencies for various solar cell sizes. Various graphical plots of concentration ratio data help to visualize energy distribution patterns.

  5. Cyclotron axial ion-beam-buncher system

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, R.W.; Swenson, D.A.; Wangler, T.P.

    1982-02-11

    Adiabatic ion bunching is achieved in a cyclotron axial ion injection system through the incorporation of a radio frequency quadrupole system, which receives ions from an external ion source via an accelerate-decelerate system and a focusing einzel lens system, and which adiabatically bunches and then injects the ions into the median plane of a cyclotron via an electrostatic quadrupole system and an inflection mirror.

  6. Solar powered desalination system using Fresnel lens

    Science.gov (United States)

    Sales, M. T. B. F.

    2016-11-01

    The Philippines is surrounded by coastal areas and these areas can be a potential source for potable water. This study aims to design and construct a solar powered desalination system using Fresnel lens. The experimental study was conducted using polluted salt water for the sample and desalination was carried out using the designed system. The desalination system was composed of the solar concentrator, solar still and the condenser system. The Fresnel lens was made of acrylic plastic and was an effective solar concentrator. Solar stills made of dark colored glass bottles were effective in absorbing the solar energy. The condenser system made of polybutylene and polystyrene were effective in condensing the vapor at ambient temperature. The shortest time of vaporization of the salt water was at 293 sec and the optimum angle of position of the lens was 36.42°. The amount of condensate collected was directly proportional to the amount of salt water in the solar still. The highest mean efficiency of the designed set-up was 34.82%. The water produced by the solar powered desalination system using Fresnel lens passed the standards set by WHO (World Health Organization) for drinking water.

  7. Zoom optical system using tunable polymer lens

    Science.gov (United States)

    Liang, Dan; Wang, Xuan Yin

    2016-07-01

    This paper demonstrated a zoom optical system with variable magnification based on the tunable polymer lens. The designed system mainly consists of two polymer lenses, voice coil motors, a doublet lens and CMOS chip. The zoom magnification can be adjusted by altering the focal length of the two elastic polymer lenses synergistically through controlling the output displacement of the voice coil motor. A static doublet lens in combination with the polymer lenses stabilize the image plane at the CMOS chip. The optical structure of the zoom system is presented, as well as a detailed description including the lens materials and fabrication process. Images with each zoom magnification are captured, and the Spot diagram and MTF are simulated using Zemax software. A change in magnification from 0.13×to 8.44×is demonstrated within the tiny 0.4 mm variation of the displacement load, and produce a 16.1×full range of magnification experimentally. Simulation analyses show that all the radii of the spot diagram under different magnifications are less than 11.3 um, and the modulation transfer function reaches 107 line pairs per mm. The designed optical system shows the potential for developing stable, integrated, and low-cost zoom systems with large magnification range.

  8. A Novel Fisheye-Lens-Based Photoacoustic System

    Directory of Open Access Journals (Sweden)

    Hojong Choi

    2016-12-01

    Full Text Available This paper presents a novel fisheye-lens-based photoacoustic (PA system. In conventional PA systems, mechanical motors are utilized to obtain the target information due to the small fields of view of such systems. The use of such motors introduces mechanical noise, which is difficult to remove when processing the echo signals. A fisheye lens system offering a wide field of view would effectively reduce the motor effects (i.e., the noise and enable the system to have a wide field of view. Therefore, in this work, we propose a novel fisheye lens scheme and describe a PA system based on the developed lens scheme. In addition, to confirm the feasibility of the fisheye-lens-based PA system, we present the typical pulse-echo responses obtained using a 20 MHz single element immersion transducer and the echo signals measured from bull’s eye tissue samples separated by approximately 4, 6, 8, and 10 cm diagonally and 2 cm vertically from the fisheye lens. The experimental results demonstrate that the echo signal amplitudes, their center frequencies, and the −6 dB bandwidths obtained using red, green, and blue lights and a fisheye lens are acceptable when the fisheye lens is separated from a sample both diagonally and vertically. Therefore, fisheye-lens-based PA systems could be a potential method of achieving wide fields of view while reducing the mechanical motor effects.

  9. The analysis of optical wave beams propagation in lens systems

    Science.gov (United States)

    Kazakov, I.; Mosentsov, S.; Moskaletz, O.

    2016-08-01

    In this paper some aspects of the formation and propagation of optical wave beams in lens systems were considered. As an example, the two-lens optical information processing system was considered. Analysis of the two-lens optical circuit has been made with a systems approach perspective. As part of the radio-optical analogies had been applied certain provisions of the theory of dynamical systems to the spatial optical system. The lens system is represented as a simple series-connected optical elements with known spatial impulse response. General impulse response of such a system has been received, as well as consider some special cases of the impulse response. The question of the relationship between the parameters and the size of the input aperture lenses for undistorted transmission of the optical signal has been considered. Analysis of the energy loss resulting from the finite aperture of the lens. It's based on an assessment of the fraction of radiation that propagates beyond the lens. Analysis showed that the energy losses depend explicitly on the following parameters: radiation wavelength, distance between input aperture and lens, and ratio of the input aperture and lens aperture. With the computer help simulation the dependence of losses was shown on the above parameters

  10. Why are there so many system shapes in lens design?

    NARCIS (Netherlands)

    Bociort, F.

    2010-01-01

    The presence of many local minima in the merit function landscape is perhaps the most difficult challenge in lens design. We present a simplified mathematical model that illustrates why the number of local minima increases rapidly with each additional lens added to the imaging system. Comparisons

  11. Fractional Fourier transforms, symmetrical lens systems, and their cardinal planes.

    Science.gov (United States)

    Moreno, Ignacio; Sánchez-López, María M; Ferreira, Carlos; Mateos, Felipe

    2007-07-01

    We study the relation between optical lens systems that perform a fractional Fourier transform (FRFT) with the geometrical cardinal planes. We demonstrate that lens systems symmetrical with respect to the central plane provide an exact FRFT link between the input and output planes. Moreover, we show that the fractional order of the transform has real values between 0 and 2 when light propagation is produced between principal planes and antiprincipal planes, respectively. Finally, we use this new point of view to design an optical lens system that provides FRFTs with variable fractional order in the range (0,2) without moving the input and output planes.

  12. High Dk piggyback contact lens system for contact lens-intolerant keratoconus patients.

    Science.gov (United States)

    Sengor, Tomris; Kurna, Sevda Aydin; Aki, Suat; Ozkurt, Yelda

    2011-01-01

    The aim of the study was to examine the clinical success of high Dk (oxygen permeability) piggyback contact lens (PBCL) systems for the correction of contact lens intolerant keratoconus patients. Sixteen patients (29 eyes) who were not able to wear gas-permeable rigid lenses were included in this study. Hyper Dk silicone hydrogel (oxygen transmissibility or Dk/t = 150 units) and fluorosilicone methacrylate copolymer (Dk/t = 100 units) lenses were chosen as the PBCL systems. The clinical examinations included visual acuity and corneal observation by biomicroscopy, keratometer reading, and fluorescein staining before and after fitting the PBCL system. INDICATIONS FOR USING PBCL SYSTEM WERE: lens stabilization and comfort, improving comfort, and adding protection to the cone. Visual acuities increased significantly in all of the patients compared with spectacles (P = 0). Improvement in visual acuity compared with rigid lenses alone was recorded in 89.7% of eyes and no alteration of the visual acuity was observed in 10.3% of the eyes. Wearing time of PBCL systems for most of the patients was limited time (mean 6 months, range 3-12 months); thereafter they tolerated rigid lenses alone except for 2 patients. The PBCL system is a safe and effective method to provide centering and corneal protection against mechanical trauma by the rigid lenses for keratoconus patients and may increase contact lens tolerance.

  13. Lens-coupled x-ray imaging systems

    Science.gov (United States)

    Fan, Helen Xiang

    Digital radiography systems are important diagnostic tools for modern medicine. The images are produced when x-ray sensitive materials are coupled directly onto the sensing element of the detector panels. As a result, the size of the detector panels is the same size as the x-ray image. An alternative to the modern DR system is to image the x-ray phosphor screen with a lens onto a digital camera. Potential advantages of this approach include rapid readout, flexible magnification and field of view depending on applications. We have evaluated lens-coupled DR systems for the task of signal detection by analyzing the covariance matrix of the images for three cases, using a perfect detector and lens, when images are affected by blurring due to the lens and screen, and for a signal embedded in a complex random background. We compared the performance of lens-coupled DR systems using three types of digital cameras. These include a scientific CCD, a scientific CMOS, and a prosumer DSLR camera. We found that both the prosumer DSLR and the scientific CMOS have lower noise than the scientific CCD camera by looking at their noise power spectrum. We have built two portable low-cost DR systems, which were used in the field in Nepal and Utah. We have also constructed a lens-coupled CT system, which included a calibration routine and an iterative reconstruction algorithm written in CUDA.

  14. High Dk piggyback contact lens system for contact lens-intolerant keratoconus patients

    Directory of Open Access Journals (Sweden)

    Tomris Sengor

    2011-03-01

    Full Text Available Tomris Sengor, Sevda Aydin Kurna, Suat Aki, Yelda ÖzkurtFatih Sultan Mehmet Training and Research Hospital, Istanbul, TurkeyBackground: The aim of the study was to examine the clinical success of high Dk (oxygen permeability piggyback contact lens (PBCL systems for the correction of contact lens intolerant keratoconus patients.Methods: Sixteen patients (29 eyes who were not able to wear gas-permeable rigid lenses were included in this study. Hyper Dk silicone hydrogel (oxygen transmissibility or Dk/t = 150 units and fluorosilicone methacrylate copolymer (Dk/t = 100 units lenses were chosen as the PBCL systems. The clinical examinations included visual acuity and corneal observation by biomicroscopy, keratometer reading, and fluorescein staining before and after fitting the PBCL system.Results: Indications for using PBCL system were: lens stabilization and comfort, improving comfort, and adding protection to the cone. Visual acuities increased significantly in all of the patients compared with spectacles (P = 0. Improvement in visual acuity compared with rigid lenses alone was recorded in 89.7% of eyes and no alteration of the visual acuity was observed in 10.3% of the eyes. Wearing time of PBCL systems for most of the patients was limited time (mean 6 months, range 3–12 months; thereafter they tolerated rigid lenses alone except for 2 patients.Conclusion: The PBCL system is a safe and effective method to provide centering and corneal protection against mechanical trauma by the rigid lenses for keratoconus patients and may increase contact lens tolerance.Keywords: piggyback contact lens, keratoconus, irregular astigmatism

  15. Practical assessment of veiling glare in camera lens system

    OpenAIRE

    Ivana Tomić; Igor Karlović; Ivana Jurič

    2014-01-01

    Veiling glare can be defined as an unwanted or stray light in an optical system caused by internal reflections between elements of the camera lens. It leads to image fogging and degradation of both image density and contrast, diminishing its overall quality. Each lens is susceptible to veiling glare to some extent - sometimes it is negligible, but it most cases it leads to the visible defects in an image. Unlike the other flaws and errors, lens flare is not easy to correct. Hence, it is highl...

  16. Self retaining contact lens system for vitreous surgery

    Directory of Open Access Journals (Sweden)

    Chalam Kakarla

    2004-01-01

    Full Text Available We describe the principle and design of a new self-retaining contact lens system for vitreous surgery. The system has three lenses: the plano-concave, prism and magnifying lens. This system is based on the principle of a direct imaging contact lens, designed for a 150-200mm focal length operating microscope. The contact lenses are designed to have an inferior concave surface [radius of curvature (ROC 7.7mm], modified by the addition of four footplates to provide stability and centration during vitreous surgery. The lenses are used with a drop of viscoelastic material placed between the concave surface of the contact lens and cornea. This induces negative suction and helps retain the lens in position during surgery. These specially designed lenses provide a stable, well-centered, high-resolution, magnified view of the fundus. This system eliminates the need for a skilled assistant or for suturing the lens to the sclera during vitreous surgery.

  17. Daylighting System Based on Novel Design of Linear Fresnel lens

    Directory of Open Access Journals (Sweden)

    Thanh Tuan Pham

    2017-10-01

    Full Text Available In this paper, we present a design and optical simulation of a daylighting system using a novel design of linear Fresnel lens, which is constructed based on the conservation of optical path length and edge ray theorem. The linear Fresnel lens can achieve a high uniformity by using a new idea of design in which each groove of the lens distributes sunlight uniformly over the receiver so that the whole lens also uniformly distributes sunlight over the receiver. In this daylighting system, the novel design of linear Fresnel lens significantly improves the uniformity of collector and distributor. Therefore, it can help to improve the performance of the daylighting system. The structure of the linear Fresnel lenses is designed by using Matlab. Then, the structure of lenses is appreciated by ray tracing in LightToolsTM to find out the optimum lens shape. In addition, the simulation is performed by using LightToolsTM to estimate the efficiency of the daylighting system. The results show that the designed collector can achieve the efficiency of ~80% with the tolerance of ~0.60 and the concentration ratio of 340 times, while the designed distributor can reach a high uniformity of >90%.

  18. 1600+434 - A NEW GRAVITATIONAL LENS SYSTEM

    NARCIS (Netherlands)

    JACKSON, N; DEBRUYN, AG; MYERS, S; BREMER, MN; MILEY, GK; SCHILIZZI, RT; BROWNE, IWA; NAIR, S; WILKINSON, PN; BLANDFORD, RD; PEARSON, TJ; READHEAD, ACS

    1995-01-01

    We report the discovery of a new gravitational lens system associated with the flat-spectrum radio source 1600+434. The system has been found in a new large survey of such radio sources. It consists of a 1.4-arcsec double radio source with an associated optical double at the same position and

  19. Intraocular camera for retinal prostheses: Refractive and diffractive lens systems

    Science.gov (United States)

    Hauer, Michelle Christine

    The focus of this thesis is on the design and analysis of refractive, diffractive, and hybrid refractive/diffractive lens systems for a miniaturized camera that can be surgically implanted in the crystalline lens sac and is designed to work in conjunction with current and future generation retinal prostheses. The development of such an intraocular camera (IOC) would eliminate the need for an external head-mounted or eyeglass-mounted camera. Placing the camera inside the eye would allow subjects to use their natural eye movements for foveation (attention) instead of more cumbersome head tracking, would notably aid in personal navigation and mobility, and would also be significantly more psychologically appealing from the standpoint of personal appearances. The capability for accommodation with no moving parts or feedback control is incorporated by employing camera designs that exhibit nearly infinite depth of field. Such an ultracompact optical imaging system requires a unique combination of refractive and diffractive optical elements and relaxed system constraints derived from human psychophysics. This configuration necessitates an extremely compact, short focal-length lens system with an f-number close to unity. Initially, these constraints appear highly aggressive from an optical design perspective. However, after careful analysis of the unique imaging requirements of a camera intended to work in conjunction with the relatively low pixellation levels of a retinal microstimulator array, it becomes clear that such a design is not only feasible, but could possibly be implemented with a single lens system.

  20. Improved Vision and Contact Lens Wear Time With Piggy-Back Contact Lens Systems in Children After Penetrating Corneal Trauma.

    Science.gov (United States)

    Cromelin, Caroline; Russell, Buddy; Lambert, Scott R

    2017-07-01

    Consecutive case series of children treated successfully with "piggy-back" (PB) contact lens systems after corneal trauma. We reviewed the medical record of all children ages 4 to 14 years treated at the Emory Eye Center between January 11, 2003 and January 11, 2013 with PB contact lens systems. Four children with a history of corneal penetrating trauma were treated with a PB lens system, with a mean age of 7±0.08 (range: 6-8) years. Best-corrected spectacle vision was count fingers in two children and logMAR +0.70 (Snellen equivalent 20/100) and logMAR +0.6 (Snellen equivalent 20/80) in the remaining two. The PB lens system was introduced with a mean of 15.7±6.5 (range: 9-22) months after the injury. All patients were initially fitted with gas-permeable (GP) lenses. Each child achieved 11 or more hours of daily contact lens wear time in PB systems. The mean best-corrected logMAR visual acuity using the PB system was 0.26±0.21 (Snellen equivalent 20/36). The mean improvement in best-corrected logMAR between GP and PB lens systems was +0.21±0.11, which corresponds to an improvement of greater than two lines on the Snellen chart. Piggy-back contact lens systems can be helpful to improve vision and contact lens wearing time in children with irregular astigmatism after corneal trauma, who are intolerant of GP contact lenses.

  1. Task-based evaluation of practical lens designs for lens-coupled digital mammography systems

    Science.gov (United States)

    Chen, Liying; Foo, Leslie D.; Cortesi, Rebecca L.; Thompson, Kevin P.; Barrett, Harrison H.

    2007-03-01

    Recent developments in low-noise, large-area CCD detectors have renewed interest in radiographic systems that use a lens to couple light from a scintillation screen to a detector. The lenses for this application must have very large numerical apertures and high spatial resolution over a FOV. This paper expands on our earlier work by applying the principles of task-based assessment of image quality to development of meaningful figures of merit for the lenses. The task considered in this study is detection of a lesion in a mammogram, and the figure of merit used is the lesion detectability, expressed as a task-based signal-to-noise ratio (SNR), for a channelized Hotelling observer (CHO). As in the previous work, the statistical model accounts for the random structure in the breast, the statistical properties of the scintillation screen, the random coupling of light to the CCD, the detailed structure of the shift-variant lens point spread function (PSF), and Poisson noise of the X-ray flux. The lenses considered range from F/0.9 to F/1.2. All yield nominally the same spot size at a given field. Among the F/0.9 lenses, some of them were designed by conventional means for high resolution and some for high contrast, and the shapes of the PSF differ considerably. The results show that excessively large lens numerical apertures do not improve the task-based SNR but dramatically increase the optics fabrication cost. Contrary to common wisdom, high-contrast designs have higher task-based SNRs than high-resolution designs when the signal is small. Additionally, we constructed a merit function to successfully tune the lenses to perform equally well anywhere in the FOV.

  2. Practical assessment of veiling glare in camera lens system

    Directory of Open Access Journals (Sweden)

    Ivana Tomić

    2014-12-01

    Full Text Available Veiling glare can be defined as an unwanted or stray light in an optical system caused by internal reflections between elements of the camera lens. It leads to image fogging and degradation of both image density and contrast, diminishing its overall quality. Each lens is susceptible to veiling glare to some extent - sometimes it is negligible, but it most cases it leads to the visible defects in an image. Unlike the other flaws and errors, lens flare is not easy to correct. Hence, it is highly recommended to prevent it during the capturing phase, if possible. For some applications, it can also be useful to estimate the susceptibility to a lens glare i.e. the degree of a glare in the lens system. Few methods are usually used for this types of testing. Some of the methods are hard to implement and often do not lead to consistent results. In this paper, we assessed one relatively easy method for practical evaluation of veiling glare. Method contains three steps: creating an appropriate scene, capturing the target image and analyzing it. In order to evaluate its applicability, we tested four lenses for Nikon 700 digital camera. Lenses used were with the fixed focal length of 35 and 85 mm and differed by the coatings of their elements. Furthermore, we evaluated the influence of aperture on veiling glare value. It was shown that presented method is not applicable for testing the lenses with short focal length and that the new generation of lenses, equipped with Nano crystal coatings are less susceptible to veiling glare. Aperture did not affect veiling glare value significantly.

  3. An electro-active polymer based lens module for dynamically varying focal system

    Science.gov (United States)

    Yun, Sungryul; Park, Suntak; Nam, Saekwang; Park, Bongje; Park, Seung Koo; Mun, Seongcheol; Lim, Jeong Mook; Kyung, Ki-Uk

    2016-10-01

    We demonstrate a polymer-based active-lens module allowing a dynamic focus controllable optical system with a wide tunable range. The active-lens module is composed of parallelized two active-lenses with a convex and a concave shaped hemispherical lens structure, respectively. Under operation with dynamic input voltage signals, each active-lens produces translational movement bi-directionally responding to a hybrid driving force that is a combination of an electro-active response of a thin dielectric elastomer membrane and an electro-static attraction force. Since the proposed active lens module widely modulates a gap-distance between lens-elements, an optical system based on the active-lens module provides widely-variable focusing for selective imaging of objects in arbitrary position.

  4. Tolerance optimization of a mobile phone camera lens system.

    Science.gov (United States)

    Jung, Sangjin; Choi, Dong-Hoon; Choi, Byung-Lyul; Kim, Ju Ho

    2011-08-10

    In the manufacturing process for the lens system of a mobile phone camera, various types of assembly and manufacturing tolerances, such as tilt and decenter, should be appropriately allocated. Because these tolerances affect manufacturing cost and the expected optical performance, it is necessary to choose a systematic design methodology for determining optimal tolerances. In order to determine the tolerances that minimize production cost while satisfying the reliability constraints on important optical performance indices, we propose a tolerance design procedure for a lens system. A tolerance analysis is carried out using Latin hypercube sampling for evaluating the expected optical performance. The tolerance optimization is carried out using a function-based sequential approximate optimization technique that can reduce the computational burden and smooth numerical noise occurring in the optimization process. Using the proposed design approach, the optimal production cost was decreased by 28.3% compared to the initial cost while satisfying all the constraints on the expected optical performance. We believe that the tolerance analysis and design procedure presented in this study can be applied to the tolerance optimization of other systems.

  5. Bionic optical imaging system with aspheric solid-liquid mixed variable-focus lens

    Science.gov (United States)

    Du, Jia-Wei; Wang, Xuan-Yin; Liang, Dan

    2016-02-01

    A bionic optical imaging system with an aspheric solid-liquid mixed variable-focus lens was designed and fabricated. The entire system mainly consisted of a doublet lens, a solid-liquid mixed variable-focus lens, a connecting part, and a CCD imaging device. To mimic the structure of the crystalline lens, the solid-liquid mixed variable-focus lens consisted of a polydimethylsiloxane (PDMS) lens, a polymethyl methacrylate lens, and the liquid of ethyl silicone oil. By pumping liquid in or out of the cavity using a microinjector, the curvatures of the front and rear surfaces of the PDMS lens were varied, resulting in a change of focal length. The overall structure of the system was presented, as well as a detailed description of the solid-liquid mixed variable-focus lens, material, and fabrication process. Under different injection volumes, the deformation of the PDMS lens was measured and simulated, pictures were captured, and the optical performance was analyzed in simulations and experiments. The focal length of the system ranged from 25.05 to 14.61 mm, and the variation of the diopter was 28.5D, which was larger than that of the human eye.

  6. Manufacturing PDMS micro lens array using spin coating under a multiphase system

    Science.gov (United States)

    Sun, Rongrong; Yang, Hanry; Rock, D. Mitchell; Danaei, Roozbeh; Panat, Rahul; Kessler, Michael R.; Li, Lei

    2017-05-01

    The development of micro lens arrays has garnered much interest due to increased demand of miniaturized systems. Traditional methods for manufacturing micro lens arrays have several shortcomings. For example, they require expensive facilities and long lead time, and traditional lens materials (i.e. glass) are typically heavy, costly and difficult to manufacture. In this paper, we explore a method for manufacturing a polydimethylsiloxane (PDMS) micro lens array using a simple spin coating technique. The micro lens array, formed under an interfacial tension dominated system, and the influence of material properties and process parameters on the fabricated lens shape are examined. The lenses fabricated using this method show comparable optical properties—including surface finish and image quality—with a reduced cost and manufacturing lead time.

  7. A panoramic imaging system based on fish-eye lens

    Science.gov (United States)

    Wang, Ye; Hao, Chenyang

    2017-10-01

    Panoramic imaging has been closely watched as one of the major technologies of AR and VR. Mainstream panoramic imaging techniques lenses include fish-eye lenses, image splicing, and catadioptric imaging system. Meanwhile, fish-eyes are widely used in the big picture video surveillance. The advantage of fish-eye lenses is that they are easy to operate and cost less, but how to solve the image distortion of fish-eye lenses has always been a very important topic. In this paper, the image calibration algorithm of fish-eye lens is studied by comparing the method of interpolation, bilinear interpolation and double three interpolation, which are used to optimize the images.

  8. Efficacy of Lens Protection Systems: Dependency on Different Cranial CT Scans in The Acute Stroke Setting.

    Science.gov (United States)

    Guberina, Nika; Forsting, Michael; Ringelstein, Adrian

    2017-06-15

    To evaluate the dose-reduction potential with different lens protectors for patients undergoing cranial computed tomography (CT) scans. Eye lens dose was assessed in vitro (α-Al2O3:C thermoluminescence dosemeters) using an Alderson-Rando phantom® in cranial CT protocols at different CT scanners (SOMATOM-Definition-AS+®(CT1) and SOMATOM-Definition-Flash® (CT2)) using two different lens-protection systems (Somatex® (SOM) and Medical Imaging Systems® (MIS)). Summarised percentage of the transmitted photons: (1) CT1 (a) unenhanced CT (nCT) with gantry angulation: SOM = 103%, MIS = 111%; (2) CT2 (a) nCT without gantry angulation: SOM = 81%, MIS = 91%; (b) CT angiography (CTA) with automatic dose-modulation technique: SOM = 39%, MIS = 74%; (c) CTA without dose-modulation technique: SOM = 22%, MIS = 48%; (d) CT perfusion: SOM = 44%, MIS = 69%. SOM showed a higher dose-reduction potential than MIS maintaining equal image quality. Lens-protection systems are most effective in CTA protocols without dose-reduction techniques. Lens-protection systems lower the average eye lens dose during CT scans up to 1/3 (MIS) and 2/3 (SOM), respectively, if the eye lens is exposed to the direct beam of radiation. Considering both the CT protocol and the material of lens protectors, they seem to be mandatory for reducing the radiation exposure of the eye lens. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Development of an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Koki; Oka, Miki; Yamamoto, Seiichi

    2017-02-01

    We developed an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube (PSPMT). The alpha-particle imaging system consists of an optical lens, an extension tube and a 1 in. square high quantum efficiency (HQE) type PSPMT. After a ZnS(Ag) is attached to subject, the scintillation image of ZnS(Ag) is focused on the photocathode of the PSPMT by the use of the optical lens. With this configuration we could image the alpha particle distribution with energy information without contacting to the subject. The spatial resolution and energy resolution were ~0.8 mm FWHM and 50% FWHM at 5 mm from the optical lens, respectively. We could successfully image the alpha particle distribution in uranium ore. The developed alpha-particle imaging system will be a new tool for imaging alpha emitters with energy information without contacting the subject.

  10. Development of an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube

    Science.gov (United States)

    Ando, Koki; Oka, Miki; Yamamoto, Seiichi

    2017-02-01

    We developed an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube (PSPMT). The alpha-particle imaging system consists of an optical lens, an extension tube and a 1 in. square high quantum efficiency (HQE) type PSPMT. After a ZnS(Ag) is attached to subject, the scintillation image of ZnS(Ag) is focused on the photocathode of the PSPMT by the use of the optical lens. With this configuration we could image the alpha particle distribution with energy information without contacting to the subject. The spatial resolution and energy resolution were 0.8 mm FWHM and 50% FWHM at 5 mm from the optical lens, respectively. We could successfully image the alpha particle distribution in uranium ore. The developed alpha-particle imaging system will be a new tool for imaging alpha emitters with energy information without contacting the subject.

  11. Symmetrical optical imaging system with bionic variable-focus lens for off-axis aberration correction

    Science.gov (United States)

    Wang, Xuan-Yin; Du, Jia-Wei; Zhu, Shi-Qiang

    2017-09-01

    A bionic variable-focus lens with symmetrical layered structure was designed to mimic the crystalline lens. An optical imaging system based on this lens and with a symmetrical structure that mimics the human eye structure was proposed. The refractive index of the bionic variable-focus lens increases from outside to inside. The two PDMS lenses with a certain thickness were designed to improve the optical performance of the optical imaging system and minimise the gravity effect of liquid. The paper presents the overall structure of the optical imaging system and the detailed description of the bionic variable-focus lens. By pumping liquid in or out of the cavity, the surface curvatures of the rear PDMS lens were varied, resulting in a change in the focal length. The focal length range of the optical imaging system was 20.71-24.87 mm. The optical performance of the optical imaging system was evaluated by imaging experiments and analysed by ray tracing simulations. On the basis of test and simulation results, the optical performance of the system was quite satisfactory. Off-axis aberrations were well corrected, and the image quality was greatly improved.

  12. Constraints on long-lived electrically charged massive particles from anomalous strong lens systems

    Science.gov (United States)

    Kamada, Ayuki; Inoue, Kaiki Taro; Kohri, Kazunori; Takahashi, Tomo

    2017-11-01

    We investigate anomalous strong lens systems, particularly weak lens effects of structures in the line of sight, in models with long-lived electrically charged massive particles (CHAMPs). In such models, matter density perturbations are suppressed through the acoustic damping and the flux ratios in lens systems are impacted, from which we can constrain the nature of CHAMPs. For this purpose, we perform N-body simulations and develop a fitting formula to obtain non-linear matter power spectra in models where cold neutral dark matter and CHAMPs coexist in the early Universe. By using the observed anomalous quadruple lens samples, we obtained the constraints on the lifetime (τCh) and the mass density fraction (rCh) of CHAMPs. We show that, for rCh=1, the lifetime is bounded as τCh models are also discussed.

  13. Computerized method and system for designing an aerodynamic focusing lens stack

    Science.gov (United States)

    Gard, Eric [San Francisco, CA; Riot, Vincent [Oakland, CA; Coffee, Keith [Diablo Grande, CA; Woods, Bruce [Livermore, CA; Tobias, Herbert [Kensington, CA; Birch, Jim [Albany, CA; Weisgraber, Todd [Brentwood, CA

    2011-11-22

    A computerized method and system for designing an aerodynamic focusing lens stack, using input from a designer related to, for example, particle size range to be considered, characteristics of the gas to be flowed through the system, the upstream temperature and pressure at the top of a first focusing lens, the flow rate through the aerodynamic focusing lens stack equivalent at atmosphere pressure; and a Stokes number range. Based on the design parameters, the method and system determines the total number of focusing lenses and their respective orifice diameters required to focus the particle size range to be considered, by first calculating for the orifice diameter of the first focusing lens in the Stokes formula, and then using that value to determine, in iterative fashion, intermediate flow values which are themselves used to determine the orifice diameters of each succeeding focusing lens in the stack design, with the results being output to a designer. In addition, the Reynolds numbers associated with each focusing lens as well as exit nozzle size may also be determined to enhance the stack design.

  14. Single-stage quintuplet for upgrading triplet based lens system: Simulation for Atomki microprobe

    Science.gov (United States)

    Ponomarov, Artem; Rajta, Istvan; Nagy, Gyula; Romanenko, Oleksandr V.

    2017-08-01

    Among different configurations of lens systems for nuclear microprobes, the most common one is a triplet of magnetic quadrupole lenses. Nowadays, microanalysis and material modification will undoubtedly benefit from an improvement in spatial resolution. This work presents the results of simulations for improvement of the Oxford Triplet lens system at the Atomki microprobe with consideration of its system parameters and measured beam brightness distribution. For this purpose, an additional single-unit doublet of lenses with two power supplies was introduced. Using earlier developed methods, such a quintuplet system was optimized in order to determine the parameters which provided the highest resolution for different current operational modes with the same microprobe geometry. The tolerances for lens positioning accuracy were also calculated. The obtained quintuplet parameters indicate a resolution improvement for the Atomki microprobe compared to the Oxford Triplet system and these results validate further experimental testing of the proposed quintuplet.

  15. Development of a triplet magnetic lens system to focus a pulsed neutron beam

    Energy Technology Data Exchange (ETDEWEB)

    Oku, Takayuki; Kira, Hiroshi; Shinohara, Takenao; Takata, Shin-ichi; Arai, Masatoshi; Suzuki, Jun-ichi; Shimizu, Hirohiko M, E-mail: oku.takayuki@jaea.go.jp

    2010-11-01

    A triplet magnetic lens system composed of three sextupole-magnets and two spin flippers was constructed to focus pulsed neutrons in a wide wavelength range with same focal lengths. In this study, we performed a pulsed neutron beam focusing experiment with the system. The design of the system and the experimental results are shown and discussed.

  16. Estimation of clearances in the design and adjustment of barrel type lens systems

    Science.gov (United States)

    Beloivan, P. A.; Latyev, S. M.; Frolov, D. N.; Theska, R.

    2017-06-01

    Estimation of probable clearances in the fit of the installed lenses and the impact from mounting and adjustment of units on system alignment and the resulting imaging quality has been considered. The characters of dispersion fields and acceptable deviations in mating dimensions of parts and their allowance have been analyzed for the estimation of probable clearances. Very commonly existing deviations in the clearances have a considerable systematic component due to systematic components of errors in the mated dimensions of parts. It has been shown that the assembly of lens based optical systems in horizontal position of its body allows vast reduction of the impact given by clearances on the accuracy of the alignment of the lens parts as compared to assembly in vertical position of its body, as in the this case the lens misalignment is due to errors in the diameters of lens components. For the adjustment of the quality of the image generated by the optical system it is necessary to take into account both the impact from misalignment of lens components on edge and central aberrations of the image field.

  17. An RFID-based on-lens sensor system for long-term IOP monitoring.

    Science.gov (United States)

    Hsu, Shun-Hsi; Chiou, Jin-Chern; Liao, Yu-Te; Yang, Tzu-Sen; Kuei, Cheng-Kai; Wu, Tsung-Wei; Huang, Yu-Chieh

    2015-01-01

    In this paper, an RFID-based on-lens sensor system is proposed for noninvasive long-term intraocular pressure monitoring. The proposed sensor IC, fabricated in a 0.18um CMOS process, consists of capacitive sensor readout circuitry, RFID communication circuits, and digital processing units. The sensor IC is integrated with electroplating capacitive sensors and a receiving antenna on the contact lens. The sensor IC can be wirelessly powered, communicate with RFID compatible equipment, and perform IOP measurement using on-lens capacitive sensor continuously from a 2cm distance while the incident power from an RFID reader is 20 dBm. The proposed system is compatible to Gen2 RFID protocol, extending the flexibility and reducing the self-developed firmware efforts.

  18. The role of luminous substructure in the gravitational lens system MG 2016+112

    NARCIS (Netherlands)

    More, A.; McKean, J. P.; More, S.; Porcas, R. W.; Koopmans, L. V. E.; Garrett, M. A.

    2009-01-01

    MG 2016+112 is a quadruply imaged lens system with two complete images A and B and a pair of merging partial images in region C as seen in the radio. The merging images are found to violate the expected mirror symmetry. This indicates an astrometric anomaly which could only be of gravitational

  19. Student Satisfaction with Learning Management Systems: A Lens of Critical Success Factors

    Science.gov (United States)

    Naveh, Gali; Tubin, Dorit; Pliskin, Nava

    2012-01-01

    Institutions of higher education have invested heavily in learning management systems (LMS) for creating course websites. Yet, how to assess LMS effectiveness is not fully agreed upon. Based on institutional theory, this article considers student satisfaction as indicative of LMS success and proposes a lens of critical success factors (CSF) as a…

  20. The use of contact lens telescopic systems in low vision rehabilitation.

    Science.gov (United States)

    Vincent, Stephen J

    2017-06-01

    Refracting telescopes are afocal compound optical systems consisting of two lenses that produce an apparent magnification of the retinal image. They are routinely used in visual rehabilitation in the form of monocular or binocular hand held low vision aids, and head or spectacle-mounted devices to improve distance visual acuity, and with slight modifications, to enhance acuity for near and intermediate tasks. Since the advent of ground glass haptic lenses in the 1930's, contact lenses have been employed as a useful refracting element of telescopic systems; primarily as a mobile ocular lens (the eyepiece), that moves with the eye. Telescopes which incorporate a contact lens eyepiece significantly improve the weight, comesis, and field of view compared to traditional spectacle-mounted telescopes, in addition to potential related psycho-social benefits. This review summarises the underlying optics and use of contact lenses to provide telescopic magnification from the era of Descartes, to Dallos, and the present day. The limitations and clinical challenges associated with such devices are discussed, along with the potential future use of reflecting telescopes incorporated within scleral lenses and tactile contact lens systems in low vision rehabilitation. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  1. Overview of contact lens postmarket surveillance in the United States: system and recent study results.

    Science.gov (United States)

    Chalmers, Robin L; Gleason, William

    2013-01-01

    This is an overview of the US contact lens (CL) postmarket surveillance systems and surveillance study results that include silicone hydrogel CLs. As 30-night continuous wear silicone hydrogel and rigid gas-permeable (RGP) CLs were approved for use in the United States in 2001, the Food and Drug Administration (FDA) mandated large postmarket surveillance studies to assess the risk of microbial keratitis with those products when worn with the 30-night wearing schedule. Since the time of the approvals, RGP 30-night wear has been used sparingly and a shift from 30-night wear has occurred for silicone hydrogel lenses. Several silicone hydrogel lenses have been approved and most of these lenses are being prescribed for daily or flexible wear and not for 30-night wear. With daily wear and less overnight use, silicone hydrogel lenses are regularly exposed to lens care products, lens cases, and improper handling, all of which may introduce sources of microbial contamination that could trigger lens-related complications. This summary of CL postmarket surveillance system and methods gives results of FDA-mandated surveillance and of recent US studies that observed "real-world" populations for safety results outside the bounds of highly controlled prospective clinical trials.

  2. Elements of a gravitational lens system assuming an elliptical galaxy model

    Science.gov (United States)

    Molina, U. E.; Viloria, P.; Steffanell, I.

    2017-10-01

    This work studies some elements of gravitational lensing by galaxies such as the lens equation, deflection angle, lensing potential and time delay, modeling the mass distribution of the lensing galaxy as an elliptical galaxy. The mass distribution function ρ of the deflecting galaxy indicates that it has a nucleus with radius a in its core, a free-form parameter b (b>a), and that the mass density of the nucleus is ρ0. The mass density distribution ρ allows us to find the surface mass density Σ (projected on the plane of the lens), followed by general elements of the gravitational lens expressed in terms of the geometric parameters a and b. The relation between these parameters is defined by the adimensional factor n=b/a>1. The results of this work can be applied to any galactic lens system to conduct an analysis based on the temporal delay between two images and to determine the conditions that must be satisfied by the parameter n.

  3. Non-Linear Beam Transport System for the LENS 7 MeV Proton Beam

    CERN Document Server

    Jones, William P; Derenchuk, Vladimir Peter; Rinckel, Thomas; Solberg, Keith

    2005-01-01

    A beam transport system has been designed to carry a high-intensity low-emittance proton beam from the exit of the RFQ-DTL acceleration system of the Indiana University Low Energy Neutron System (LENS)* to the neutron production target. The goal of the design was to provide a beam of uniform density over a 3cm by 3cm area at the target. Two octupole magnets** are employed in the beam line to provide the necessary beam phase space manipulations to achieve this goal. First order calculations were done using TRANSPORT and second order calculations have been performed using TURTLE. Second order simulations have been done using both a Gaussian beam distribution and a particle set generated by calculations of beam transport through the RFQ-DTL using PARMILA. Comparison of the design characteristics with initial measurements from the LENS commissioning process will be made.

  4. Corneo-scleral contact lens in a piggyback system for keratoconus: A case report.

    Science.gov (United States)

    Porcar, Esteban; Montalt, Juan Carlos; España-Gregori, Enrique; Peris-Martínez, Cristina

    2017-06-01

    We describe a case of fitting a corneo-scleral contact lens with a multi-aspheric geometry design (MAGD CScL) on top of a daily silicone hydrogel lens (piggyback system) for keratoconus management. A 48-year-old man using soft toric contact lenses required an improvement in the unsatisfactory quality of his vision. He presented with bilateral asymmetric keratoconus with high myopia in the right eye (RE) and severe myopia in the left eye (LE). In addition, he had low vision in his LE because of a maculopathy. He was fitted with MAGD CScL to correct his irregular astigmatism. A diagnostic trial set was used in the fitting process and the patient was assessed according to a standardised fitting methodology. Visual acuity, corneal topography and contrast sensitivity were evaluated. The follow-up period was 1year. The best spectacle-corrected visual acuity was 0.5 logMAR for the RE with -10 D/-5 D×60° and 2 logMAR for the LE with -20 D/-3 D×105°. After fitting MAGD CScL, visual acuity improved significantly to 0.1 logMAR for the RE and 1.3 logMAR for the LE, as well as contrast sensitivity. The fitting parameters of the base curve, diameter, and power were 7.05mm, 12.60mm, -18.50 D and 7.15mm, 12.60mm, -19 D for the RE and LE, respectively. Optimal fitting characteristics were found in terms of lens position and lens movement. To increase the time of MAGD CScL wear, they piggybacked on daily silicone hydrogel lenses of low power (-0.5 D). The patient reported being comfortable with this piggyback system for approximately 15h a day. After 1year of using the piggyback system, visual quality and wearing time were maintained. In addition, no adverse ocular effects were found during this period. This case report shows that in this patient a MAGD CScL could be fitted successfully on a daily silicone hydrogel lens in a piggyback system for keratoconus management, providing good visual quality along with prolonged use times and without adverse effects on the cornea

  5. Conceptualizing HRM system strength through a cross-cultural lens

    NARCIS (Netherlands)

    Farndale, E.; Sanders, K.

    2017-01-01

    To date, literature on HRM system strength has been largely universalistic, that is, it has not considered the implications of context. This is problematic as it overlooks a more detailed exploration of the outcomes of HRM system strength in different situational settings. Adopting a contingency

  6. Compensation of optical system distortion and image perspective deformations for the projection lens

    Science.gov (United States)

    Burtseva, Anastasiia A.; Ezhova, Kseniia V.; Trifanov, Oleg V.

    2017-06-01

    In the article takes up the possibility of optical system distortion compensation for projection lens by making predistortions into projected digital image. Image processing is producing for main types of optical system distortion, which can be described both as power polynomial and as Zernike polynomials. Special attention is given for perspective deformations which arise in the deviation of the optical axis from perpendicular to the plane of projection. In processing takes into account both as horizontal and as vertical perspective deformation. For possibility of optical system distortion compensation there is a need to provisional certification of lens by Abbe grid for taking polynomial description of distortion. According to certification results performed image processing on the points corresponding to the nodes of the grid Abbe. As a result of processing a digital image deformations introduced, the reverse occurring when deformations are projecting. Pre-made image deformations allow to compensate for distortion of optical system and the perspective deformation caused by the projection lens used, therefore, when projecting the image will largely corresponds to the original image. The results of the work is planning to use in the preparation of digital image mapping show, namely the projection on objects of complex geometric shapes.

  7. A wide-FoV athermalized infrared imaging system with a two-element lens

    Science.gov (United States)

    Feng, Bin; Shi, Zelin; Zhao, Yaohong; Liu, Haizheng; Liu, Li

    2017-12-01

    For infrared imaging systems to achieve wide field of view (FoV), wide operating temperature and low weight, this work designs a wide-FoV athermalized infrared imaging system (AIIS) with a two-element lens. Its principle, design, manufacture, measurement and performance validation are successively discussed. The two-element lens contains four surfaces, where three aspheric surfaces are introduced to reduce optical off-axis aberrations and a cubic surface is introduced to achieve athermalization. The key coding mask containing an aspheric surface and a cubic surface is manufactured by nano-metric machining of ion implanted material (NiIM). Experimental results validate that our wide-FoV wavefront coding AIIS has a full FoV of 26.10° and an operating temperature over -20 °C to +70 °C.

  8. Frequency Invariant Beam Steering for Short-Pulse Systems with a Rotman Lens

    Directory of Open Access Journals (Sweden)

    Andreas Lambrecht

    2010-01-01

    Full Text Available A promising approach for beam steering of high-voltage transient signals for HPEM-systems (High Power Electro Magnetic is presented. The inherent capability of the Rotman lens to provide true time delays is used to develop a prototype beam steering device for an antielectronics HPEM system in the frequency range from 350 MHz to 5 GHz. Results of analytical calculations, simulations, and measurements from a hardware prototype are presented. The detailed mechanical setup of the Rotman lens is presented. Additionally the output pulses are investigated when inputting a Gaussian-like transient signal. Then time domain measures of quality (full width at half maximum, ringing, delay spread, maximum of transfer function are investigated for these output transients, and the simulation and measurement results are compared. A concluding analysis of the realizable time domain array pattern shows the radiated pulse form.

  9. Vergleich kollegialer Einzel- mit Gruppen-Reviews allgemeinmedizinischer Multiple-Choice-Fragen [Comparison of Collegial Individual and Group Reviews of General Practice Multiple Choice Questions

    Directory of Open Access Journals (Sweden)

    Böhme, Klaus

    2012-08-01

    Full Text Available [english] Aims: In most German medical faculties, credits in general practice can be earned via exams using multiple-choice questions (MCQ. Measures such as peer-reviews may help assure the quality of these exams. In order to use time and personnel intensive peer reviews effectively and efficiently, the procedures used are key. Therefore, we wanted to find out whether there are differences between group and individual reviews regarding defined parameters.Methods: We conducted a controlled cross-over study with three GP reviewers from four different German universities. Each reviewed 80 MCQs, 40 individually and 40 within a group, including external assessments by a panel of experts. Furthermore all reviewers were asked to evaluate the review process and the time spent carrying out these reviews.Outcomes: We found no significant differences between the reliability and the validity of individual reviews versus group reviews. On average slightly more time was spent on group reviews compared with the individual reviews. The subjective assessments of the study participants regarding their satisfaction with the process and the efficiency and effectiveness of the reviews suggest a preference for group reviews.Conclusions: Based on this study, there are no definite recommendations for or against either approach. When choosing between the two, the specific work structures and organisation at the local faculty should be taken into account.[german] Zielsetzung: Im Fach Allgemeinmedizin werden die obligat zu benotenden Leistungsnachweise an vielen Hochschulstandorten über Klausuren mit Multiple-Choice-Fragen (MCF erbracht. Zur Qualitätssicherung bietet sich u.a. ein Peer-Review-Verfahren der eingesetzten MCF an. Für die optimale Effektivität und Effizienz solcher zeit- und personalintensiven Peer-Reviews ist nicht zuletzt die Verfahrensweise von Bedeutung. Ziel der Studie war es zu untersuchen, ob sich Einzel- von Gruppen-Reviews hinsichtlich

  10. A heterologous expression system for bovine lens transmembrane main intrinsic protein (MIP) in Nicotiana tabacum plants

    OpenAIRE

    de Peyer, O. S.; Wetten, Andrew C.; Dunwell, Jim M.; Crabbe, M.J.C.

    1999-01-01

    We have developed a heterologous expression system for transmembrane lens main intrinsic protein (MIP) in Nicotiana tabacum plant tissue. A native bovine MIP26 amplicon was subcloned into an expression cassette under the control of a constitutive Cauliflower Mosaic Virus promoter, also containing a neomycin phosphotransferase operon. This cassette was transformed into Agrobacterium tumefaciens by triparental mating and used to infect plant tissue grown in culture. Recombinant plants were sele...

  11. Investigation of a metamaterial slab lens and an imaging system based on an ellipsoidal cavity.

    Science.gov (United States)

    Kordi, Mahdi; Mirsalehi, Mir Mojtaba

    2017-06-01

    A slab metamaterial lens with a refractive index of -1 is capable of producing a perfect image, since it transfers all the plane waves from the object plane to the image plane without creating any distortion in their amplitudes and phases. However, its practical implementation encounters several challenges. In this paper, a lossless slab metamaterial lens is investigated using the ray-tracing technique. We also discuss propagating waves and evanescent waves and investigate an imaging system based on an ellipsoidal cavity. It is shown that since an ellipsoidal cavity transfers the beams from one of its foci to the other with the same amplitude and phase, it acts similarly to a metamaterial slab lens of n=-1. Therefore, this structure can be used as a subwavelength resolution imaging system. Also, it does not suffer from chromatic aberration, since all the rays transmitted from one focus pass through the other independent of the wavelength. Another important advantage of this system, compared to metamaterial-based superlenses, is that it can operate at any frequency as long as the dimensions of the cavity are much larger than the wavelength.

  12. TWO-LENS AFOCAL COMPENSATOR FOR THERMAL DEFOCUS CORRECTION OF CATADIOPTRIC SYSTEM

    Directory of Open Access Journals (Sweden)

    Stepan E. Ivanov

    2017-05-01

    Full Text Available Subject of Research. Traditionally, afocal compensators, located in parallel or in converging beams, are used to correct the aberrations of mirror systems. The additional property of afocality gives the possibility to ignore practically the selection of materials in the design, since, in this case, the achromatic correction is achieved automatically. A change in the ambient temperature leads to a change in the shape of the mirrors and their mutual arrangement, in addition, the optical characteristics of the compensator material change that leads to defocusing. Main Results. Based on the analysis of paraxial formulas valid for the correction of chromatic aberrations and thermal defocusing, we have obtained formulas that enable to evaluate the characteristics of the materials necessary for passive athermalization, that is, to keep image quality when the ambient temperature changes without using a mechanical offset of the sensor. It is shown that in a two-lens compensator used to correct aberrations of two-mirror lens in a converging beam of rays, it is necessary to use a combination of optical glasses and polymer materials for passive athermalization. Practical Relevance. Based on the theoretical correlations obtained, a two-mirror system with an afocal compensator is calculated with a high image quality maintained over a wide temperature range. The use of obtained formulas in practice made it possible to demonstrate the possibility of creation of athermalized catadioptric lens involving combinations of conventional glasses with modern polymeric materials. The method presented is not universal, but it gives the possibility to select materials for calculating the afocal two-lens systems, compensating the thermal defocusing of the image without active correction methods (mechanical shifts.

  13. Design and development of a laminated Fresnel lens for point-focus PV systems. Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, R.C.

    1982-12-01

    A laminated glass-plastic lens parquet using injection molded point focus Fresnel lenses is described. The second phase of a program aimed at investigating the cost effectiveness of a glass-plastic concentrator lens assembly is reported. The first phase dealt with the development of a first generation lens design, the selection of the preferred glass coverplate and glass-to-lens adhesive and initial injection molding lens molding trials. The second phase has dealt with the development of an improved lens design, a full size parquet lamination process, and a second group of injection molding lens molding trials.

  14. Reducing aberration effect of Fourier transform lens by modifying Fourier spectrum of diffractive optical element in beam shaping optical system.

    Science.gov (United States)

    Zhang, Fang; Zhu, Jing; Song, Qiang; Yue, Weirui; Liu, Jingdan; Wang, Jian; Situ, Guohai; Huang, Huijie

    2015-10-20

    In general, Fourier transform lenses are considered as ideal in the design algorithms of diffractive optical elements (DOEs). However, the inherent aberrations of a real Fourier transform lens disturb the far field pattern. The difference between the generated pattern and the expected design will impact the system performance. Therefore, a method for modifying the Fourier spectrum of DOEs without introducing other optical elements to reduce the aberration effect of the Fourier transform lens is proposed. By applying this method, beam shaping performance is improved markedly for the optical system with a real Fourier transform lens. The experiments carried out with a commercial Fourier transform lens give evidence for this method. The method is capable of reducing the system complexity as well as improving its performance.

  15. Comparison of Hydrogen Peroxide Contact Lens Disinfection Systems and Solutions against Acanthamoeba polyphaga

    Science.gov (United States)

    Hughes, Reanne; Kilvington, Simon

    2001-01-01

    Acanthamoeba is a free-living amoeba causing a potentially blinding infection of the cornea. Contact lens wearers are most at risk and account for some 95% of cases. Hydrogen peroxide is used for contact lens disinfection due to its broad antimicrobial activity. Lenses must be neutralized before use to avoid pronounced stinging and possible corneal damage. Neutralization is achieved by adding a catalyst during the disinfection process (one-step) or afterwards (two-step). Here, the activities of commercial peroxide systems and individual solutions against trophozoites and cysts of Acanthamoeba polyphaga were compared. All disinfection systems were active against trophozoites, giving a ≥3-log (99.9%) kill within 1 h. Of the four one-step systems, only one showed some cysticidal activity, giving a 1.28 ± 0.41-log reduction. Both two-step systems were cysticidal, giving a ≥3-log kill at 4 h. All system peroxide solutions were cysticidal, giving a ≥3-log kill by 4 to 6 h. Variation in the cysticidal rate was observed with two solutions that gave a 1.8- to 2.1-log kill at 4 h compared with 3.0 to 4.0 for the rest (P sodium perborate or the contact lens protein remover subtilisin A. Two-step systems are cysticidal providing contact times of at least 4 h are employed. Variation in cyst killing occurs between peroxide solutions, possibly due to formulation differences. One-step systems are less effective against Acanthamoeba cysts due to rapid peroxide neutralization. The cysticidal activity of one-step systems could be improved if neutralization rates were retarded. PMID:11408220

  16. Polarization Monitoring of the Lens System JVAS B0218+357

    Directory of Open Access Journals (Sweden)

    Andrew Biggs

    2017-10-01

    Full Text Available Monitoring of the lens system JVAS B0218+357 with the Fermi Gamma-ray Space Telescope measured a different time delay to that derived from radio observations. We have re-analysed three months of archival Very Large Array data to produce variability curves with an average sampling of one epoch per day in total flux, polarized flux and polarization position angle (PPA at 15, 8.4 and 5 GHz. The variability is particularly strong in polarized flux. Dense sampling and improved subtraction of the Einstein ring has allowed us to produce superior variability curves and a preliminary analysis has resulted in a time delay (11.5 days which agrees well with the γ -ray value. Both images of 0218+357 are subject to strong Faraday rotation and depolarization as a result of the radio waves passing through the interstellar medium of the spiral lens galaxy. Our data reveal frequency-dependent variations in the PPA that are different in each image and which must therefore result from variable Faraday rotation in the lens galaxy on timescales of a few days. Our analysis has revealed systematic errors in the polarization position angle measurements that strongly correlate with hour angle. Although we have been able to correct for these, we caution that all VLA polarization observations are potentially affected.

  17. A new lens for supporting and studying science teacher reflections: situating the self in the [activity] system

    Science.gov (United States)

    Criswell, Brett; Calandra, Brendan; Puvirajah, Anton; Brantley-Dias, Laurie

    2015-12-01

    This paper presents a new lens for analyzing written reflections on the teaching experiences of pre-service [science] teachers. The lens, which borrows heavily from Activity Theory, allows science education researchers and teacher educators to identify tensions, disturbances, conflicts, and contradictions within teachers' written reflections as a means to help the participants situate their successes and challenges within the activity systems in which they operate. This paper describes the process through which the lens was crafted, defines the key constructs comprising the lens, applies the lens to the analysis of two purposefully selected reflection documents, and then considers the affordances of the lens. It also discusses how the insights gained from this lens have lead to new ways of facilitating reflection in pre-service science teachers, including the use of Kenneth Snelson's tensegrity sculptures as a metaphor for the goal of reflection. Finally, it connects the tensions identified in the individual reflections of two pre-service science teachers to broader issues being addressed in science education.

  18. Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system.

    Science.gov (United States)

    Yao, Jianing; Thompson, Kevin P; Ma, Bin; Ponting, Michael; Rolland, Jannick P

    2016-08-22

    In this paper, we develop the methodology, including the refraction correction, geometrical thickness correction, coordinate transformation, and layer segmentation algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index (S-GRIN) lens based on the imaging data collected by an angular scan optical coherence tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization and internal defect inspection of the lens. The metrology provides assessment of the surface geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the misalignment of the internal S-GRIN distribution with respect to the lens surface. The OCT metrology results identify the manufacturing defects, and enable targeted process development for optimizing the manufacturing parameters. The newly fabricated S-GRIN lenses show up to a 7x spherical aberration reduction that allows a significantly increased utilizable effective aperture.

  19. Associations of systemic diseases, smoking and contact lens wear with severity of dry eye.

    Science.gov (United States)

    Lee, Sze-Yee; Petznick, Andrea; Tong, Louis

    2012-11-01

    Systemic diseases, smoking, ocular surgeries and contact lens wear have been linked with dry eye but it is not known if these factors are also associated with severity of dry eye. A cross-sectional investigation was conducted on the effect of various systemic and ocular conditions with respect to the severity of dry eye in Asian patients. Prospective recruitment of consecutive new referral patients from a dry eye clinic was performed. Medical history, dry eye symptoms and clinical assessment were coded in a standardised form and analysed. Out of 510 patients (25% men), mean ± S.D. age 53.0 ± 14.1 years, 25 had previous diagnosis of rheumatoid arthritis, 30 had diabetic mellitus, 41 had thyroid disease, and 33 were current smokers; 23 and 41 patients had previous LASIK and cataract surgery respectively and 90 were current contact lenses wearers. A previous diagnosis of rheumatoid arthritis was associated with more severe superior corneal fluorescein staining (OR = 11.2, 95% CI 4.6-27.4). Generally, with the exception of rheumatoid arthritis, there were no associations between dry eye severity and systemic diseases, smoking, previous ocular surgeries and contact lens wear. Dry eye patients with rheumatoid arthritis tend to have more severe ocular surface damage in the superior cornea. Ophthalmic & Physiological Optics © 2012 Singapore Eye Research Institute.

  20. REFRACTIVE NEUTRON LENS

    OpenAIRE

    Petrov, P. V.; Kolchevsky, N. N.

    2013-01-01

    Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.

  1. A heterologous expression system for bovine lens transmembrane main intrinsic protein (MIP) in Nicotiana tabacum plants.

    Science.gov (United States)

    de Peyer, O S; Wetten, A C; Dunwell, J M; Crabbe, M J

    1999-10-29

    We have developed a heterologous expression system for transmembrane lens main intrinsic protein (MIP) in Nicotiana tabacum plant tissue. A native bovine MIP26 amplicon was subcloned into an expression cassette under the control of a constitutive Cauliflower Mosaic Virus promoter, also containing a neomycin phosphotransferase operon. This cassette was transformed into Agrobacterium tumefaciens by triparental mating and used to infect plant tissue grown in culture. Recombinant plants were selected by their ability to grow and root on kanamycin-containing media. The presence of MIP in the plant tissues was confirmed by PCR, RT-PCR and immunohistochemistry. A number of benefits of this system for the study of MIP will be discussed, and also its application as a tool for the study of heterologously expressed proteins in general.

  2. The rectenna design on contact lens for wireless powering of the active intraocular pressure monitoring system.

    Science.gov (United States)

    Cheng, H W; Jeng, B M; Chen, C Y; Huang, H Y; Chiou, J C; Luo, C H

    2013-01-01

    This paper proposed a wireless power harvesting system with micro-electro-mechanical-systems (MEMS) fabrication for noninvasive intraocular pressure (IOP) measurement on soft contact lens substructure. The power harvesting IC consists of a loop antenna, an impedance matching network and a rectifier. The proposed IC has been designed and fabricated by CMOS 0.18 um process that operates at the ISM band of 5.8 GHz. The antenna and the power harvesting IC would be bonded together by using flip chip bonding technologies without extra wire interference. The circuit utilized an impedance transformation circuit to boost the input RF signal that improves the circuit performance. The proposed design achieves an RF-to-DC conversion efficiency of 35% at 5.8 GHz.

  3. The use of femtosecond lasers in cataract surgery: review of the published results with the LenSx system.

    Science.gov (United States)

    Nagy, Zoltan Z; Mastropasqua, Leonardo; Knorz, Michael C

    2014-11-01

    To review the published literature describing the use of the LenSx femtosecond laser technology (Alcon Laboratories, Inc., Fort Worth, TX) in cataract surgery. Literature review. The LenSx system has been used in more than 200,000 cataract surgery procedures to date. Pre-clinical evaluations have shown that this system produces accurate and reproducible capsulorhexes, and that both the energy required for phacoemulsification and total phacoemulsification time are less than with conventional phacoemulsification. In comparative studies, femtosecond lasers have been shown to produce more precise and reproducible capsulorhexes than manual procedures, and better intraocular lens placement; capsule overlap, circularity of capsulotomy, and centration of the intraocular lens are consistently better with femtosecond lasers than with manual procedures. The improved quality of capsulorhexis and intraocular lens positioning are reflected in favorable visual and refractive outcomes. As with any new technology, there is a significant learning curve: prospective cohort studies have shown that the incidence of intraoperative complications such as suction breaks or anterior capsular tears or tags decreases with experience. In general, the incidence of such complications is within the range (surgery is in its infancy, the technology is evolving rapidly and offers the potential for more consistent and predictable results after cataract surgery. Copyright 2014, SLACK Incorporated.

  4. Research on aspheric focusing lens processing and testing technology in the high-energy laser test system

    Science.gov (United States)

    Liu, Dan; Fu, Xiu-hua; Jia, Zong-he; Wang, Zhe; Dong, Huan

    2014-08-01

    In the high-energy laser test system, surface profile and finish of the optical element are put forward higher request. Taking a focusing aspherical zerodur lens with a diameter of 100mm as example, using CNC and classical machining method of combining surface profile and surface quality of the lens were investigated. Taking profilometer and high power microscope measurement results as a guide, by testing and simulation analysis, process parameters were improved constantly in the process of manufacturing. Mid and high frequency error were trimmed and improved so that the surface form gradually converged to the required accuracy. The experimental results show that the final accuracy of the surface is less than 0.5μm and the surface finish is □, which fulfils the accuracy requirement of aspherical focusing lens in optical system.

  5. Research on the processing technology of medium-caliber aspheric lens in the optoelectronic integrated test system

    Science.gov (United States)

    Liu, Dan; Yu, Xin-ying; Wang, Wei

    2016-10-01

    In the optoelectronic integrated test system, surface profile and finish of the optical element are put forward higher request. Taking an aspherical quartz glass lens with a diameter of 200mm as example, taking Preston hypothesis as the theoretical basis, analyze the influence of surface quality of various process parameters, including the workpiece and the tool axis spindle speed, wheel type, concentration polishing, polishing mold species, dwell time, polishing pressure and other parameters. Using CNC method for the surface profile and surface quality of the lens were investigated. Taking profilometer measurement results as a guide, by testing and simulation analysis, process parameters were improved constantly in the process of manufacturing. Mid and high frequency error were trimmed and improved so that the surface form gradually converged to the required accuracy. The experimental results show that the final accuracy of the surface is less than 2µm and the surface finish is, which fulfils the accuracy requirement of aspherical focusing lens in optical system.

  6. The impact of a preloaded intraocular lens delivery system on operating room efficiency in routine cataract surgery.

    Science.gov (United States)

    Jones, Jason J; Chu, Jeffrey; Graham, Jacob; Zaluski, Serge; Rocha, Guillermo

    2016-01-01

    The aim of this study was to evaluate the operational impact of using preloaded intraocular lens (IOL) delivery systems compared with manually loaded IOL delivery processes during routine cataract surgeries. Time and motion data, staff and surgery schedules, and cost accounting reports were collected across three sites located in the US, France, and Canada. Time and motion data were collected for manually loaded IOL processes and preloaded IOL delivery systems over four surgery days. Staff and surgery schedules and cost accounting reports were collected during the 2 months prior and after introduction of the preloaded IOL delivery system. The study included a total of 154 routine cataract surgeries across all three sites. Of these, 77 surgeries were performed using a preloaded IOL delivery system, and the remaining 77 surgeries were performed using a manual IOL delivery process. Across all three sites, use of the preloaded IOL delivery system significantly decreased mean total case time by 6.2%-12.0% (Psystem also decreased surgeon lens time, surgeon delays, and eliminated lens touches during IOL preparation. Compared to a manual IOL delivery process, use of a preloaded IOL delivery system for cataract surgery reduced total case time, total surgeon lens time, surgeon delays, and eliminated IOL touches. The time savings provided by the preloaded IOL delivery system provide an opportunity for sites to improve routine cataract surgery throughput without impacting surgeon or staff capacity.

  7. Compliance among soft contact lens wearers.

    OpenAIRE

    Kuzman, Tomislav; Barišić Kutija, Marija; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurišić, Darija; Škegro, Ivan; Kalauz, Miro; Kordić, Rajko

    2014-01-01

    Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in ...

  8. Applying a family systems lens to proxy decision making in clinical practice and research.

    Science.gov (United States)

    Rolland, John S; Emanuel, Linda L; Torke, Alexia M

    2017-03-01

    When patients are incapacitated and face serious illness, family members must make medical decisions for the patient. Medical decision sciences give only modest attention to the relationships among patients and their family members, including impact that these relationships have on the decision-making process. A review of the literature reveals little effort to systematically apply a theoretical framework to the role of family interactions in proxy decision making. A family systems perspective can provide a useful lens through which to understand the dynamics of proxy decision making. This article considers the mutual impact of family systems on the processes and outcomes of proxy decision making. The article first reviews medical decision science's evolution and focus on proxy decision making and then reviews a family systems approach, giving particular attention to Rolland's Family Systems Illness Model. A case illustrates how clinical practice and how research would benefit from bringing family systems thinking to proxy decisions. We recommend including a family systems approach in medical decision science research and clinical practices around proxy decisions making. We propose that clinical decisions could be less conflicted and less emotionally troubling for families and clinicians if family systems approaches were included. This perspective opens new directions for research and novel approaches to clinical care. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  9. Decision Support System to Choose Digital Single Lens Camera with Simple Additive Weighting Method

    Directory of Open Access Journals (Sweden)

    Tri Pina Putri

    2016-11-01

    Full Text Available One of the technologies that evolve today is Digital Single Lens Reflex (DSLR camera. The number of products makes users have difficulties to choose the appropriate camera based on their criteria. Users may utilize several ways to help them choosing the intended camera such as using magazine, internet, and other media. This paper discusses about a web based decision support system to choose cameras by using SAW (Simple Additive Weighting method in order to make the decision process more effective and efficient. This system is expected to give recommendations about the camera which is appropriate with the user’s need and criteria based on the cost, the resolution, the feature, the ISO, and the censor. The system was implemented by using PHP and MySQL. Based on the result of questionnaire distributed to 20 respondents, 60% respondents agree that this decision support system can help users to choose the appropriate camera DSLR in accordance with the user’s need, 60% of respondents agree that this decision support system is more effective to choose DSLR camera and 75% of respondents agree that this system is more efficient. In addition, 60.55% of respondents agree that this system has met 5 Es Usability Framework.

  10. Gravitational lens system SDSS J1339+1310: microlensing factory and time delay

    Science.gov (United States)

    Goicoechea, L. J.; Shalyapin, V. N.

    2016-12-01

    We spectroscopically re-observed the gravitational lens system SDSS J1339+1310 using OSIRIS on the GTC. We also monitored the r-band variability of the two quasar images (A and B) with the LT over 143 epochs in the period 2009-2016. These new data in both the wavelength and time domains have confirmed that the system is an unusual microlensing factory. The C iv emission line is remarkably microlensed, since the microlensing magnification of B relative to that for A, μBA, reaches a value of 1.4 ( 0.4 mag) for its core. Moreover, the B image shows a red wing enhancement of C iv flux (relative to A), and μBA = 2 (0.75 mag) for the C iv broad-line emission. Regarding the nuclear continuum, we find a chromatic behaviour of μBA, which roughly varies from 5 (1.75 mag) at 7000 Å to 6 (1.95 mag) at 4000 Å. We also detect significant microlensing variability in the r band, and this includes a number of microlensing events on timescales of 50-100 d. Fortunately, the presence of an intrinsic 0.7 mag dip in the light curves of A and B, permitted us to measure the time delay between both quasar images. This delay is ΔtAB = 47 d (1σ confidence interval; A is leading), in good agreement with predictions of lens models. Tables 1-3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A77

  11. Commercially available rigid gas-permeable contact lens for protecting the cornea from drying during vitrectomy with a wide viewing system

    Directory of Open Access Journals (Sweden)

    Kamei M

    2012-08-01

    Full Text Available Motohiro Kamei, Nagakazu Matsumura, Hirokazu Sakaguchi, Yusuke Oshima, Yasushi Ikuno, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: We evaluated the usefulness of commercially available materials for protecting the cornea from drying during vitrectomy with a wide-angle viewing system.Methods: Three vitreoretinal surgeons evaluated fundus visibility during vitrectomy on the images of five study materials used on the cornea: balanced saline solution, a viscoelastic agent, a vitrectomy contact lens, a rigid gas permeable (RGP contact lens, and a soft contact lens. Fundus visibility was graded using the following scale: grade 1, unclear; grade 2, slightly unclear; grade 3, clear; and grade 4, very clear.Results: Respective scores for each material used during core vitrectomy and membrane removal were: balanced saline solution, 3.3/3.3; viscoelastic agent, 3.8/3.3; vitrectomy contact lens, 3.3/4.0; RGP contact lens, 4.0/3.9; soft contact lens, 1.1/not applicable.Conclusion: The RGP contact lens provided visibility similar to or clearer than that obtained with other methods. Because of its ease of use and lower cost, use of the RGP contact lens is ideal during vitrectomy performed with a wide-angle viewing system.Keywords: contact lens, RGP, viscoelastic agent, vitrectomy, wide viewing system

  12. Simulation model of a new solar laser system of Fresnel lens according to real observed solar radiation data in

    Directory of Open Access Journals (Sweden)

    Yasser A. Abdel-Hadi

    2015-12-01

    Full Text Available A new simulation model of a new solar pumped laser system was tested to be run in Helwan in Egypt (latitude φ = 29°52′N, longitude λ = 31°21′E and elevation = 141 m as an example of an industrial polluted area. The system is based on concentrating the solar radiation using a Fresnel lens on a laser head fixed on a mount tracking the sun during the day and powered by a DC battery. Two cases of this model are tested; the first one is the model consisting of a Fresnel lens and a two-dimensional Compound Parabolic Concentrator (CPC, while the other is the model consisting of a Fresnel lens and a three-dimensional Compound Parabolic Concentrator (CPC. The model is fed by real actual solar radiation data taken in Helwan Solar Radiation Station at NRIAG in the various seasons in order to know the laser power got from such a system in those conditions. For the system of Fresnel lens and 2D-CPC, an average laser output power of 1.27 W in Winter, 2 W in Spring, 5 W in Summer and 4.68 W in Autumn respectively can be obtained. Accordingly, the annual average output power for this system is 3.24 W. For the system of Fresnel lens and 3D-CPC, an average laser output power of 3.28 W in Winter, 3.55 W in Spring, 7.56 W in Summer and 7.13 W in Autumn respectively can be obtained. Accordingly, the annual average output power for this system is 5.38 W.

  13. Optical receiving system based on a compound parabolic concentrator and a hemispherical lens for visible light communication.

    Science.gov (United States)

    Wang, Yun; Lan, Tian; Ni, Guoqiang

    2016-12-20

    We propose a scheme for designing a new optical receiving system that can reduce the received-energy spot size via integration of a compound parabolic concentrator with a hemispherical lens. SolidWorks is used to model the receiving system, while TracePro is employed for simulations. The field of view is set to 30° and the radius of the compound parabolic concentrator outlet is 5 mm, which is also the radius of the hemispherical lens. Ray-tracing results show that under the given simulation conditions, the radius of the spot area is reduced from 5 to 3 mm at the receiving system and the gain is 5.2. In regard to the relations between received power and the radius of the hemispherical lens R, and the received power and the distance d between the compound parabolic concentrator and hemispherical lens, our detailed analysis yields the following characteristics: (1) the received power increases as R increases, but decreases as d increases; (2) as R increases, the spot area increases and the received flux is dispersed over the receiving plane, which dispersion is disadvantageous for high-speed communication; (3) the gain of the receiving system also varies with R and d; (4) an increase in d leads to decrease in the received flux and gain when d>-2  mm. Based on these characteristics, we set R=5  mm and calculate the energy efficiency. We obtain maximum energy efficiencies for different detection areas.

  14. An all-silicone zoom lens in an optical imaging system

    Science.gov (United States)

    Zhao, Cun-Hua

    2013-09-01

    An all-silicone zoom lens is fabricated. A tunable metal ringer is fettered around the side edge of the lens. A nylon rope linking a motor is tied, encircling the notch in the metal ringer. While the motor is operating, the rope can shrink or release to change the focal length of the lens. A calculation method is developed to obtain the focal length and the zoom ratio. The testing is carried out in succession. The testing values are compared with the calculated ones, and they tally with each other well. Finally, the imaging performance of the all-silicone lens is demonstrated. The all-silicone lens has potential uses in cellphone cameras, notebook cameras, micro monitor lenses, etc.

  15. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    Science.gov (United States)

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm.

  16. Biaxial-Type Concentrated Solar Tracking System with a Fresnel Lens for Solar-Thermal Applications

    Directory of Open Access Journals (Sweden)

    Tsung Chieh Cheng

    2016-04-01

    Full Text Available In this paper, an electromechanical, biaxial-type concentrated solar tracking system was designed for solar-thermal applications. In our tracking system, the sunlight was concentrated by the microstructure of Fresnel lens to the heating head of the Stirling engine and two solar cells were installed to provide the power for tracking system operation. In order to obtain the maximum sun power, the tracking system traces the sun with the altitude-azimuth biaxial tracing method and accurately maintains the sun’s radiation perpendicular to the plane of the heating head. The results indicated that the position of heating head is an important factor for power collection. If the sunlight can be concentrated to completely cover the heating head with small heat loss, we can obtain the maximum temperature of the heating head of the Stirling engine. Therefore, the temperature of heating head can be higher than 1000 °C in our experiment on a sunny day. Moreover, the results also revealed that the temperature decrease of the heating head is less than the power decrease of solar irradiation because of the latent heat of copper and the small heat loss from the heating head.

  17. Fabrication and evaluation of chalcogenide glass molding lens for car night-vision system

    Science.gov (United States)

    Cha, Du Hwan; Hwang, Yeon; Kim, Jeong-Ho; Kim, Hye-Jeong

    2013-05-01

    With the recent development of less costly uncooled detectors technology, expensive optics are among the remaining significant cost drivers. As a potential solution to this problem, the fabrication of IR lenses using chalcogenide glasses has been studied in recent years. We report on fabrication of molded chalcogenide-glass lens for car night-vision and on the evaluation of the lens. The moldability of chalcogenide glass was characterized through transcription properties of the mold's surface. In addition, both IR transmittance and XRD patterns of the molded chalcogenide glass lens were evaluated to verify the compositional and structural stability of the glass material at the corresponding molding condition.

  18. Rethinking contact lens aftercare.

    Science.gov (United States)

    Efron, Nathan; Morgan, Philip B

    2017-09-01

    The evolution of contact lens technology and clinical practice over the past three decades has been remarkable, with dramatic improvements in material biocompatibility, better lens designs and care systems, and more flexible and convenient modalities of wear. However, our approach to the aftercare examination has remained conservative, with the general modus operandi having not fully evolved from the difficult, early years of fitting non-regular replacement rigid and low water content hydrogel lenses. In this paper, we review current aftercare practice and in particular, the preferred frequency that lens wearers should return for routine visits and the appropriateness of regulations governing contact lens prescription expiry. Four key clinical reasons for conducting a routine aftercare visit are identified: preserving ocular health, maintaining good vision, optimising comfort and ensuring satisfactory lens fitting performance. Commercial reasons for conducting aftercare visits are also considered. A decision matrix is presented to help practitioners decide on an appropriate time interval between routine aftercare visits. The first aftercare visit should always take place within one to two weeks of lens dispensing. After this, the following time intervals between routine aftercare visits are advised as a general guideline: soft daily disposable, 24 months; soft daily reusable and rigid daily wear, 12 months; soft and rigid extended wear, six months. These aftercare visit frequencies may need to be adjusted when rapid rates of refractive change are anticipated, such as every six months during child/teenager myopic progression and every 12 months during the advancement of presbyopia. Numerous clinical caveats for varying these recommended aftercare frequencies are also discussed. Those new to lens wear should be seen within the first two months of lens dispensing. Regulatory authorities charged with the responsibility of stipulating the validity of a contact

  19. The impact of a preloaded intraocular lens delivery system on operating room efficiency in routine cataract surgery

    Directory of Open Access Journals (Sweden)

    Jones JJ

    2016-06-01

    Full Text Available Jason J Jones,1 Jeffrey Chu,2 Jacob Graham,2 Serge Zaluski,3 Guillermo Rocha4 1Jones Eye Clinic, Sioux City, IA, 2Quorum Consulting Inc., San Francisco, CA, USA; 3VISIS, Perpignan, France; 4Ocular Microsurgery & Laser Centre, Brandon, MB, Canada Purpose: The aim of this study was to evaluate the operational impact of using preloaded intraocular lens (IOL delivery systems compared with manually loaded IOL delivery processes during routine cataract surgeries. Methods: Time and motion data, staff and surgery schedules, and cost accounting reports were collected across three sites located in the US, France, and Canada. Time and motion data were collected for manually loaded IOL processes and preloaded IOL delivery systems over four surgery days. Staff and surgery schedules and cost accounting reports were collected during the 2 months prior and after introduction of the preloaded IOL delivery system. Results: The study included a total of 154 routine cataract surgeries across all three sites. Of these, 77 surgeries were performed using a preloaded IOL delivery system, and the remaining 77 surgeries were performed using a manual IOL delivery process. Across all three sites, use of the preloaded IOL delivery system significantly decreased mean total case time by 6.2%–12.0% (P<0.001 for data from Canada and the US and P<0.05 for data from France. Use of the preloaded delivery system also decreased surgeon lens time, surgeon delays, and eliminated lens touches during IOL preparation. Conclusion: Compared to a manual IOL delivery process, use of a preloaded IOL delivery system for cataract surgery reduced total case time, total surgeon lens time, surgeon delays, and eliminated IOL touches. The time savings provided by the preloaded IOL delivery system provide an opportunity for sites to improve routine cataract surgery throughput without impacting surgeon or staff capacity. Keywords: time and motion, provider impact, surgical throughput, IOL

  20. Telescopic vision contact lens

    Science.gov (United States)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  1. Design of no blind area perimeter intrusion recognition system based on fisheye lens

    Science.gov (United States)

    Dai, Jun-jian; Han, Wen-bo

    2013-08-01

    The Perimeter intrusion recognition technology has slowly become an indispensable function in the intelligent video surveillance system. The existed always use the multiple video acquisition nodes to respectively control a monitoring area and each node alarm independently. However, the existed solutions are difficult to avoid the existence of monitoring blind area, and can't suitable for the perimeter environment with irregular outline, and at the same time, because of the too many nodes, it inevitably decreased the overall accuracy of intrusion recognition system and increased the cost of system. To avoid the above defects, this paper mainly talks about the following three aspects. Firstly, we used the fisheye lens as the optical system of video acquisition node, and it evidently enhances each node's information acquisition ability. And in this way, we just need to decorate a small amount of video acquisition node to get no blind area environmental information of the perimeter when against a larger monitoring situation. Secondly, due to the inexistence of blind area, the system will have enough video image information to generate the 360 degree panoramic image for monitoring environment, and finally the system server collected the wide-angle image information to splice into the panoramic video image. Finally, the system will use the panoramic image to complete the intrusion behavior recognition, thus we can effectively avoid the parallel computation in many nodes independently invasion of recognition, and this can greatly reduces the dependence for the multiple CPU operation platform and enhances the reliability of the system. The field test results show that, with the help of this paper's solution, the perimeter of the invasion of recognition system can effectively avoids the recognition of blind area. In the same recognition algorithm and same level delay premise, it greatly reduces the monitoring system server configuration requirements, especially for the

  2. Comparing the Zeiss Callisto Eye and the Alcon Verion Image Guided System Toric Lens Alignment Technologies.

    Science.gov (United States)

    Hura, Arjan S; Osher, Robert H

    2017-07-01

    To compare the alignment meridian generated by the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA) and the Alcon Verion Image Guided System (Alcon Laboratories, Inc., Fort Worth, TX). In this retrospective comparative evaluation of technology, intraoperative images were captured at different steps in the same surgery, allowing the comparison of the guidance lines generated by the Verion system to the parallel guidance lines generated by the Callisto Eye system. Measurements of each hemi-meridian were quantified using Adobe Photoshop 2015 CC software (Adobe Systems, San Jose, CA). The numbers of degrees separating these alignment meridians were calculated, entered into a database, and analyzed. The authors found that of 98 captured images of 16 eyes, the two technologies were identical in 0 eyes (θ1 = θ2 = 0), similar by 3° in 52 (53%) captured images (θ1 ≠ θ2 ≠ 0), and different by at least 3° in 46 (47%) captured images (θ1 ≠ θ2 ≠ 0). The target meridians were superimposed, the target lines were minimally separated, and the target lines were dissimilar. It was noted that some intraoperative variation occurred from measurement to measurement. Within the small group of 16 cases of routine toric lens implantation in this study, the absolute average number of degrees of misalignment between the Verion and Callisto Eye systems was 3.355 for θ1 and 3.838 for θ2. On average, the intraoperative variation termed "drift" was noted to be 3.963° for θ1, and 4.557° for θ2. The authors found that small deviations were frequent when comparing two sophisticated technologies. Although deviations greater than 3° occurred in less than 47% of captured images from 16 eyes, smaller but significant variations of less than 3° occurred in 53% of captured images from 16 eyes. It was rare to identify a large deviation. However, the authors identified "drift" in the same eye when measurements were taken at different times. The results indicate that the two systems are

  3. Design and Optimization of Fresnel Lens for High Concentration Photovoltaic System

    Directory of Open Access Journals (Sweden)

    Lei Jing

    2014-01-01

    Full Text Available A practical optimization design is proposed, in which the solar direct light spectrum and multijunction cell response range are taken into account in combination, particularly for the Fresnel concentrators with a high concentration and a small aspect ratio. In addition, the change of refractive index due to temperature variation in outdoor operation conditions is also considered in the design stage. The calculation results show that this novel Fresnel lens achieves an enhancement of energy efficiency of about 10% compared with conventional Fresnel lens for a given solar spectrum, solar cell response, and corrected sunshine hours of different ambient temperature intervals.

  4. Sunglass Lens

    Science.gov (United States)

    1984-01-01

    Foster Grant's Space Technology Lens, manufactured under license from NASA, combines NASA technology with Foster Grant's own technology. The NASA contribution was a highly abrasion-resistant coating developed at Ames Research Center as a means of protecting plastic surfaces of aerospace equipment from the sometimes harsh environments to which they are subjected. The Space Tech Lens, now manufactured by Fosta-Tek, surpasses glass in abrasion resistant properties and has five times better scratch resistance than the most popular corrective lenses.

  5. The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses.

    Science.gov (United States)

    Shen, Elizabeth P; Tsay, Ruey-Yug; Chia, Jean-San; Wu, Semon; Lee, Jing-Wen; Hu, Fung-Rong

    2012-09-21

    To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL). Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM). Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P contact lens adhesion. ATF-incubated CL had significantly more bacterial adhesion (P contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.

  6. Lens Model

    DEFF Research Database (Denmark)

    Nash, Ulrik William

    2014-01-01

    Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of probabil......Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory...... of probabilistic functionalism, and concerns the environment and the mind, and adaptation by the latter to the former. This entry is about the lens model, and probabilistic functionalism more broadly. Focus will mostly be on firms and their employees, but, to fully appreciate the scope, we have to keep in mind...

  7. The effects of vitamin B6 on lens antioxidant system in valproic acid-administered rats.

    Science.gov (United States)

    Tunali, S

    2014-06-01

    Valproic acid (VPA, 2-propyl pentanoic acid) is a broad-spectrum antiepileptic drug (AED) and is commonly used in the treatment of bipolar disorders and epilepsy. AEDs are known to result in vascular disturbances. Vitamin B6 (Vit B6) is water soluble vitamin essential for normal growth, development, and metabolism. In this study, we aimed to investigate the protective effects of Vit B6 against VPA-induced lens damage in experimental animals. In this study, male 4-month-old, Sprague-Dawley rats were used. The animals were divided into four groups. Group I was intact control animals. Group II rats were administered with Vit B6 (50 mg/kg/day) for 7 days. Group III rats were administered with only VPA (500 mg/kg/day) for 7 days. Group IV was given VPA + Vit B6 (in a same dose and time). Vit B6 was given to rats by gavage and VPA was given by intraperitoneally. On the 8th day of experiment, all of the animals were fasted overnight and then killed under ether anesthesia. Lens tissues were taken from animals, homogenized in 0.9% saline to make up a 10% homogenate. The homogenates was used for glutathione (GSH), lipid peroxidation (LPO), protein levels, and enzyme analysis. In VPA groups, levels of lens GSH and LPO and activities of glutathione-S-transferase, glutathione peroxidase, glutathione reductase, and aldose reductase were increased, while superoxide dismutase activity was decreased. Treatment with Vit B6 reversed these effects. These results demonstrated that administration of Vit B6 is potentially beneficial agent to reduce the lens damage in VPA toxicity, probably by decreasing oxidative stress. © The Author(s) 2014.

  8. Using a complex adaptive system lens to understand family caregiving experiences navigating the stroke rehabilitation system.

    Science.gov (United States)

    Ghazzawi, Andrea; Kuziemsky, Craig; O'Sullivan, Tracey

    2016-10-01

    Family caregivers provide the stroke survivor with social support and continuity during the transition home from a rehabilitation facility. In this exploratory study we examined family caregivers' perceptions and experiences navigating the stroke rehabilitation system. The theories of continuity of care and complex adaptive systems were integrated to examine the transition from a stroke rehabilitation facility to the patient's home. This study provides an understanding of the interacting complexities at the macro and micro levels. A convenient sample of family caregivers (n = 14) who provide care for a stroke survivor were recruited 4-12 weeks following the patient's discharge from a stroke rehabilitation facility in Ontario, Canada. Interviews were conducted with family caregivers to examine their perceptions and experiences navigating the stroke rehabilitation system. Directed and inductive content analysis and the theory of Complex Adaptive Systems were used to interpret the perceptions of family caregivers. Health system policies and procedures at the macro-level determined the types and timing of information being provided to caregivers, and impacted continuity of care and access to supports and services at the micro-level. Supports and services in the community, such as outpatient physiotherapy services, were limited or did not meet the specific needs of the stroke survivors or family caregivers. Relationships with health providers, informational support, and continuity in case management all influence the family caregiving experience and ultimately the quality of care for the stroke survivor, during the transition home from a rehabilitation facility.

  9. Compliance among soft contact lens wearers.

    Science.gov (United States)

    Kuzman, Tomislav; Kutija, Marija Barisić; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurisić, Darija; Skegro, Ivan; Kalauz, Miro; Kordić, Rajko

    2014-12-01

    Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in different aspects of lens care handling and wearing habits. In our research 50 asymptomatic lens wearers filled out a questionnaire containing demographic data, lens type, hygiene and wearing habits, lenses and lens care system replacement schedule and self-evaluation of contact lens handling hygiene. We established criteria of compliance according to available manufacturer's recommendations, prior literature and our clinical experience. Only 2 (4%) of patients were fully compliant SCL wearers. The most common non-compliant behaviours were insufficient lens solution soaking time (62%), followed by failure to daily exchange lens case solution and showering while wearing lenses. 44% of patients reported storing lenses in saline solution. Mean lens storage case replacement was 3.6 months, with up to 78% patients replacing lens case at least once in 3 months. Average grade in self evaluating level of compliance was very good (4 +/- 0.78) (from 1-poor level of hygiene to 5-great level of hygiene). Lens wearers who reported excessive daily lens wear and more than 10 years of lens wearing experience were also found to be less compliant with other lens system care procedures. (t = -2.99, df=47, p lens system maintenance steps. Most common non-compliant behaviours were the ones that are crucial for maintaining lens sterility and preventing infection. Despite the low objective compliance rate, self grading was relatively high. Therefore, these results indicate the need for patient

  10. Measurement of lens density using Scheimpflug imaging system as a screening test in the field of health examination for age-related cataract.

    Science.gov (United States)

    Lim, Dong Hui; Kim, Tae Hyup; Chung, Eui-Sang; Chung, Tae-Young

    2015-02-01

    To assess Pentacam (Oculus, Wetzlar, Germany) Scheimpflug quantitative images in evaluating lens density and providing objective measurements to suggest optimal time of cataract surgery in the field of health examination. Two hundred and twenty-nine eyes with age-related cataract were enrolled. Lens density was measured using Pentacam. All Pentacam images were exported to ImageJ (NIH, Bethesda, Maryland, USA) for quantitative analysis. Average lens density (ALD) and nuclear lens density (NLD) were calculated. Lens density was also evaluated by built-in Pentacam Nucleus Staging (PNS) software. Slit-lamp microscopy was performed for cataract grading according to Lens Opacification Classification System III (LOCS III). The best-corrected visual acuity (BCVA) was measured. All measurements were compared between the cataract surgery and non-cataract surgery groups. The measurements of Pentacam images significantly correlated with LOCS III for nuclear opalescence (NO) and nuclear colour (NC) grading (pcataract surgery and non-surgery groups (pcataract surgery for mean NLD and maximum ALD were 26 and 74, respectively (pcataracts needing surgery. The method has the potential to be generally applied in the field of health examination and is effective in screening patients with cataract. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  11. Electrically tunable fluidic lens imaging system for laparoscopic fluorescence-guided surgery.

    Science.gov (United States)

    Volpi, Davide; Tullis, Iain D C; Barber, Paul R; Augustyniak, Edyta M; Smart, Sean C; Vallis, Katherine A; Vojnovic, Borivoj

    2017-07-01

    The addition of fluorescence guidance in laparoscopic procedures has gained significant interest in recent years, particularly through the use of near infrared (NIR) markers. In this work we present a novel laparoscope camera coupler based on an electrically tunable fluidic lens that permits programmable focus control and has desirable achromatic performance from the visible to the NIR. Its use extends the lower working distance limit and improves detection sensitivity, important for work with molecularly targeted fluorescence markers. We demonstrate its superior optical performance in laparoscopic fluorescence-guided surgery. In vivo results using a tumor specific molecular probe and a nonspecific NIR dye are presented.

  12. The BigLEN-GPR171 Peptide Receptor System Within the Basolateral Amygdala Regulates Anxiety-Like Behavior and Contextual Fear Conditioning.

    Science.gov (United States)

    Bobeck, Erin N; Gomes, Ivone; Pena, Darlene; Cummings, Kirstie A; Clem, Roger L; Mezei, Mihaly; Devi, Lakshmi A

    2017-12-01

    Studies show that neuropeptide-receptor systems in the basolateral amygdala (BLA) play an important role in the pathology of anxiety and other mood disorders. Since GPR171, a recently deorphanized receptor for the abundant neuropeptide BigLEN, is expressed in the BLA, we investigated its role in fear and anxiety-like behaviors. To carry out these studies we identified small molecule ligands using a homology model of GPR171 to virtually screen a library of compounds. One of the hits, MS0021570_1, was identified as a GPR171 antagonist based on its ability to block (i) BigLEN-mediated activation of GPR171 in heterologous cells, (ii) BigLEN-mediated hyperpolarization of BLA pyramidal neurons, and (iii) feeding induced by DREADD-mediated activation of BigLEN containing AgRP neurons in the arcuate nucleus. The role of GPR171 in anxiety-like behavior or fear conditioning was evaluated following systemic or intra-BLA administration of MS0021570_1, as well as following lentiviral-mediated knockdown of GPR171 in the BLA. We find that systemic administration of MS0021570_1 attenuates anxiety-like behavior while intra-BLA administration or knockdown of GPR171 in the BLA reduces anxiety-like behavior and fear conditioning. These results indicate that the BigLEN-GPR171 system plays an important role in these behaviors and could be a novel target to develop therapeutics to treat psychiatric disorders.

  13. Lens stem cells may reside outside the lens capsule: an hypothesis

    Directory of Open Access Journals (Sweden)

    Meyer Rita A

    2007-06-01

    Full Text Available Abstract In this paper, we consider the ocular lens in the context of contemporary developments in biological ideas. We attempt to reconcile lens biology with stem cell concepts and a dearth of lens tumors. Historically, the lens has been viewed as a closed system, in which cells at the periphery of the lens epithelium differentiate into fiber cells. Theoretical considerations led us to question whether the intracapsular lens is indeed self-contained. Since stem cells generate tumors and the lens does not naturally develop tumors, we reasoned that lens stem cells may not be present within the capsule. We hypothesize that lens stem cells reside outside the lens capsule, in the nearby ciliary body. Our ideas challenge the existing lens biology paradigm. We begin our discussion with lens background information, in order to describe our lens stem cell hypothesis in the context of published data. Then we present the ciliary body as a possible source for lens stem cells, and conclude by comparing the ocular lens with the corneal epithelium.

  14. Design and characterization of refractive secondary optical elements for a point-focus Fresnel lens-based high CPV system

    Science.gov (United States)

    Ferrer-Rodríguez, Juan P.; Baig, Hasan; Riverola, Alberto; Fernández, Eduardo F.; Chemisana, Daniel; Almonacid, Florencia; Mallick, Tapas K.; Pérez-Higueras, Pedro

    2017-09-01

    Point-focus Fresnel lens-based High Concentrator Photovoltaic (HCPV) systems are usually equipped with refractive secondary optical elements (SOE) in order to improve their performance. Two basic SOE designs are optically modeled and simulated in this work: Domed-Kaleidoscope (D-K) with breaking-symmetry top and SILO (SIngle-Lens-Optical element). Wavelength-dependent optical material properties like refractive index and absorption coefficient, as well as the spectral response of a typical triple-junction (TJ) solar cell, are included in the ray tracing simulations. Moreover, using a CPV Solar Simulator "Helios 3198", both HCPV units are experimentally characterized. The acceptance angle characteristics of both HCPV units, obtained through optical simulations and through indoor characterization, are compared. The acceptance angle characteristic is better for the HCPV unit with the D-K SOE both in simulations and in experimental measurements, showing concordance between simulation and experiment. However, simulation results underestimate the experimental ones concerning the acceptance angle, which will be investigated in future works.

  15. A new VLA/e-MERLIN limit on central images in the gravitational lens system CLASS B1030+074

    Science.gov (United States)

    Quinn, Jonathan; Jackson, Neal; Tagore, Amitpal; Biggs, Andrew; Birkinshaw, Mark; Chapman, Scott; De Zotti, Gianfranco; McKean, John; Pérez-Fournon, Ismael; Scott, Douglas; Serjeant, Stephen

    2016-07-01

    We present the new Very Large Array 22 GHz and extended Multi-Element Remote-Linked Interferometer Network 5 GHz observations of CLASS B1030+074, a two-image strong gravitational lens system whose background source is a compact flat-spectrum radio quasar. In such systems we expect a third image of the background source to form close to the centre of the lensing galaxy. The existence and brightness of such images is important for investigation of the central mass distributions of lensing galaxies, but only one secure detection has been made so far in a galaxy-scale lens system. The noise levels achieved in our new B1030+074 images reach 3 μJy beam-1 and represent an improvement in central image constraints of nearly an order of magnitude over previous work, with correspondingly better resulting limits on the shape of the central mass profile of the lensing galaxy. Simple models with an isothermal outer power-law slope now require either the influence of a central supermassive black hole (SMBH), or an inner power-law slope very close to isothermal, in order to suppress the central image below our detection limit. Using the central mass profiles inferred from light distributions in Virgo galaxies, moved to z = 0.5, and matching to the observed Einstein radius, we now find that 45 per cent of such mass profiles should give observable central images, 10 per cent should give central images with a flux density still below our limit, and the remaining systems have extreme demagnification produced by the central SMBH. Further observations of similar objects will therefore allow proper statistical constraints to be placed on the central properties of elliptical galaxies at high redshift.

  16. A Constructive Reframing of Student Roles and Systems Learning in Medical Education Using a Communities of Practice Lens.

    Science.gov (United States)

    Gonzalo, Jed D; Thompson, Britta M; Haidet, Paul; Mann, Karen; Wolpaw, Daniel R

    2017-12-01

    Health systems are in the midst of a transformation that is being driven by a variety of forces. This has important implications for medical educators because clinical practice environments play a key role in learning and professional development, and evolving health systems are beginning to demand that providers have "systems-ready" knowledge, attitudes, and skills. Such implications provide a clear mandate for medical schools to modify their goals and prepare physicians to practice flexibly within teams and effectively contribute to the improvement of health care delivery. In this context, the concepts of value-added medical education, authentic student roles, and health systems science are emerging as increasingly important. In this Article, the authors use a lens informed by communities of practice theory to explore these three concepts, examining the implications that the communities of practice theory has in the constructive reframing of educational practices-particularly common student roles and experiences-and charting future directions for medical education that better align with the needs of the health care system. The authors apply several key features of the communities of practice theory to current experiential roles for students, then propose a new approach to students' clinical experiences-value-added clinical systems learning roles-that provides students with opportunities to make meaningful contributions to patient care while learning health systems science at the patient and population level. Finally, the authors discuss implications for professional role formation and anticipated challenges to the design and implementation of value-added clinical systems learning roles.

  17. Modern lens antennas for communications engineering

    CERN Document Server

    Thornton, John

    2012-01-01

    The aim of this book is to present the modern design principles and analysis of lens antennas. It gives graduates and RF/Microwave professionals the design insights in order to make full use of lens antennas.  Why do we want to write a book in lens antennas? Because this topic has not been thoroughly publicized, its importance is underestimated. As antennas play a key role in communication systems, recent development in wireless communications would indeed benefit from the characteristics of lens antennas: low profile, and low cost etc.  The major advantages of lens antennas are na

  18. Propagation of flat-topped multi-Gaussian beams through a double-lens system with apertures.

    Science.gov (United States)

    Gao, Yanqi; Zhu, Baoqiang; Liu, Daizhong; Lin, Zunqi

    2009-07-20

    A general model for different apertures and flat-topped laser beams based on the multi-Gaussian function is developed. The general analytical expression for the propagation of a flat-topped beam through a general double-lens system with apertures is derived using the above model. Then, the propagation characteristics of the flat-topped beam through a spatial filter are investigated by using a simplified analytical expression. Based on the Fluence beam contrast and the Fill factor, the influences of a pinhole size on the propagation of the flat-topped multi-Gaussian beam (FMGB) through the spatial filter are illustrated. An analytical expression for the propagation of the FMGB through the spatial filter with a misaligned pinhole is presented, and the influences of the pinhole offset are evaluated.

  19. The SADI Personal Health Lens: A Web Browser-Based System for Identifying Personally Relevant Drug Interactions.

    Science.gov (United States)

    Vandervalk, Ben; McCarthy, E Luke; Cruz-Toledo, José; Klein, Artjom; Baker, Christopher J O; Dumontier, Michel; Wilkinson, Mark D

    2013-04-05

    The Web provides widespread access to vast quantities of health-related information that can improve quality-of-life through better understanding of personal symptoms, medical conditions, and available treatments. Unfortunately, identifying a credible and personally relevant subset of information can be a time-consuming and challenging task for users without a medical background. The objective of the Personal Health Lens system is to aid users when reading health-related webpages by providing warnings about personally relevant drug interactions. More broadly, we wish to present a prototype for a novel, generalizable approach to facilitating interactions between a patient, their practitioner(s), and the Web. We utilized a distributed, Semantic Web-based architecture for recognizing personally dangerous drugs consisting of: (1) a private, local triple store of personal health information, (2) Semantic Web services, following the Semantic Automated Discovery and Integration (SADI) design pattern, for text mining and identifying substance interactions, (3) a bookmarklet to trigger analysis of a webpage and annotate it with personalized warnings, and (4) a semantic query that acts as an abstract template of the analytical workflow to be enacted by the system. A prototype implementation of the system is provided in the form of a Java standalone executable JAR file. The JAR file bundles all components of the system: the personal health database, locally-running versions of the SADI services, and a javascript bookmarklet that triggers analysis of a webpage. In addition, the demonstration includes a hypothetical personal health profile, allowing the system to be used immediately without configuration. Usage instructions are provided. The main strength of the Personal Health Lens system is its ability to organize medical information and to present it to the user in a personalized and contextually relevant manner. While this prototype was limited to a single knowledge domain

  20. Conjunctival impression cytology in contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Simon Priya

    2002-01-01

    Full Text Available PURPOSE: To evaluate the cytological changes in conjunctiva following regular contact lens wear and to determine the correlation, if any, between severity of cytological alteration and symptoms related to contact lens wear. METHODS: One hundred eyes (50 normal asymptomatic subjects who served as a control group were studied by conjunctival impression cytology (CIC. These subjects were fitted with rigid gas permeable (RGP or soft contact lenses and were followed up at the end of 3 and 6 months. At each follow-up visit the CIC was repeated. A filter paper with the impression specimen was stained with periodic acid schiff (PAS and haematoxylin stain to study goblet cell loss. Papanicolaou stain was done to study squamous metaplasia. The cytological changes were graded using the system described by Natadisastra et al. RESULTS: Severity of cytological changes increased with the duration of contact lens wear (P = 0.00001. At the end of 6 months, 60% of symptomatic eyes wearing soft contact lens and RGP lens showed abnormal CIC changes. None of the asymptomatic RGP contact lens wearing eyes showed abnormal CIC changes whereas 33.4% of the asymptomatic soft contact lens wearing eyes showed abnormal CIC changes (P = 0.033. Epithelial changes occurred within 3-6 months of contact lens fitting. CONCLUSION: Severity of cytological changes increased with duration of lens wear (P = 0.00001. Prevalence and severity of cytological alteration is more in symptomatic contact lens wearers. Soft contact lens wearers although asymptomatic showed severe CIC changes.

  1. Exploring the effects of task shifting for HIV through a systems thinking lens: the case of Burkina Faso.

    Science.gov (United States)

    Yaya Bocoum, Fadima; Kouanda, Seni; Kouyaté, Bocar; Hounton, Sennen; Adam, Taghreed

    2013-10-22

    While the impact of task shifting on quality of care and clinical outcomes has been demonstrated in several studies, evidence on its impact on the health system as a whole is limited. This study has two main objectives. The first is to conceptualize the wider range of effects of task shifting through a systems thinking lens. The second is to explore these effects using task shifting for HIV in Burkina Faso as a case study. We used a case study approach, using qualitative research methods. Data sources included document reviews, reviews of available data and records, as well as interviews with key informants and health workers. In addition to the traditional measures of impact of task shifting on health outcomes, our study identified 20 possible effects of the strategy on the system as a whole. Moreover, our analysis highlighted the importance of differentiating between two types of health systems effects. The first are effects inherent to the task shifting strategy itself, such as job satisfaction or better access to health services. The second are effects due to health system barriers, for example the unavailability of medicines and supplies, generating a series of effects on the various components of the health system, e.g., staff frustration.Among the health systems effects that we found are positive, mostly unintended, effects and synergies such as increased health workers' sense of responsibility and worthiness, increased satisfaction due to using the newly acquired skills in other non-HIV tasks, as well as improved patient-provider relationships. Among the negative unintended effects are staff frustration due to lack of medicines and supplies or lack of the necessary infrastructure to be able to perform the new tasks. Our analysis highlights the importance of adopting a systems thinking approach in designing, implementing and evaluating health policies to mitigate some of the design issues or system bottle-necks that may impede their successful implementation

  2. Contact lens in keratoconus

    Directory of Open Access Journals (Sweden)

    Varsha M Rathi

    2013-01-01

    Full Text Available Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP lenses, soft and soft toric lenses, piggy back contact lenses (PBCL, hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

  3. Contact Lens Compliance

    OpenAIRE

    Jinabhai, A.

    2013-01-01

    Although contact lens-related complications are rare, and most are managed without any lasting side-effects, several reports have identified a variety of risk factors associated with lens wear complications. Among these risk factors, some are unalterable, such as age or gender. Others, however, are modifiable, for example, poor lens case hygiene or hand-washing and, therefore, can be targeted to maximise successful lens wear. This article reviews different aspects of contact lens non-compliance

  4. Eye lens dose correlations with personal dose equivalent and patient exposure in paediatric interventional cardiology performed with a fluoroscopic biplane system.

    Science.gov (United States)

    Alejo, L; Koren, C; Corredoira, E; Sánchez, F; Bayón, J; Serrada, A; Guibelalde, E

    2017-04-01

    To analyse the correlations between the eye lens dose estimates performed with dosimeters placed next to the eyes of paediatric interventional cardiologists working with a biplane system, the personal dose equivalent measured on the thorax and the patient dose. The eye lens dose was estimated in terms of Hp(0.07) on a monthly basis, placing optically stimulated luminescence dosimeters (OSLDs) on goggles. The Hp(0.07) personal dose equivalent was measured over aprons with whole-body OSLDs. Data on patient dose as recorded by the kerma-area product (PKA) were collected using an automatic dose management system. The 2 paediatric cardiologists working in the facility were involved in the study, and 222 interventions in a 1-year period were evaluated. The ceiling-suspended screen was often disregarded during interventions. The annual eye lens doses estimated on goggles were 4.13±0.93 and 4.98±1.28mSv. Over the aprons, the doses obtained were 10.83±0.99 and 11.97±1.44mSv. The correlation between the goggles and the apron dose was R2=0.89, with a ratio of 0.38. The correlation with the patient dose was R2=0.40, with a ratio of 1.79μSvGy-1cm-2. The dose per procedure obtained over the aprons was 102±16μSv, and on goggles 40±9μSv. The eye lens dose normalized to PKA was 2.21±0.58μSvGy-1cm-2. Measurements of personal dose equivalent over the paediatric cardiologist's apron are useful to estimate eye lens dose levels if no radiation protection devices are typically used. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. VizieR Online Data Catalog: LCs & spectra of SDSS J1515+1511 lens system (Shalyapin+, 2017)

    Science.gov (United States)

    Shalyapin, V. N.; Goicoechea, L. J.

    2017-09-01

    We conducted a photometric monitoring campaign of SDSS J1515+1511 from early February of 2014 to mid September of 2016, i.e., for 2.6yr with an average sampling rate of about two nights every week. All optical observations were performed with the 2.0m fully robotic Liverpool Telescope (LT) at the Roque de los Muchachos Observatory, Canary Islands (Spain). Deep long-slit spectra of SDSS J1515+1511 were obtained using the R500B and R500R grisms in the OSIRIS spectrograph on the 10.4m Gran Telescopio Canarias (GTC). We took a single 1800s exposure with the blue grism (R500B) on 2015 April 15. We also observed the lens system with the red grism (R500R) on 2015 April 16. Hence, the new data cover a wavelength range of 3570-9250Å with a resolving power of ~300-400. We observed SDSS J1515+1511 with the SPRAT long-slit spectrograph on 2015 August 16 (red grating) and 2015 August 18 (blue). We have re-observed the system on 2016 March 17 (blue). (5 data files).

  6. A course in lens design

    CERN Document Server

    Velzel, Chris

    2014-01-01

    A Course in Lens Design is an instruction in the design of image-forming optical systems. It teaches how a satisfactory design can be obtained in a straightforward way. Theory is limited to a minimum, and used to support the practical design work. The book introduces geometrical optics, optical instruments and aberrations. It gives a description of the process of lens design and of the strategies used in this process. Half of its content is devoted to the design of sixteen types of lenses, described in detail from beginning to end. This book is different from most other books on lens design because it stresses the importance of the initial phases of the design process: (paraxial) lay-out and (thin-lens) pre-design. The argument for this change of accent is that in these phases much information can be obtained about the properties of the lens to be designed. This information can be used in later phases of the design. This makes A Course in Lens Design a useful self-study book, and a suitable basis for an intro...

  7. Removal of noise and radial lens distortion during calibration of computer vision systems.

    Science.gov (United States)

    Wang, ZhenZhou

    2015-05-04

    The calibration of computer vision systems that contain the camera and the projector usually utilizes markers of the well-designed patterns to calculate the system parameters. Undesirably, the noise and radial distortion exist universally, which decreases the calibration accuracy and consequently decreases the measurement accuracy of the related technology. In this paper, a method is proposed to remove the noise and radial distortion by registering the captured pattern with an ideal pattern. After the optimal modeled pattern is obtained by registration, the degree of freedom of the total calibration markers is reduced to one and both the noise and radial distortion are removed successfully. The accuracy improvement in a structured light scanning system is over 10(24) order of magnitude in the sense of mean square errors. Most importantly, the proposed method can be readily adopted by the computer vision techniques that use projectors or cameras.

  8. Climate impacts, climate policies, and the role of adaptation through the lens of water systems

    Science.gov (United States)

    Hejazi, M. I.

    2016-12-01

    Recognizing the critical role of water in human-Earth system interactions, most integrated assessment models are moving to incorporate water within their modeling frameworks and climate change impacts more broadly. However, none of the IA models used in generating the four representative concentration pathways (RCPs) incorporated the potential feedbacks of water limitations on other modeled systems, meaning that these assessments did not consider the joint interactions between hydrologic and human systems simultaneously adapting to and mitigating climate change. Yet, hydrologic systems could impose severe limitations on both energy and land decisions. Also, previous efforts have been limited to taking information from IA and Earth system models and passing that information to global water management and hydrologic models with the implicit assumption that all unmet water demands are taken from non-renewable water resources, generally fossil groundwater. However, extracting and depleting water resources (e.g., aquifers) could have drastic impacts on both energy and land use systems and the ability to mitigate climate change. In this study, we use the Global Change Assessment Model (GCAM), where interactions between population, economic growth, energy, land and water resources interact simultaneously in a dynamically evolving system, to investigate: 1) how water scarcity affects energy and land use decisions as well as mitigation policies, 2) the effects of climate change impacts on the food-energy-water nexus, 3) how these impacts evolve in the context of the shared socioeconomic pathways (SSPs) with specific details on water technologies, 4) the effects of different adaptation measures and their associate investment costs, and 5) the relative contributions of climate and human systems on water scarcity. We find that previous estimates of global water withdrawal projections are overestimated, as our simulations show that it is more economical in some basins to alter

  9. Looking at Graduate Medical Education Through a Different Lens: A Health Care System's Perspective.

    Science.gov (United States)

    Roemer, Beth M; Azevedo, Theresa; Blumberg, Bruce

    2015-09-01

    In the era of the accountable care organization, U.S. models of physician practice are shifting from the solo, independent practitioner to the physician who is part of a multispecialty group practice or is employed by a health care institution, and from paper-based small offices to practice settings that emphasize technology-enabled, team-based systems of care. In this light, Kaiser Permanente's (KP's) long experience as an integrated, population-based health care delivery system makes it an increasingly relevant model in which to consider how graduate medical education (GME) can best prepare physicians for 21st-century health care. KP's multiple perspectives-as a GME setting, a health care delivery system, a health research enterprise, a community benefit organization, and the nation's largest private, multispecialty group practice of physicians-provide a multifaceted opportunity to consider GME in the context of health care transformation. The authors suggest that all participants in medical education have a role to play in preparing physicians for this future. They recommend that partnerships between universities and health care delivery systems serve as a highly effective model for education; that to better serve the needs of society, medical education institutions must adopt a broad community benefit mindset; and that, when medical groups and other institutions that employ physicians take the baton from GME, they need to commit to ongoing development and lifelong learning to enable their new physicians to reach their full potential.

  10. Exploring Teaching Programming Online through Web Conferencing System: The Lens of Activity Theory

    Science.gov (United States)

    Çakiroglu, Ünal; Kokoç, Mehmet; Kol, Elvan; Turan, Ebru

    2016-01-01

    The purpose of this qualitative study was to understand activities and behaviors of learners and instructor in an online programming course. Adobe Connect web conferencing system was used as a delivery platform. A total of fifty-six sophomore students attending a computer education and instructional technology program (online) participated in this…

  11. RETRACTED: Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system

    Science.gov (United States)

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Md Nasir, Mohd Hairul Nizam; Pavlović, Nenad T.; Akib, Shatirah

    2014-07-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor. Sections ;1. Introduction; and ;2. Modulation transfer function;, as well as Figures 1-3, plagiarize the article published by N. Gül and M. Efe in Turk J Elec Eng & Comp Sci 18 (2010) 71 (http://journals.tubitak.gov.tr/elektrik/issues/elk-10-18-1/elk-18-1-6-0811-9.pdf). Sections ;4. Adaptive neuro-fuzzy inference system; and ;6. Conclusion; duplicate parts of the articles previously published by the corresponding author et al in ;Expert Systems with Applications; 39 (2012) 13295-13304, http://dx.doi.org/10.1016/j.eswa.2012.05.072 and ;Expert Systems with Applications; 40 (2013) 281-286, http://dx.doi.org/10.1016/j.eswa.2012.07.076. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  12. A classification system of intraocular lens dislocation sites under operating microscopy, and the surgical techniques and outcomes of exchange surgery.

    Science.gov (United States)

    Hayashi, Ken; Ogawa, Soichiro; Manabe, Shin-Ichi; Hirata, Akira; Yoshimura, Koichi

    2016-03-01

    The aim of this study was to examine the recent status of intraocular lens (IOL) dislocation according to a classification system based on vertical dislocation position, as well as the surgical techniques and outcomes of IOL exchange surgery. The medical records of 230 eyes from 214 consecutive patients who experienced IOL dislocation and underwent exchange surgery between 2006 and 2014 were reviewed. Vertical dislocation sites observed preoperatively under operating microscopy were examined, along with the surgical techniques and outcomes of IOL exchange. Dislocation sites included (1) the anterior chamber (12.2 %), (2) pseudophakodonesis (19.1 %), (3) the anterior vitreous cavity (47.4 %), (4) trap door-like dislocation (dangling in the peripheral vitreous cavity; 16.1 %), and (5) the retinal surface (5.2 %). The IOL retained in the anterior segment was moved onto the iris by pulling it up through the limbal side ports with an anterior vitrectomy (67.8 %), or by pushing it up from the pars plana with an anterior vitrectomy (26.5 %), while the IOL dropped on the retina was lifting it up from the retina after pars plana vitrectomy (5.7 %). Mean uncorrected and distance-corrected visual acuity significantly improved postoperatively (p system, approximately 95 % of dislocated IOLs were retained in the anterior segment, and these IOLs were exchanged using an anterior approach through limbal incisions with an anterior vitrectomy. Visual acuity improved significantly, and serious complications were uncommon, probably because the IOL exchange techniques were standardized and simplified without pars plana vitrectomy.

  13. Microbiomes: unifying animal and plant systems through the lens of community ecology theory.

    Science.gov (United States)

    Christian, Natalie; Whitaker, Briana K; Clay, Keith

    2015-01-01

    The field of microbiome research is arguably one of the fastest growing in biology. Bacteria feature prominently in studies on animal health, but fungi appear to be the more prominent functional symbionts for plants. Despite the similarities in the ecological organization and evolutionary importance of animal-bacterial and plant-fungal microbiomes, there is a general failure across disciplines to integrate the advances made in each system. Researchers studying bacterial symbionts in animals benefit from greater access to efficient sequencing pipelines and taxonomic reference databases, perhaps due to high medical and veterinary interest. However, researchers studying plant-fungal symbionts benefit from the relative tractability of fungi under laboratory conditions and ease of cultivation. Thus each system has strengths to offer, but both suffer from the lack of a common conceptual framework. We argue that community ecology best illuminates complex species interactions across space and time. In this synthesis we compare and contrast the animal-bacterial and plant-fungal microbiomes using six core theories in community ecology (i.e., succession, community assembly, metacommunities, multi-trophic interactions, disturbance, restoration). The examples and questions raised are meant to spark discussion amongst biologists and lead to the integration of these two systems, as well as more informative, manipulatory experiments on microbiomes research.

  14. Microbiomes: unifying animal and plant systems through the lens of community ecology theory

    Science.gov (United States)

    Christian, Natalie; Whitaker, Briana K.; Clay, Keith

    2015-01-01

    The field of microbiome research is arguably one of the fastest growing in biology. Bacteria feature prominently in studies on animal health, but fungi appear to be the more prominent functional symbionts for plants. Despite the similarities in the ecological organization and evolutionary importance of animal-bacterial and plant–fungal microbiomes, there is a general failure across disciplines to integrate the advances made in each system. Researchers studying bacterial symbionts in animals benefit from greater access to efficient sequencing pipelines and taxonomic reference databases, perhaps due to high medical and veterinary interest. However, researchers studying plant–fungal symbionts benefit from the relative tractability of fungi under laboratory conditions and ease of cultivation. Thus each system has strengths to offer, but both suffer from the lack of a common conceptual framework. We argue that community ecology best illuminates complex species interactions across space and time. In this synthesis we compare and contrast the animal-bacterial and plant–fungal microbiomes using six core theories in community ecology (i.e., succession, community assembly, metacommunities, multi-trophic interactions, disturbance, restoration). The examples and questions raised are meant to spark discussion amongst biologists and lead to the integration of these two systems, as well as more informative, manipulatory experiments on microbiomes research. PMID:26441846

  15. Colored Contact Lens Dangers

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    Full Text Available ... lens. In Butler's case, the lenses caused an infection and left her with a corneal abrasion. "I ... lenses? Sep 13, 2017 Contact Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally ...

  16. KNOWLEDGE CONVERSION PADA PROSES PERENCANAAN PROYEK DI PT. LEN RAILWAY SYSTEM UNTUK STANDARDISASI PROSES DENGAN METODE SECI

    Directory of Open Access Journals (Sweden)

    Atikah Sayyidatu Nisaa

    2013-04-01

    Full Text Available PT LEN Railway System bergerak pada pembangunan proyek pensinyalan kereta api, namun pada proses perencanaan proyek pada perusahaan tersebut masih berupa tacit knowledge (pengalaman pekerja yang akan hilang. Oleh karena itu, diperlukan adanya konversi knowledge pekerja yang masih berbentuk tacit knowledge menjadi knowledge yang terdokumentasikan ke dalam bentuk explicit knowledge. Penelitian ini menggunakan metode SECI (Socialization, Externalization, Combination, Internalization. Pada tahap socialization dilakukan eksplorasi data kepada pelaku proyek yang bersangkutan mengenai proses bisnis suatu aktivitas maupun tacit dan explicit knowledge dari masing-masing aktivitas. Pada tahap externalization dilakukan pendokumentasian dari hasil eksplorasi data. Pada tahap combination dilakukan pemilihan best practice dengan menggunakan beberapa tools yaitu: metode Delphi, metode AHP dan pemilihan best practice menggunakan metode factor rating. Best practice yang didapatkan akan dikombinasikan dengan proses aktivitas dari PMBOK. Pada tahap internalization dilakukan penginformasian kepada pekerja mengenai best practice yang telah didapatkan dari hasil penelitian. Best practice yang terpilih dari hasil perhitungan factor rating didapatkan sebagai berikut best practice pembuatan WBS adalah proses bisnis dari responden 2 dengan nilai sebesar 8,710, untuk penentuan jadwal proyek dari responden 2 dengan nilai sebesar 8,067, untuk penentuan biaya proyek dari responden 3 sebesar 9,554, untuk pemilihan supplier dari responden 1 sebesar 8,330, untuk pembuatan desain proyek dari responden 1 sebesar 8,368 dan untuk pengadaan barang dari responden 1 dengan nilai sebesar 8,195. Kata Kunci : knowledge conversion, knowledge management, metode SECI Abstract The economic foundation movement of industrial era into the knowledge era has involved the project PT LEN Railway System which operates in the construction of the railway signaling project. This research uses SECI

  17. Activity systems modeling as a theoretical lens for social exchange studies

    Directory of Open Access Journals (Sweden)

    Ernest Jones

    2016-01-01

    Full Text Available The social exchange perspective seeks to acknowledge, understand and predict the dynamics of social interactions. Empirical research involving social exchange constructs have grown to be highly technical including confirmatory factor analysis to assess construct distinctiveness and structural equation modeling to assess construct causality. Each study seemingly strives to assess how underlying social exchange theoretic constructs interrelate. Yet despite this methodological depth and resultant explanatory and predictive power, a significant number of studies report findings that, once synthesized, suggest an underlying persistent threat of conceptual or construct validity brought about by a search for epistemological parsimony. Further, it is argued that a methodological approach that embraces inherent complexity such as activity systems modeling facilitates the search for simplified models while not ignoring contextual factors.

  18. Clustering Algorithms in Hybrid Recommender System on MovieLens Data

    Directory of Open Access Journals (Sweden)

    Kuzelewska Urszula

    2014-08-01

    Full Text Available Decisions are taken by humans very often during professional as well as leisure activities. It is particularly evident during surfing the Internet: selecting web sites to explore, choosing needed information in search engine results or deciding which product to buy in an on-line store. Recommender systems are electronic applications, the aim of which is to support humans in this decision making process. They are widely used in many applications: adaptive WWW servers, e-learning, music and video preferences, internet stores etc. In on-line solutions, such as e-shops or libraries, the aim of recommendations is to show customers the products which they are probably interested in. As input data the following are taken: shopping basket archives, ratings of the products or servers log files.

  19. Networked Community Change: Understanding Community Systems Change through the Lens of Social Network Analysis.

    Science.gov (United States)

    Lawlor, Jennifer A; Neal, Zachary P

    2016-06-01

    Addressing complex problems in communities has become a key area of focus in recent years (Kania & Kramer, 2013, Stanford Social Innovation Review). Building on existing approaches to understanding and addressing problems, such as action research, several new approaches have emerged that shift the way communities solve problems (e.g., Burns, 2007, Systemic Action Research; Foth, 2006, Action Research, 4, 205; Kania & Kramer, 2011, Stanford Social Innovation Review, 1, 36). Seeking to bring clarity to the emerging literature on community change strategies, this article identifies the common features of the most widespread community change strategies and explores the conditions under which such strategies have the potential to be effective. We identify and describe five common features among the approaches to change. Then, using an agent-based model, we simulate network-building behavior among stakeholders participating in community change efforts using these approaches. We find that the emergent stakeholder networks are efficient when the processes are implemented under ideal conditions. © Society for Community Research and Action 2016.

  20. Decision support system for determining the contact lens for refractive errors patients with classification ID3

    Science.gov (United States)

    Situmorang, B. H.; Setiawan, M. P.; Tosida, E. T.

    2017-01-01

    Refractive errors are abnormalities of the refraction of light so that the shadows do not focus precisely on the retina resulting in blurred vision [1]. Refractive errors causing the patient should wear glasses or contact lenses in order eyesight returned to normal. The use of glasses or contact lenses in a person will be different from others, it is influenced by patient age, the amount of tear production, vision prescription, and astigmatic. Because the eye is one organ of the human body is very important to see, then the accuracy in determining glasses or contact lenses which will be used is required. This research aims to develop a decision support system that can produce output on the right contact lenses for refractive errors patients with a value of 100% accuracy. Iterative Dichotomize Three (ID3) classification methods will generate gain and entropy values of attributes that include code sample data, age of the patient, astigmatic, the ratio of tear production, vision prescription, and classes that will affect the outcome of the decision tree. The eye specialist test result for the training data obtained the accuracy rate of 96.7% and an error rate of 3.3%, the result test using confusion matrix obtained the accuracy rate of 96.1% and an error rate of 3.1%; for the data testing obtained accuracy rate of 100% and an error rate of 0.

  1. Understanding adaptive capacity and capacity to innovate in social-ecological systems: Applying a gender lens.

    Science.gov (United States)

    Cohen, Philippa J; Lawless, Sarah; Dyer, Michelle; Morgan, Miranda; Saeni, Enly; Teioli, Helen; Kantor, Paula

    2016-12-01

    Development policy increasingly focuses on building capacities to respond to change (adaptation), and to drive change (innovation). Few studies, however, focus specifically on the social and gender differentiation of capacities to adapt and innovate. We address this gap using a qualitative study in three communities in Solomon Islands; a developing country, where rural livelihoods and well-being are tightly tied to agriculture and fisheries. We find the five dimensions of capacity to adapt and to innovate (i.e. assets, flexibility, learning, social organisation, agency) to be mutually dependant. For example, limits to education, physical mobility and agency meant that women and youth, particularly, felt it was difficult to establish relations with external agencies to access technical support or new information important for innovating or adapting. Willingness to bear risk and to challenge social norms hindered both women's and men's capacity to innovate, albeit to differing degrees. Our findings are of value to those aspiring for equitable improvements to well-being within dynamic and diverse social-ecological systems.

  2. [Contact lens care and maintenance].

    Science.gov (United States)

    Bloise, L

    2017-04-01

    All contact lenses with replacement schedules longer than daily must be maintained. At each step of their use, the lenses may be contaminated. Contact lens solutions perform the essential functions of cleaning, decontaminating and preserving the lenses to prevent infectious problems and improve wearing comfort. Contact lens contamination essentially comes from hands, cleaning solutions, cases, water and the environment. The pathogenic microorganisms are mainly Gram-negative bacteria, fungi and amoebae. Contact lens deposits may or may not have an organic origin. Their presence increases the risk of infection because they serve as a nutrient matrix for microbes, and they are responsible for wearing discomfort. Contact lens solutions differ in their composition, their mechanism of action and the concentration of the various agents. To prescribe the best lens care system to each wearer and for each material, it is necessary to be very familiar with them. Maintenance is the main cause of discomfort with contact lenses, either through improper use, solution-material incompatibility, or a reaction of the wearer to the components. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Structural Conditions for Collaboration and Learning in Innovation Networks: Using an Innovation System Performance Lens to Analyse Agricultural Knowledge Systems

    NARCIS (Netherlands)

    Hermans, F.; Klerkx, L.W.A.; Roep, D.

    2015-01-01

    Purpose: We investigate how the structural conditions of eight different European agricultural innovation systems can facilitate or hinder collaboration and social learning in multidisciplinary innovation networks. Methodology: We have adapted the Innovation System Failure Matrix to investigate the

  4. Improvement of Varioptic's liquid lens based on electrowetting: how to obtain a short response time and its application in the design of a high resolution iris biometric system

    Science.gov (United States)

    Burger, Benjamin; Meimon, Serge C.; Petit, Cyril; Nguyen, Minh Chau

    2015-02-01

    This communication presents the results obtained for decreasing the response time of electrowetting-based real time focus correctors (liquid lenses). In order to provide a compact iris biometric system demonstrator, we have achieved a response time at 90% of 7.5 ms for a change in focalization from 0 diopter to 10 diopter with a liquid lens having an aperture of 1.9 mm. We have used a hydrodynamic fluid reorganization model to predict the features of these fast liquid lenses and evaluated the sensivity of the response time to the different conception parameters.

  5. Effective X-ray beam size measurements of an X-ray tube and polycapillary X-ray lens system using a scanning X-ray fluorescence method

    Energy Technology Data Exchange (ETDEWEB)

    Gherase, Mihai R., E-mail: mgherase@csufresno.edu; Vargas, Andres Felipe

    2017-03-15

    Size measurements of an X-ray beam produced by an integrated polycapillary X-ray lens (PXL) and X-ray tube system were performed by means of a scanning X-ray fluorescence (SXRF) method using three different metallic wires. The beam size was obtained by fitting the SXRF data with the analytical convolution between a Gaussian and a constant functions. For each chemical element in the wire an effective energy was calculated based on the incident X-ray spectrum and its photoelectric cross section. The proposed method can be used to measure the effective X-ray beam size in XRF microscopy studies.

  6. Contact lens in keratoconus

    OpenAIRE

    Rathi, Varsha M; Preeji S Mandathara; Srikanth Dumpati

    2013-01-01

    Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the En...

  7. A Two-Dimensional Model for Tear Flow through a Permeable Contact Lens

    Science.gov (United States)

    Gerhart, Matthew; Anderson, Daniel

    2011-11-01

    This is an investigation into the flow of an incompressible fluid in a thin pre-lens, contact lens, and post-lens system. The pre-lens and post-lens layers are coupled through the middle layer being a thin permeable contact lens. Included in this system are the effects of evaporation of the pre-lens film and the settling of the contact lens over time. This analysis is done through the nondimensionalization of the governing equations which include the Navier-Stokes equations for the pre- and post-lens tear film and Darcy's equations for the contact lens layer along with heat equations for temperature. Lubrication theory is then applied to the resulting system leaving a reduced coupled system of equations whose properties we explore. Supported by NSF-DMS.

  8. Experimental Investigation on the Feasibility of Using a Fresnel Lens as a Solar-Energy Collection System for Enhancing On-Orbit Power Generation Performance

    Directory of Open Access Journals (Sweden)

    Tae-Yong Park

    2017-01-01

    Full Text Available Cube satellites have a limitation for generating power because of their cubic structure and extremely small size. In addition, the incidence angle between the sun and the solar panels continuously varies owing to the revolution and rotation of the satellite according to the attitude control strategy. This angle is an important parameter for determining the power generation performance of the cube satellite. In this study, we performed an experimental feasibility study that uses a Fresnel lens as a solar-energy collection system for cube satellite applications, so that the power generation efficiency can be enhanced under the worst incidence angle condition between the sun and solar panels by concentrating and redirecting solar energy onto the solar panels with a commercial Fresnel lens. To verify the effectiveness of the proposed system, we conducted a power-measurement test using a solar simulator and Fresnel lenses at various angles to the light source. In addition, we predicted the on-orbit power-generation enhancement achieved by employing the solar-energy collection system with various attitude control strategies.

  9. Lens Design Using Group Indices of Refraction

    Science.gov (United States)

    Vaughan, A. H.

    1995-01-01

    An approach to lens design is described in which the ratio of the group velocity to the speed of light (the group index) in glass is used, in conjunction with the more familiar phase index of refraction, to control certain chromatic properties of a system of thin lenses in contact. The first-order design of thin-lens systems is illustrated by examples incorporating the methods described.

  10. Numerical studies of triplet and Russian quadruplet quadrupole lens systems with the given spot size on the target, for use in a microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Brazhnik, V.A.; Lebed, S.A.; Ponomarev, A.G.; Storizhko, V.E. [Ukrainian Academy of Sciences, Sumy (Ukraine). Applied Physics Institute; Dymnikov, A.D. [University of St Petersburg, Stary (Russian Federation). Institute of Computational Mathematics and Control Processes; Jamieson, D.N.; Legge, S.A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1993-12-31

    In a nuclear microprobe the focusing system is an essential component which determines the beam spot size, i.e. the microprobe resolution. A small beam cross section at the target is the most important of the many conflicting requirements imposed on the beam The second most important factor is the current of the beam which at the given brightness is proportional to the phase volume (or emittance) of the beam. Existing microprobes frequently use a triplet or a Russian quadruplet as the focusing systems. This paper describes the numerical studies of some optimal quadrupole lens systems consisting of three or four lenses suitable for use in a nuclear microprobe taking into account geometrical aberrations of third order. The maximum emittance of changed particle beams for these systems has been found. It is shown how the maximum emittance depends on the spot size. 2 refs., 2 figs.

  11. ECTOPIC LENS EXTRACTION IN CHILDREN

    Directory of Open Access Journals (Sweden)

    Vladimir Pfeifer

    2002-12-01

    Full Text Available Background. Ectopia lentis continues to be a therapeutic challenge for ophthalmologists. It can occur as an isolated condition, after ocular trauma, in association with other ocular disorders, as part of a systemic mesodermal disease or a complication of general metabolic disorders. Minimal subluxation of the lens may cause no visual symptoms, but in more advanced cases serious optical disturbances arise. The most important is amblyopia. Surgical treatment options include iris manipulation, lens discission, aspiration, intracapsular or extracapsular extraction, and pars plana lensectomy. The choice of surgical technique remains controversial, in part because of the historically poor visual results and high rate of perioperative complications, including vitreous loss and retinal detachment.Methods. We describe a surgical technique based on the use of the Cionni endocapsular tension ring, dry irrigation aspiration of lens material, centration of the capsular bag and foldable intraocular lens implantation into the bag. With mentioned surgical technique 8 patients were operated; 4 boys and 4 girls, together 11 eyes.Results. The final BCVA after follow up period improved in 9 eyes and it remained the same as before operation in one eye. Statistical comparison of preoperative and postoperative visual acuities showed significant improvement. On the other hand there was no correlation between preoperative and postoperative visual acuity.Conclusions. This surgical procedure is an alternative approach in solving this challenging cases of ectopia lentis with good postoperative visual rehabilitation.

  12. Colored Contact Lens Dangers

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    Full Text Available ... level of care or consideration as a standard contact lens because they can be purchased over-the-counter ... Teenager Blinded In One Eye By Non-Prescription Contact Lens Laura: Vision Loss After Just 10 Hours Robyn: ...

  13. Colored Contact Lens Dangers

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    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct 31, 2016 What You Should Know About Swimming and Your Eyes Aug 16, 2016 5 Steps to Healthy Contact Lens Use May 31, 2016 More Eye Health News Eyeglasses May One Day Treat Glaucoma JAN 18, ...

  14. Artificial crystalline lens

    NARCIS (Netherlands)

    Norrby, S.; Koopmans, S.; Terwee, T.

    2006-01-01

    Replacement of the crystalline lens with a synthetic soft material (ACL) has been shown to produce 3 to 5 D of accommodation following pharmacologic stimulation in primates for up to 1 year postoperatively. The eyes were relatively clear, suggesting that an injectable synthetic lens is a feasible

  15. Colored Contact Lens Dangers

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    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct 31, 2016 What You Should Know About Swimming and Your Eyes Aug 16, 2016 5 Steps to Healthy Contact Lens Use May 31, 2016 More Eye Health News Top ...

  16. Contact lens hygiene compliance and lens case contamination: A review.

    Science.gov (United States)

    Wu, Yvonne Tzu-Ying; Willcox, Mark; Zhu, Hua; Stapleton, Fiona

    2015-10-01

    A contaminated contact lens case can act as a reservoir for microorganisms that could potentially compromise contact lens wear and lead to sight threatening adverse events. The rate, level and profile of microbial contamination in lens cases, compliance and other risk factors associated with lens case contamination, and the challenges currently faced in this field are discussed. The rate of lens case contamination is commonly over 50%. Coagulase-negative Staphylococcus, Bacillus spp., Pseudomonas aeruginosa and Serratia marcescens are frequently recovered from lens cases. In addition, we provide suggestions regarding how to clean contact lens cases and improve lens wearers' compliance as well as future lens case design for reducing lens case contamination. This review highlights the challenges in reducing the level of microbial contamination which require an industry wide approach. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  17. Subjective assessment of contact lens wear by army aircrew.

    Science.gov (United States)

    Lattimore, M R; Cornum, R L

    1993-07-01

    Because 23% of Army aviators are ametropic, contact lenses have drawn increased attention as a spectacle substitute to solve system compatibility problems. From November 1988 until October 1991, a series of contact lens research protocols were conducted to develop a comprehensive database on contact lens wear in varied environments. Questionnaires were used to assess suitability and acceptability of routine contact lens wear. Responses from 202 subjects were obtained from September 1989 through September 1991. The questions explored operational and safety of flight issues of contact lens wear. Subjects overwhelmingly approved of contact lens use in all settings: 95% expressed greater combat readiness and effectiveness with contact lenses, 98% felt contact lens use (and maintenance) in the cockpit had no adverse impact on safety of flight, and 98% endorsed the routine use of contact lenses. These data highlight Army aircrew acceptance of contact lens use.

  18. Small capsulotomy and great implant lens.

    Science.gov (United States)

    Budo, C; Montanus, F

    1991-01-01

    The envelope technique provokes in all cases a rupture of the zonules. With capsulorhexis, the advantages of working inside the envelope are lost, but the zonules are better protected. The capsulokleisis--or similar capsulotomies--combines the advantages of both systems. The Miyake technique indicates that the ideal lens for the capsular bag is a circular lens filling completely the capsular bag like the phacodrop.

  19. Double lens collimator solar feedback sensor and master slave configuration: Development of compact and low cost two axis solar tracking system for CPV applications

    KAUST Repository

    Burhan, Muhammad

    2016-08-31

    The conventional CPV systems, as big unit design, are only suitable to be installed in the open regions, like desert areas. This gigantic system design restricts their use on the rooftop of commercial and residential buildings, unlike the conventional PV systems. This paper proposes a compact but highly accurate and cheap two axis solar tracking system, designed for CPV system field operation. The proposed system is designed and verified for tracking accuracy requirement of 0.3 degrees, and has maximum capability of as high as 0.1 degrees tracking accuracy. High tracking accuracy is ensured using in-house built double lens collimator solar feedback sensor, within a fraction of the cost of commercial solar tracking sensors. A hybrid tracking algorithm is developed in C-programming using astronomical and optical solar tracking methods. As compact CPV system design demands larger number of tracking units, for same power capacity of system. Therefore, a master slave control configuration is also proposed for the CPV field operation. Only master tracker will be equipped with the expensive tracking devices, while the required tracking information will be sent to all of the slave trackers using wireless communication through ZigBee devices. With detailed optical design, simulation and control strategy, a prototype of the proposed CPV tracking system is developed, experimentally investigated and verified for tracking accuracy for outdoor operation at the rooftop. (C) 2016 Elsevier Ltd. All rights reserved.

  20. Colored Contact Lens Dangers

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  2. Colored Contact Lens Dangers

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    Full Text Available ... Purchase the colored contact lenses from an eye product retailer who asks for a prescription. Follow the contact lens care directions for cleaning, disinfecting, and wearing the lenses. Never share contact ...

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  15. Colored Contact Lens Dangers

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    Full Text Available ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. ...

  16. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct ... Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American Academy of Ophthalmology 2017 ...

  17. Viscous froth lens

    Science.gov (United States)

    Green, T. E.; Bramley, A.; Lue, L.; Grassia, P.

    2006-11-01

    Microscale models of foam structure traditionally incorporate a balance between bubble pressures and surface tension forces associated with curvature of bubble films. In particular, models for flowing foam microrheology have assumed this balance is maintained under the action of some externally imposed motion. Recently, however, a dynamic model for foam structure has been proposed, the viscous froth model, which balances the net effect of bubble pressures and surface tension to viscous dissipation forces: this permits the description of fast-flowing foam. This contribution examines the behavior of the viscous froth model when applied to a paradigm problem with a particularly simple geometry: namely, a two-dimensional bubble “lens.” The lens consists of a channel partly filled by a bubble (known as the “lens bubble”) which contacts one channel wall. An additional film (known as the “spanning film”) connects to this bubble spanning the distance from the opposite channel wall. This simple structure can be set in motion and deformed out of equilibrium by applying a pressure across the spanning film: a rich dynamical behavior results. Solutions for the lens structure steadily propagating along the channel can be computed by the viscous froth model. Perturbation solutions are obtained in the limit of a lens structure with weak applied pressures, while numerical solutions are available for higher pressures. These steadily propagating solutions suggest that small lenses move faster than large ones, while both small and large lens bubbles are quite resistant to deformation, at least for weak applied back pressures. As the applied back pressure grows, the structure with the small lens bubble remains relatively stiff, while that with the large lens bubble becomes much more compliant. However, with even further increases in the applied back pressure, a critical pressure appears to exist for which the steady-state structure loses stability and unsteady

  18. Patient comfort following thirty minutes of lens wear: piggy-back versus conventional rigid-lens wear

    Directory of Open Access Journals (Sweden)

    W. D.H. Gillan

    2014-08-01

    Full Text Available Discomfort when wearing contact lenses, especially rigid contact lenses, is a common complaint amongst neophyte as well as experienced contact lens wearers. Wearing a piggy-back system of contact lenses has been shown to improve comfort and wearing time, especially in keratoconic subjects. Twenty two normal subjects wore a rigid lens or a piggy-back system of lenses for thirty minutes and after a thirty minute break swopped the mode of lens wear and wore the second modality for a thirty minute period. This study suggests that a piggy-back lens system provides improved comfort compared to wearing a rigid lens on its own. The order of lens wear might, however, influence the perceived comfort.

  19. The design of contact lens based ocular drug delivery systems for single-day use: Part (I) Structural factors, surrogate ophthalmic dyes and passive diffusion studies.

    Science.gov (United States)

    Mahomed, Anisa; Tighe, Brian J

    2014-09-01

    The poor retention and efficacy of instilled drops as a means of delivering drugs to the ophthalmic environment is well-recognised. The potential value of contact lenses as a means of ophthalmic drug delivery, and consequent improvement of pre-corneal retention is one obvious route to the development of a more effective ocular delivery system. Furthermore, the increasing availability and clinical use of daily disposable contact lenses provides the platform for the development of viable single-day use drug delivery devices based on existing materials and lenses. In order to provide a basis for the effective design of such devices, a systematic understanding of the factors affecting the interaction of individual drugs with the lens matrix is required. Because a large number of potential structural variables are involved, it is necessary to achieve some rationalisation of the parameters and physicochemical properties (such as molecular weight, charge, partition coefficients) that influence drug interactions. Ophthalmic dyes and structurally related compounds based on the same core structure were used to investigate these various factors and the way in which they can be used in concert to design effective release systems for structurally different drugs. Initial studies of passive diffusional release form a necessary precursor to the investigation of the features of the ocular environment that over-ride this simple behaviour. Commercially available contact lenses of differing structural classifications were used to study factors affecting the uptake of the surrogate actives and their release under 'passive' conditions. The interaction between active and lens material shows considerable and complex structure dependence, which is not simply related to equilibrium water content. The structure of the polymer matrix itself was found to have the dominant controlling influence on active uptake; hydrophobic interaction with the ophthalmic dye playing a major role. © The

  20. In-the-Spectacle-Lens Telescopic Device

    Science.gov (United States)

    Peli, Eli; Vargas-Martín, Fernando

    2008-01-01

    Spectacle-mounted telescopic systems are prescribed for individuals with visual impairments. Bioptic telescopes are typically mounted toward the top of the spectacle lens (or above the frame) with the telescope eyepiece positioned above the wearer’s pupil. This allows the wearer to use up and down head tilt movements to quickly alternate between the unmagnified wide view (through the carrier lens) and the magnified narrow field-of-view (available through the eyepiece). Rejection of this visual aid has been attributed mainly to its appearance and to the limited field-of-view through the smaller Galilean designs. We designed a wide-field Keplerian telescope that is built completely within the spectacle lens. The design uses embedded mirrors inside the carrier lens for optical pathway folding and conventional lenses or curved mirrors for magnification power. The short height of the ocular, its position, and a small tilt of the ocular mirror enable the wearer to simultaneously view the magnified field above the unmagnified view of the uninterrupted horizontal field. These features improve the cosmetics and utility of the device. The in-the-lens design will allow the telescope to be mass-produced as a commodity ophthalmic lens blank that can be surfaced to include the wearer’s spectacle prescription. PMID:18601572

  1. Role of Aquaporin 0 in lens biomechanics.

    Science.gov (United States)

    Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  2. Role of Aquaporin 0 in lens biomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu Kumari, S.; Gupta, Neha [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Shiels, Alan [Washington University School of Medicine, St. Louis, MO (United States); FitzGerald, Paul G. [Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA (United States); Menon, Anil G. [University of Cincinnati College of Medicine, Cincinnati, OH (United States); Mathias, Richard T. [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States)

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  3. H0LiCOW - II. Spectroscopic survey and galaxy-group identification of the strong gravitational lens system HE 0435-1223

    Science.gov (United States)

    Sluse, D.; Sonnenfeld, A.; Rumbaugh, N.; Rusu, C. E.; Fassnacht, C. D.; Treu, T.; Suyu, S. H.; Wong, K. C.; Auger, M. W.; Bonvin, V.; Collett, T.; Courbin, F.; Hilbert, S.; Koopmans, L. V. E.; Marshall, P. J.; Meylan, G.; Spiniello, C.; Tewes, M.

    2017-10-01

    Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H0 from the time-delay technique. We present the results of a systematic spectroscopic identification of the galaxies in the field of view of the lensed quasar HE 0435-1223 using the W. M. Keck, Gemini and ESO-Very Large telescopes. Our new catalogue triples the number of known galaxy redshifts in the direct vicinity of the lens, expanding to 102 the number of measured redshifts for galaxies separated by less than 3 arcmin from the lens. We complement our catalogue with literature data to gather redshifts up to 15 arcmin from the lens, and search for galaxy groups or clusters projected towards HE 0435-1223. We confirm that the lens is a member of a small group that includes at least 12 galaxies, and find 8 other group candidates near the line of sight of the lens. The flexion shift, namely the shift of lensed images produced by high-order perturbation of the lens potential, is calculated for each galaxy/group and used to identify which objects produce the largest perturbation of the lens potential. This analysis demonstrates that (i) at most three of the five brightest galaxies projected within 12 arcsec of the lens need to be explicitly used in the lens models, and (ii) the groups can be treated in the lens model as an external tidal field (shear) contribution.

  4. Preliminary of Optical Lens Design for Micro-Satellite

    Science.gov (United States)

    Rachim, Elvira; Mukhtar Tahir, Andi; Herawan, Agus

    2017-01-01

    The development of micro satellites for the last two decades is emerging rapidly as the need of satellite communication usage is increasing. Earth observation is one of the example of how satellites are on demand. Most observation satellites consist of sensors and imaging system on-board. One of the key element to have a good imaging system is a special optical lens system design. Such lens is designed specifically by calculating every parameter such as refractive, reflective indexes, type of surface, distance and many more. Manufactured lenses sometimes do not match the requirement of an imager system hence the special lens design is needed. This paper will first briefly describe the history of optic, theory related to lens system, then the design and the analysis of lens system for micro-satellites generally and LAPAN A4 particularly.

  5. Water use efficiency in medicinal pumpkin (Cucurbita pepo L. var. styriac/ chickpea (Cicer arietinum L.- lentil (Lens esculenta Moench. intercropping system associated with several nitrogen levels

    Directory of Open Access Journals (Sweden)

    M. Khoramivafa

    2016-05-01

    Full Text Available Although the physiological and morphological differences between intercropped species caused a higher WUE possibly, most researches on multiple cropping systems have focused on yields and the resources use efficiency (water, light and nutrients has been less investigated. In addition, optimal use of nitrogen is important to attain sustainable agriculture due to its role in WUE improvement. The experiment carried out during 2008 growing season as split plot based on RCBD design. The main plots included different nitrogen levels (0, 75, 100 and 125 kg.ha-1, which applied as urea and sub plots were three cropping systems consist of sole cropping of pumpkin (Cucurbita pepo L. var. styriac seed and intercropped with four rows of lentil (Lens esculenta Moench. and or chickpea (Cicer arieinum L.. The results showed that WUE and evapo-transpiration efficiency of medicinal pumpkin was affected by N application significantly. However no differences were observed between cropping systems with regard to total water use, WUE and evapo-transpiration efficiency. Intercropping has no significant effect on total water use, therefore, medicinal pumpkin/ chickpea- lentil intercropping systems can be recommended without any concern in terms of increasing of water consumption.

  6. An inverse and analytic lens design method

    CERN Document Server

    Lu, Yang

    2016-01-01

    Traditional lens design is a numerical and forward process based on ray tracing and aberration theory. This method has limitations because the initial configuration of the lens has to be specified and the aberrations of the lenses have to considered. This paper is an initial attempt to investigate an analytic and inverse lens design method, called Lagrange, to overcome these barriers. Lagrange method tries to build differential equations in terms of the system parameters and the system input and output (object and image). The generalized Snell's law in three dimensional space and the normal of a surface in fundamental differential geometry are applied. Based on the Lagrange method equations for a single surface system are derived which can perfectly image a point object.

  7. RHIC electron lens test bench diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Gassner, D.; Beebe, E.; Fischer, W.; Gu, X.; Hamdi, K.; Hock, J.; Liu, C.; Miller, T.; Pikin, A.; Thieberger, P.

    2011-05-16

    An Electron Lens (E-Lens) system will be installed in RHIC to increase luminosity by counteracting the head-on beam-beam interaction. The proton beam collisions at the RHIC experimental locations will introduce a tune spread due to a difference of tune shifts between small and large amplitude particles. A low energy electron beam will be used to improve luminosity and lifetime of the colliding beams by reducing the betatron tune shift and spread. In preparation for the Electron Lens installation next year, a test bench facility will be used to gain experience with many sub-systems. This paper will discuss the diagnostics related to measuring the electron beam parameters.

  8. Disposable contact lenses vs. contact lens maintenance for extended wear.

    Science.gov (United States)

    Josephson, J E; Caffery, B E; Campbell, I; Slomovic, A R

    1990-01-01

    We compared a disposable extended wear contact lens modality with conventional extended wear over a 6-week period. To do so, we refit 31 patients who had successfully worn conventional extended wear contact lenses for more than 1 year. One eye was fit with the AcuvueR disposable contact lens, and a new extended wear lens of the type the patient had been wearing was placed on the other eye. At weekly intervals the disposable lens was discarded and a new disposable lens inserted. At the same time, the conventional lens on the fellow eye was cleaned, disinfected, and reinserted. After 6 weeks the ocular response, subjective impressions, and condition of the lenses in the two eyes were compared. Both lenses were then cultured. Three subjects had to discontinue disposable lens wear because of adverse reactions to trapped cellular debris and corneal microcysts. Although the results were not statistically significant, the Acuvue lens appeared to perform better than or equal to the conventional lens in biomicroscopic observation, visual acuity measurement, and subjective patient preference. Eighty-seven percent of patients preferred to continue with the disposable system. There were no differences found in the type or degree of microbial contamination of the lenses.

  9. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... an Ophthalmologist Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact ... After One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter ...

  10. Contact Lens Risks

    Science.gov (United States)

    ... any lens solution. Do not expose your contact lenses to any water: tap, bottled, distilled, lake or ocean water. Never ... resistant to treatment and cure. Remove your contact lenses before swimming. ... in swimming pool water, hot tubs, lakes and the ocean Replace your ...

  11. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... in the United States. All contact lenses are medical devices that require a prescription and proper fitting by an eye-care professional. ... care professional such as an ophthalmologist — an eye medical doctor — who will ... a valid prescription that includes the brand name, lens measurements, and ...

  12. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... or in beauty salons, novelty shops or in pop-up Halloween stores are not FDA-approved and are ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct ...

  13. Characterizing contact lens-related dryness symptoms in a cross-section of UK soft lens wearers.

    Science.gov (United States)

    Young, Graeme; Chalmers, Robin L; Napier, Leslie; Hunt, Chris; Kern, Jami

    2011-04-01

    To estimate the prevalence of and factors associated with contact lens-related dryness symptoms in a large population of soft contact lens patients in the UK. Soft contact lens (CL) wearers (n=932) from 12 UK clinical sites were queried regarding CL history and wearing experience by a self-administered questionnaire. A new score using Contact Lens Dry Eye Questionnaire (CLDEQ) items was used where CL-related dry eye (CL-DE)=frequency of 'sometimes', 'frequently', or 'constantly' plus intensity 3-5; NoCL-DE=frequency of 'never' or 'rarely' and intensity 0-1; Marginal CL-DE, all other categories. Data were analyzed across categories, P-values lens wearers (n=129) compared to spherical lens wearers (43% vs. 30%, P=0.04). Lens material class, lens care system and gender were not significantly related to CL-DE status. Of the CL-DE group, only 38% had been diagnosed with dry eye and 47% self-assessed as dry eye. Use of artificial tears, CLs for dryness, ointments/gels and warm compresses differed between groups according to CL-DE status (PContact Lens Association. Published by Elsevier Ltd. All rights reserved.

  14. Clinical survey of lens care in contact lens patients.

    Science.gov (United States)

    Ky, W; Scherick, K; Stenson, S

    1998-10-01

    Overall, contact lenses provide a safe and effective modality for vision correction. However, problems do occasionally arise. Up to 80% of contact lens complications can be traced to poor patient compliance with recommended lens care guidelines. We conducted a survey to evaluate the level of patient compliance in specific areas of lens care and maintenance and to assess patient knowledge of basic contact lens information. Patients were asked to complete an anonymous 15 question survey that focused on lens care--specifically the use of contact lens cleaners, methods of disinfection, enzyme treatments, use of rewetting drops, and the frequency of follow-up exams. In addition, the survey included six true/false questions relating to contact lens care and safety. There were a total of 103 participants in the study. Approximately 24% of patients stated they never cleaned their lenses prior to disinfection, and 5% used saline solutions as their primary mode of disinfection. A sizable portion of those surveyed (43% of soft lens wearers and 71% of rigid gas permeable lens wearers) either never used enzyme cleaners or used them less than once a month. Seventy percent of patients either never used rewetting drops or used them less than once a day. Twenty-nine percent of patients consulted their eye care professionals every 2 years and 6% less often than every two years. Six questions assessed patient knowledge of contact lens care safety. Of a possible six out of six correct answers, the mean number of correct responses was 3.74. A sizable proportion of contact lens wearers do not adequately adhere to recommended contact lens care, and many have an inadequate understanding of contact lens care guidelines. Therefore, it is important that practitioners place more emphasis on patient education at the time of initial contact lens fitting and reinforce such instruction during follow-up visits.

  15. Contact lens fitting following corneal graft surgery.

    Science.gov (United States)

    Szczotka, Loretta B; Lindsay, Richard G

    2003-07-01

    Contact lens fitting may be required following keratoplasty for either optical or therapeutic reasons. Optical indications for contact lens fitting include the correction of irregular astigmatism, high regular astigmatism, anisometropia and secondary aniseikonia, as well as simple ametropia, where the patient desires to wear contact lenses in preference to spectacles. Therapeutic lenses are not routinely fitted following keratoplasty, although this management is advised in certain cases, such as when there are protruding sutures or epithelial healing is impaired. Designing a contact lens for a patient who has undergone keratoplasty will require the practitioner to carefully assess all the relevant features of the corneal graft. In this regard, there are many factors that need to be considered including the diameter of the graft zone, the topographical relationship between the host cornea and donor cornea, the corneal (graft) toricity and the location of the graft. Special designs, such as reverse geometry lenses, or more complex contact lens modalities, such as piggyback contact lens systems, may be required to achieve success in fitting.

  16. ERP implementation - Seeing through a lens : A comparative literature review regarding the factors that influence a successful ERP system implementation.

    OpenAIRE

    Rashidzadeh Azar, Soran; Chaudhry, Muhammad Irfan

    2010-01-01

    Purpose: The purpose of this thesis is to describe and analyse the factors that contribute to the successful ERP system implementation, the stakeholders of ERP system and how these stakeholders are related to CSFs of ERP system implementation. Design/ methodology/ approach: The research methodology approach chosen for this research is based on reality and clear research which includes qualitative and quantitative method for collecting and analysing data. Data for this research consists of sec...

  17. Newborn mouse lens proteome and its alteration by lysine 6 mutant ubiquitin

    Science.gov (United States)

    Ubiquitin is a tag that often initiates degradation of proteins by the proteasome in the ubiquitin proteasome system. Targeted expression of K6W mutant ubiquitin (K6W-Ub) in the lens results in defects in lens development and cataract formation, suggesting critical functions for ubiquitin in lens. T...

  18. [Correct contact lens hygiene].

    Science.gov (United States)

    Blümle, S; Kaercher, T; Khaireddin, R

    2013-06-01

    Although contact lenses have long been established in ophthalmology, practical aspects of handling contact lenses is becoming increasingly less important in the clinical training as specialist for ophthalmology. Simultaneously, for many reasons injuries due to wearing contact lenses are increasing. In order to correct this discrepancy, information on contact lenses and practical experience with them must be substantially increased from a medical perspective. This review article deals with the most important aspects for prevention of complications, i.e. contact lens hygiene.

  19. School Systems' Practices of Controlling Socialization during Principal Succession: Looking through the Lens of an Organizational Socialization Theory

    Science.gov (United States)

    Bengtson, Ed; Zepeda, Sally J.; Parylo, Oksana

    2013-01-01

    The importance of effective school leadership is well known. The inevitable changing of school leaders raises concerns over the successfulness of the succession process. Directly linked to leader succession is socialization; therefore, the purpose of this study was to examine the processes and practices of school systems that control the…

  20. Contact lens and tear film dynamics during blinking

    Science.gov (United States)

    Reid, Timothy; Anderson, Daniel

    2016-11-01

    We develop a mathematical model that couples the dynamics of the tear film and contact lens during blinking. We derive an ordinary differential equation for the motion of the contact lens (parallel to the cornea) driven and retarded by viscous forces in the thin fluid films separating the contact lens from the eyelids and the corneal surface. Using the contact lens motion and tear film dynamics models we calculate a numerical solution of tear film thickness, showing that the lens and lid motion influence the tear film dynamics. The numerical solution uses a mapped Chebyshev spectral method for the spatial derivatives to reduce the model to a system of differential algebraic equations. National Science Foundation Grants (DMS-1407087) and (DMS-1107848).

  1. Design of LED projector based on gradient-index lens

    Science.gov (United States)

    Qian, Liyong; Zhu, Xiangbing; Cui, Haitian; Wang, Yuanhang

    2018-01-01

    In this study, a new type of projector light path is designed to eliminate the deficits of existing projection systems, such as complex structure and low collection efficiency. Using a three-color LED array as the lighting source, by means of the special optical properties of a gradient-index lens, the complex structure of the traditional projector is simplified. Traditional components, such as the color wheel, relay lens, and mirror, become unnecessary. In this way, traditional problems, such as low utilization of light energy and loss of light energy, are solved. With the help of Zemax software, the projection lens is optimized. The optimized projection lens, LED, gradient-index lens, and digital micromirror device are imported into Tracepro. The ray tracing results show that both the utilization of light energy and the uniformity are improved significantly.

  2. Planar optical correlators integrated with binary optical lens.

    Science.gov (United States)

    Xu, Ping; Hong, Chunquan; Cheng, Guanxiao; Zhou, Liang; Sun, Zhilong

    2015-03-09

    Planar optical correlators (POCs) can achieve smaller volume of optical system and hence have important applications to identify dynamic targets in complex scenarios. POCs, however, generally have serious astigmatism and optical efficiency loss introduced by its refractive lens with a zigzag optical beam. To conquer the disadvantages of POCs, we propose a type of binary optical planar-integrated optical correlator. The correlator incorporates two pieces of reflective binary optical lens as Fourier transform lens and one spatial light modulator as a programmable filter. The off-axis aberrations commonly occurred in POCs can be corrected by using reflective binary optical lens instead of refractive lens. As a model of hybrid numerical-optical correlator using optoelectronic interface, the proposal is helpful to improve the integration and flexibility and robustness of POCs.

  3. Thick lens chromatic effective focal length variation versus bending

    Science.gov (United States)

    Sparrold, Scott

    2017-11-01

    Longitudinal chromatic aberration (LCA) can limit the optical performance in refractive optical systems. Understanding a singlet's chromatic change of effective focal leads to insights and methods to control LCA. Long established, first order theory, shows the chromatic change in focal length for a zero thickness lens is proportional to it's focal length divided by the lens V number or inverse dispersion. This work presents the derivation of an equation for a thick singlet's chromatic change in effective focal length as a function of center thickness, t, dispersion, V, index of refraction, n, and the Coddington shape factor, K. A plot of bending versus chromatic focal length variation is presented. Lens thickness does not influence chromatic variation of effective focal length for a convex plano or plano convex lens. A lens's center thickness'influence on chromatic focal length variation is more pronounced for lower indices of refraction.

  4. THE BOSS EMISSION-LINE LENS SURVEY. IV. SMOOTH LENS MODELS FOR THE BELLS GALLERY SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Yiping [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Bolton, Adam S.; Montero-Dorta, Antonio D.; Cornachione, Matthew A.; Zheng, Zheng; Brownstein, Joel R. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States); Mao, Shude [Physics Department and Tsinghua Centre for Astrophysics, Tsinghua University, Beijing 100084 (China); Kochanek, Christopher S. [Department of Astronomy and Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Pérez-Fournon, Ismael; Marques-Chaves, Rui [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 San Cristóbal de La Laguna, Tenerife (Spain); Oguri, Masamune [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ménard, Brice, E-mail: yiping.shu@nao.cas.cn [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2016-12-20

    We present Hubble Space Telescope F606W-band imaging observations of 21 galaxy-Ly α emitter lens candidates in the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Ly α EmitteR sYstems (BELLS GALLERY) survey. Seventeen systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately 0.55, while the lensed sources are Ly α emitters (LAEs) at redshifts from two to three. Although most of the lens systems are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are, on average, 60% larger than those of the BELLS lenses because of the much higher source redshifts. This will allow for a detailed investigation of the radius evolution of the mass profile in ETGs. With the aid of the average ∼13× lensing magnification, the LAEs are frequently resolved into individual star-forming knots with a wide range of properties. They have characteristic sizes from less than 100 pc to several kiloparsecs, rest-frame far-UV apparent AB magnitudes from 29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.

  5. Different effects of the hypolipidemic drugs pravastatin and lovastatin on the cholesterol biosynthesis of the human ocular lens in organ culture and on the cholesterol content of the rat lens in vivo

    NARCIS (Netherlands)

    Vries, A.C.J. de; Cohen, L.H.

    1993-01-01

    This study aimed to investigate the influence of the hypocholesterolemic drugs pravastatin and lovastatin on the cholesterol biosynthesis in the ocular lens. Two model systems were used: a human lens organ culture system and an in vivo rat lens system. For measurements of cholesterol and fatty acid

  6. An adjustable electron achromat for cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-12-15

    Chromatic aberration correction in light optics began with the invention of a two-color-corrected achromatic crown/flint lens doublet by Chester Moore Hall in 1730. Such color correction is necessary because any single glass shows dispersion (i.e. its index of refraction changes with wavelength), which can be counteracted by combining different glasses with different dispersions. In cathode lens microscopes (such as Photo Electron Emission Microscopy – PEEM) we encounter a similar situation, where the chromatic aberration coefficient of the cathode lens shows strong dispersion, i.e. depends (non-linearly) on the energy with which the electrons leave the sample. Here I show how a cathode lens in combination with an electron mirror can be configured as an adjustable electron achromat. The lens/mirror combination can be corrected at two electron energies by balancing the settings of the electron mirror against the settings of the cathode lens. The achromat can be adjusted to deliver optimum performance, depending on the requirements of a specific experiment. Going beyond the achromat, an apochromat would improve resolution and transmission by a very significant margin. I discuss the requirements and outlook for such a system, which for now remains a wish waiting for fulfilment. - Highlights: • The properties of cathode objective lens plus electron mirror are discussed. • In analogy with light-optical achromats, cathode lens plus mirror can be configured as an electron achromat. • Unlike light optics, the electron achromat can be adjusted to best fulfill experimental requirements.

  7. Prolonging contact lens wear and making contact lens wear safer.

    Science.gov (United States)

    Foulks, Gary N

    2006-02-01

    To summarize the present status of safety and efficacy of contact lens wear. Literature review. Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses. Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses. The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

  8. Health system frailties in tuberculosis service provision in Russia: an analysis through the lens of formal nutritional support.

    Science.gov (United States)

    Coker, R J; Dimitrova, B; Drobniewski, F; Samyshkin, Y; Pomerleau, J; Hohlova, G Y; Skuratova, N; Kuznetsov, S; Fedorin, I; Atun, R

    2005-09-01

    The aim of this study was to describe health system challenges faced by tuberculosis (TB) treatment facilities in Russia through an analysis of formal institutional dietary provisions to patients in an inpatient facility that provides care for poor patients. Analysis of formal dietary provisions by institutions and financing data from TB hospitals in Samara Oblast, Russia. Formal dietary provision for inpatients with TB has fallen substantially in recent years. In a hospital providing inpatient care for the poorest patients with fewest social support networks, this has been very pronounced. The likely reason for this is that financial support for other budget lines, principally salaries, has required protection. Formal institutional nutritional support in institutions providing care for the poorest patients with TB is unlikely to be enhancing the speed of recovery, or reducing the duration of infectiousness. Furthermore, the role that hospital may have played in the past in enabling patients to regain weight lost before admission may have been limited by reductions in formal financing. Reductions in state provision of food for patients may serve as an important illustration of wider TB control system frailties in the Russian Federation.

  9. Precision diagnosis: a view of the clinical decision support systems (CDSS) landscape through the lens of critical care.

    Science.gov (United States)

    Belard, Arnaud; Buchman, Timothy; Forsberg, Jonathan; Potter, Benjamin K; Dente, Christopher J; Kirk, Allan; Elster, Eric

    2017-04-01

    Improving diagnosis and treatment depends on clinical monitoring and computing. Clinical decision support systems (CDSS) have been in existence for over 50 years. While the literature points to positive impacts on quality and patient safety, outcomes, and the avoidance of medical errors, technical and regulatory challenges continue to retard their rate of integration into clinical care processes and thus delay the refinement of diagnoses towards personalized care. We conducted a systematic review of pertinent articles in the MEDLINE, US Department of Health and Human Services, Agency for Health Research and Quality, and US Food and Drug Administration databases, using a Boolean approach to combine terms germane to the discussion (clinical decision support, tools, systems, critical care, trauma, outcome, cost savings, NSQIP, APACHE, SOFA, ICU, and diagnostics). References were selected on the basis of both temporal and thematic relevance, and subsequently aggregated around four distinct themes: the uses of CDSS in the critical and surgical care settings, clinical insertion challenges, utilization leading to cost-savings, and regulatory concerns. Precision diagnosis is the accurate and timely explanation of each patient's health problem and further requires communication of that explanation to patients and surrogate decision-makers. Both accuracy and timeliness are essential to critical care, yet computed decision support systems (CDSS) are scarce. The limitation arises from the technical complexity associated with integrating and filtering large data sets from diverse sources. Provider mistrust and resistance coupled with the absence of clear guidance from regulatory bodies further retard acceptance of CDSS. While challenges to develop and deploy CDSS are substantial, the clinical, quality, and economic impacts warrant the effort, especially in disciplines requiring complex decision-making, such as critical and surgical care. Improving diagnosis in health care

  10. Oxygen transport through soft contact lens and cornea: Lens characterization and metabolic modeling

    Science.gov (United States)

    Chhabra, Mahendra

    The human cornea requires oxygen to sustain metabolic processes critical for its normal functioning. Any restriction to corneal oxygen supply from the external environment (e.g., by wearing a low oxygen-permeability contact lens) can lead to hypoxia, which may cause corneal edema (swelling), limbal hyperemia, neovascularization, and corneal acidosis. The need for adequate oxygen to the cornea is a major driving force for research and development of hypertransmissible soft contact lenses (SCLs). Currently, there is no standard technique for measuring oxygen permeability (Dk) of hypertransmissible silicone-hydrogel SCLs. In this work, an electrochemistry-based polarographic apparatus was designed, built, and operated to measure oxygen permeability in hypertransmissible SCLs. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, this apparatus requires only a single lens thickness. The single-lens permeameter provides a reliable, efficient, and economic tool for measuring oxygen permeabilities of commercial hypertransmissible SCLs. The single-lens permeameter measures not only the product Dk, but, following modification, it measures separately diffusivity, D, and solubility, k, of oxygen in hypertransmissible SCLs. These properties are critical for designing better lens materials that ensure sufficient oxygen supply to the cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment, Thus, estimation of the in-vivo corneal oxygen consumption rate is essential for gauging adequate oxygen supply to the cornea. Therefore, we have developed an unsteady-state reactive-diffusion model for the cornea-contact-lens system to determine in-vivo human corneal oxygen-consumption rate. Finally, a metabolic model was developed to determine the relation between contact-lens oxygen transmissibility (Dk/L) and corneal oxygen deficiency. A

  11. Design and analysis of an adaptive lens that mimics the performance of the crystalline lens in the human eye

    Science.gov (United States)

    Santiago-Alvarado, Agustin; Cruz-Félix, Angel S.; Iturbide-Jiménez, F.; Martínez-López, M.; Ramírez-Como, M.; Armengol-Cruz, V.; Vásquez-Báez, I.

    2014-09-01

    Tunable lenses are optical systems that have attracted much attention due to their potential applications in such areas like ophthalmology, machine vision, microscopy and laser processing. In recent years we have been working in the analysis and performance of a liquid-filled variable focal length lens, this is a lens that can modify its focal length by changing the amount of water within it. Nowadays we extend our study to a particular adaptive lens known as solid elastic lens (SEL) that it is formed by an elastic main body made of Polydimethylsiloxane (PDMS Sylgard 184). In this work, we present the design, simulation and analysis of an adaptive solid elastic lens that in principle imitates the accommodation process of the crystalline lens in the human eye. For this work, we have adopted the parameters of the schematic eye model developed in 1985 by Navarro et al.; this model represents the anatomy of the eye as close as possible to reality by predicting an acceptable and accurate quantity of spherical and chromatic aberrations without any shape fitting. An opto-mechanical analysis of the accommodation process of the adaptive lens is presented, by simulating a certain amount of radial force applied onto the SEL using the finite element method with the commercial software SolidWorks®. We also present ray-trace diagrams of the simulated compression process of the adaptive lens using the commercial software OSLO®.

  12. Contact lens correction of presbyopia.

    Science.gov (United States)

    Morgan, Philip B; Efron, Nathan

    2009-08-01

    The ageing population highlights the need to provide effective optical solutions for presbyopic contact lens wearers. However, data gathered from annual contact lens fitting surveys demonstrate that fewer than 40% of contact lens wearers over 45 years of age (virtually all of whom can be presumed to suffer a partial or complete loss of accommodation) are prescribed a presbyopic correction. Furthermore, monovision is prescribed as frequently as multifocal lenses. These observations suggest that an optimal solution to the contact lens correction of presbyopia remains elusive.

  13. Novel Scanning Lens Instrument for Evaluating Fresnel Lens Performance: Equipment Development and Initial Results (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Herrero, R.; Miller, D. C.; Kurtz, S. R.; Anton, I.; Sala, G.

    2013-07-01

    A system dedicated to the optical transmittance characterization of Fresnel lenses has been developed at NREL, in collaboration with the UPM. The system quantifies the optical efficiency of the lens by generating a performance map. The shape of the focused spot may also be analyzed to understand change in the lens performance. The primary instrument components (lasers and CCD detector) have been characterized to confirm their capability for performing optical transmittance measurements. Measurements performed on SoG and PMMA lenses subject to a variety of indoor conditions (e.g., UV and damp heat) identified differences in the optical efficiency of the evaluated lenses, demonstrating the ability of the Scanning Lens Instrument (SLI) to distinguish between the aged lenses.

  14. Synthesis of lens capsule in long-term culture of human lens epithelial cells.

    Science.gov (United States)

    Arita, T; Murata, Y; Lin, L R; Tsuji, T; Reddy, V N

    1993-02-01

    This study examined the extent to which human lens epithelial (HLE) cells in tissue culture retain the potential for differentiation, expression of lens-specific marker proteins, and the synthesis of lens capsule, the major characteristics of lens epithelium in vivo. Primary cultures of HLE cells were maintained for up to 450 days. Transmission and immunoelectron microscopy were used to study the thickness of the synthesized capsule and the formation of type IV collagen and laminin, two major protein components of the basement membrane of lens capsule in vivo. In a long-term HLE culture system, without subcloning, lens fiber differentiation and capsular synthesis were maintained over a period of 450 days. In these cultures, the cell sheet showed three distinct zones: (1) a central zone with tight monolayer; (2) a mild peripheral zone with irregularly aggregated multilayer; and (3) a peripheral zone with loose monolayer. The basement membrane-like material was synthesized in the central zone and lentoids, which serve as a model for fiber differentiation, developed primarily in the mid peripheral zone. No capsular material or lentoids were observed in the peripheral zone. The capsule-like material was 2 to 2.5 microns thick and showed the presence of type IV collagen and laminin, as detected by antibody reaction. This study demonstrates for the first time that HLE cells in long-term cultures synthesize a continuous sheet of capsule-like material. The findings also suggest that reformation of a tight cell-to-cell relationship or generation of high cell density similar to that found in vivo may be an important factor for the synthesis of lens capsule.

  15. The Effects of Maternal Under-Nutrition and a Post-Natal High Fat Diet on Lens Growth, Transparency and Oxidative Defense Systems in Rat Offspring.

    Science.gov (United States)

    Jayaratne, Sachini K; Donaldson, Paul J; Vickers, Mark H; Lim, Julie C

    2017-04-01

    A poor early life nutrition environment is well established to result in a range of cardiometabolic disorders in offspring in later life. These effects can be exacerbated via exposure to an obesogenic dietary environment. To date, the effect of maternal diet and/or a post-natal obesogenic nutritional environment on key characteristics related to lens growth and oxidative stress has not been undertaken. The present study, therefore, examined the characteristics and oxidative status of the lens. Using a model of moderate maternal under-nutrition, rat dams were fed either a control diet (100% ad libitum, CON) or undernourished throughout pregnancy (50% of ad libitum intake, UN) and offspring fed either a control (5% fat, C) or high fat (30% fat, HF) diet post-weaning, resulting in four nutritional groups; CON-C, CON-HF, UN-C, and UN-HF. Offspring lenses were extracted at 160 days of age, weighed, imaged under dark and bright field microscopy, and then dissected into cortical and core fractions for biochemical analyses of oxidative stress markers. Our findings reveal that lenses from all groups were transparent. However, gender specific changes were evident at the biochemical level with increased oxidative stress detected in the cortex and core of female but not male UN-C lenses, and in the cortex of male but not female CON-HF lenses. The greatest increase in oxidative stress was detected in the UN-HF group in the cortex and core regions of the lens and for both genders. These findings show that oxidative stress is exacerbated in the lens as a result of a combination of altered pre-natal and post-natal diet. This demonstrates a novel interaction between the two developmental windows and warrants further investigations toward devising appropriate nutritional strategies for minimizing oxidative stress in the lens.

  16. TU-E-201-01: Methods for Eye Lens Dosimetry and Studies On Lens Opacities with Interventionists

    Energy Technology Data Exchange (ETDEWEB)

    Rehani, M. [Massachusetts General Hospital (United States)

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  17. TU-E-201-03: Eye Lens Dosimetry in Radiotherapy Using Contact Lens-Shaped Applicator

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. [Seoul National University Hospital (Korea, Republic of)

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  18. A review of recent progress in lens-free imaging and sensing.

    Science.gov (United States)

    Roy, Mohendra; Seo, Dongmin; Oh, Sangwoo; Yang, Ji-Woon; Seo, Sungkyu

    2017-02-15

    Recently, lens-free imaging has evolved as an alternative imaging technology. The key advantages of this technology, including simplicity, compactness, low cost, and flexibility of integration with other components, have facilitated the realization of many innovative applications, especially, in the fields of the on-chip lens-free imaging and sensing. In this review, we discuss the development of lens-free imaging, from theory to applications. This article includes the working principle of lens-free digital inline holography (DIH) with coherent and semi coherent light, on-chip lens-free fluorescence imaging and sensing, lens-free on-chip tomography, lens-free on-chip gigapixel nanoscopy, detection of nanoparticles using on-chip microscopy, wide field microscopy, and lens-free shadow image based point-of-care systems. Additionally, this review also discusses the lens-free fluorescent imaging and its dependence on structure and optical design, the advantage of using the compact lens-free driven equilibrium Fourier transform (DEFT) resolved imaging technique for on-chip tomography, the pixel super-resolved algorithm for gigapixel imaging, and the lens-free technology for point-of-care applications. All these low-cost, compact, and fast-processing lens-free imaging and sensing techniques may play a crucial role especially in the fields of environmental, pharmaceutical, biological, and clinical applications of the resource-limited settings. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The 2014 IODC lens design problem: the Cinderella lens

    Science.gov (United States)

    Juergens, Richard C.

    2014-12-01

    The lens design problem for the 2014 IODC is to design a 100 mm focal length lens in which all the components of the lens can be manufactured from ten Schott N-BK7 lens blanks 100 mm in diameter x 30 mm thick. The lens is used monochromatically at 587.56 nm. The goal of the problem is to maximize the product of the entrance pupil diameter and the semi-field of view while holding the RMS wavefront error to <= 0.070 wave within the field of view. There were 45 entries from 13 different countries. Four different commercial lens design programs were used, along with six custom, in-house programs. The number of lens elements in the entries ranged from 10 to 52. The winning entry from Jon Ehrmann had 25 lens elements, and had an entrance pupil diameter of 33.9 mm and a semi-field of view of 62.5° for a merit function product of 2,119.

  20. Detecting an extended light source through a lens

    Energy Technology Data Exchange (ETDEWEB)

    Litaker, E T; Machacek, J R; Gay, T J, E-mail: elitaker2@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0299 (United States)

    2011-07-15

    We present a Monte Carlo simulation of a cylindrical luminescent volume and a typical lens-detector system. The results of this simulation yield a graphically simple picture of the regions within the cylindrical volume from which this system detects light. Because the cylindrical volume permits large angles of incidence, we use a modification of the thin-lens approximation for ray tracing. We compare simulation results with concepts from imaging optics, and comment on implications for experimental design.

  1. Dual focus polarisation splitting lens.

    Science.gov (United States)

    Moseley, Paul; Savini, Giorgio; Zhang, Jin; Ade, Peter

    2017-10-16

    We have successfully designed and measured a unique polarisation splitting lens which focuses the orthogonal linear polarisations side-by-side in the lens focal plane. This concept can find application in situations where there is limited space for the beam splitters and focusing optics that are required for incoherent detectors.

  2. Focusing on Contact Lens Safety

    Science.gov (United States)

    ... these solutions require special care. Always remove contact lenses before swimming. Never reuse any lens solution. Always discard all of the used solution after each use, and add fresh solution to your lens case. Do not expose your contacts to any water (which includes lake, pond, and ocean water as ...

  3. Criteria for choosing lens implants.

    Science.gov (United States)

    Rado, G; Filip, M; Costea, J; Niculescu, C; Pienaru, M

    1998-01-01

    Choosing the proper artificial lens can be a problem, especially for the young surgeons, considering the fact that the "market" is so rich in possibilities. The present paper analyses the lens according to their dimension, form and material, in a perspective based on personal experience.

  4. Prospective, randomized comparison of the use of FloShield Air System® versus the reference technique (water + povidone-iodine solution) during gynecologic endoscopic surgery to evaluate the operative lens vision quality.

    Science.gov (United States)

    Bendifallah, S; Salakos, E; Naoura, I; Aristizabal, P; Furet, E; Zilberman, S; Ballester, M; Darai, E

    2017-06-22

    The FloShield Air System® is a new device for laparoscopic surgery that utilizes a continuous dry CO2 gas flow over the scope to defog the lens and protect it from condensation, debris and smoke. We set out to compare the performance and efficiency of the device in terms of operative lens vision quality (OLVQ) with the reference technique (water + povidone-iodine (PVI) solution) during gynecologic laparoscopic surgery. We conducted a single-center randomized prospective study between March and June 2016 (Trials Database Registration NCT02702531) including 53 patients undergoing gynecologic laparoscopic surgery with water + PVI solution and 51 patients who underwent surgical procedures with the FloShield Air System. The primary outcome measure was the number of laparoscope removals during surgery. Secondary outcome measures were the time to clean, assessment of the quality of vision, the correlation between the laparoscopic surgical complexity and outcomes, and cost effectiveness. Overall, the mean patient age was 43.2 years (range 22-86) and body mass index 24.8 (range 16.8-42.7). The mean number of endoscope removals during surgery was 7.0 (range 0-37) in the water + PVI solution arm and 2.8 (range 0-12) in the FloShield Air System® arm. The number of removals was significantly lower in the FloShield arm (p quality of vision, level of laparoscopic procedure complexity, or cost was observed between the groups. The FloShield Air System® resulted in fewer laparoscopic lens removals than the water + PVI solution solution, but that there was no difference in quality of vision, cleaning time or cost, especially for the more complex surgery.

  5. Lens dislocation has a possible relationship with laser iridotomy

    Directory of Open Access Journals (Sweden)

    Mutoh T

    2012-12-01

    Full Text Available Tetsuya Mutoh,1,2 Kevin F Barrette,2 Yukihiro Matsumoto,1 Makoto Chikuda11Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya City, Saitama, Japan; 2Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USAAbstract: We report our recent experience of four eyes with spontaneous lens dislocation in four patients with no history of trauma or any systemic disease associated with zonular dialysis. Lens dislocation developed with 0.5 to 6 months following laser iridotomy. All patients were male and two eyes were complicated with acute primary angle closure glaucoma preoperatively. Case 1 showed bilateral lens dislocation, while cases 2 and 3 involved unilateral lens dislocation. Cases 2 and 3 showed lenses completely dislocated into the vitreous cavity. All cases needed lens removal and scleral fixation of intraocular lenses. Final visual acuity was 1.2 in all cases. We suspect that laser iridotomy may induce localized zonular dialysis that results in progressive zonular weakness, leading to lens dislocation.Keywords: lens dislocation, laser iridotomy, primary angle closure glaucoma

  6. Contact lens surface changes after exposure to surfactant and abrasive cleaning procedures.

    Science.gov (United States)

    Doell, G B; Palombi, D L; Egan, D J; Huff, J W

    1986-06-01

    Proper lens maintenance is required if contact lens wear is to be successful. Poor compliance or inadequate cleaning may lead to contact lens failures and potentially damage to the eye. With phase contrast microscopy, we addressed the effect of cleaning systems on the physical integrity of a surface-modified lens--the Silcon contact lens. Several cleaners were evaluated for their ability to clean Silcon lenses with minimal damage to the lens surface. The data demonstrated that: all cleaning techniques alter the surface appearance; scratches develop more readily on lenses received with surface irregularities; wettability does not correlate with the extent of surface scratching; recommended cleaning procedures do not directly alter the wettability of the contact lens material; and phase contrast microscopy may be a useful addition to laboratory quality control.

  7. Temporal properties of the lens eyes of the box jellyfish Tripedalia cystophora.

    Science.gov (United States)

    O'Connor, Megan; Nilsson, Dan-E; Garm, Anders

    2010-03-01

    Box jellyfish (Cubomedusae) are visually orientating animals which possess a total of 24 eyes of 4 morphological types; 2 pigment cup eyes (pit eye and slit eye) and 2 lens eyes [upper lens-eye (ule) and lower lens-eye (lle)]. In this study, we use electroretinograms (ERGs) to explore temporal properties of the two lens eyes. We find that the ERG of both lens eyes are complex and using sinusoidal flicker stimuli we find that both lens eyes have slow temporal resolution. The average flicker fusion frequency (FFF) was found to be approximately 10 Hz for the ule and 8 Hz for the lle. Differences in the FFF and response patterns between the two lens eyes suggest that the ule and lle filter information differently in the temporal domain and thus are tuned to perform different visual tasks. The data collected in this study support the idea that the visual system of box jellyfish is a collection of special purpose eyes.

  8. Intraocular lens implantation in microphthalmic patients.

    Science.gov (United States)

    Sinskey, R M; Amin, P; Stoppel, J

    1992-09-01

    Microphthalmos is a developmental disorder of the eye consisting of a smaller than normal eye. This disorder can present as an isolated condition or associated with other systemic alterations. It is not uncommon for patients with microphthalmos to have congenital cataracts along with other ocular and systemic abnormalities. This paper reports the experience with 11 microphthalmic eyes of seven patients who had primary or secondary intraocular lens (IOL) implantation over a six-year period from 1985 to 1991. In all cases the IOL had a 13.5 mm or 14.0 mm overall diameter and a 6.0 mm or 6.5 mm optic. It was difficult to obtain documentation of objective visual improvement in many of these cases because of the associated nystagmus. However, all patients reported subjective improvements. These results suggest that with proper technique and lens selection microphthalmic patients should be considered for IOL implantation with relative safety and success.

  9. Wedged multilayer Laue lens

    Science.gov (United States)

    Conley, Ray; Liu, Chian; Qian, Jun; Kewish, Cameron M.; Macrander, Albert T.; Yan, Hanfei; Kang, Hyon Chol; Maser, Jörg; Stephenson, G. Brian

    2008-05-01

    A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

  10. Imaging the mass structure of distant lens galaxies

    Science.gov (United States)

    Koopmans, Leon

    2005-07-01

    The surface brightness distribution of extended gravitationally lensed arcs and Einstein rings contains super-resolved information about the lensed object, and, more excitingly, about the smooth and clumpy mass distribution of the lens galaxies. The source and lens information can non-parametrically be separated, resulting in a direct "gravitational-mass image" of the inner mass-distribution of cosmologically-distant galaxies {Koopmans 2005}.With this goal in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W imaging of 15 gravitational-lens systems with spatially resolved lensed sources, selected from the 17 new lens systems discovered by the Sloan Lens ACS Survey {Bolton et al. 2004}. Each system has been selected from the SDSS and confirmed in a time-efficient HST-ACS snapshot program {cycle-13}; they show highly-magnified arcs or Einstein rings, lensed by a massive early-type lens galaxy. High-fidelity multi-color HST images are required {not delivered by the 420-sec snapshot images} to isolate these lensed images {properly cleaned, dithered and extinction-corrected} from the lens galaxy surface brightness distribution, and apply our "gravitational-mass imaging" technique.The sample of galaxy mass distributions - determined through this method from the arcs and Einstein ring HST images - will be studied to: {i} measure the smooth mass distribution of the lens galaxies {Dark and luminous mass are separated using the HST images and the stellar M/L values derived from a joint stellar-dynamical analysis of each system}; {ii} quantify statistically and individually the incidence of mass-substructure {with or without obvious luminous counter-parts such as dwarf galaxies}. Since dark-matter substructure should be considerably more prevalent at higher redshift, both results provide a direct test of this prediction of the CDM hierarchical structure-formation model.

  11. Microelectrofluidic lens for variable curvature

    Science.gov (United States)

    Chang, Jong-hyeon; Lee, Eunsung; Jung, Kyu-Dong; Lee, Seungwan; Choi, Minseog; Kim, Woonbae

    2012-10-01

    This paper presents a tunable liquid lens based on microelectrofluidic technology which integrates electrowetting and microfluidics. In the novel microelectrofluidic lens (MEFL), electrowetting in the hydrophobic surface channel induces the Laplace pressure difference between two fluidic interfaces on the lens aperture and the surface channel. Then, the pressure difference makes the lens curvature tunable. The previous electrowetting lens in which the contact angle changes at the side wall has a certain limitation of the curvature variation because of the contact angle saturation. Although the contact angle saturation also appears in the surface channel of the MEFL, the low surface channel increases the Laplace pressure and it makes the MEFL to have full variation of the optical power possible. The magnitude of the applied voltage determines the lens curvature in the analog mode MEFL as well as the electrowetting lens. Digital operation is also possible when the control electrodes of the MEFL are patterned to have an array. It is expected that the proposed MEFL is able to be widely used because of its full variation of the optical power without the use of oil and digital operation with fast response.

  12. Extend focal depth of a tracking lens by phase apodizers

    Science.gov (United States)

    Cai, Xianyang; Chang, Shoude; Flueraru, Costel

    2005-09-01

    In a conventional particle tracking system, the depth of field is usually very small because of the use of high power imaging lens. The tracking accuracy may also be affected by the smearing of spot image, caused by focal shift. Increasing the focal depth and keeping uniform spot size in the focal region is highly desirable for a high accurate tracking system. In this report, we study the design of phase apdodizer that could be used to increase the focal depth of a tracking lens. The design is based on the requirements by highly accurate tracking that the point-spread function (PSF) of the lens keep an even and concentrated energy distribution when the lens is defocused. To achieve this purpose, a pure phase-shifting apodizer is introduced on the pupil plane of the lens. The function of the apodizer is to control the energy distribution of the 3D diffraction pattern near the focal region and make the effective spot size uniform or minimum variation along optical axis. The pattern of the 3D PSF of the lens with the apodizer shapes closed to a cylinder. New method used to search and optimize the design of the phase apodizer that meet the requirements of a particle tracking system will be studied. Theoretical analysis and numerical simulation are given in support of the method.

  13. Chitah: Strong-gravitational-lens hunter in imaging surveys

    Energy Technology Data Exchange (ETDEWEB)

    Chan, James H. H.; Suyu, Sherry H.; Chiueh, Tzihong; More, Anupreeta; Marshall, Philip J.; Coupon, Jean; Oguri, Masamune; Price, Paul

    2015-07-07

    Strong gravitationally lensed quasars provide powerful means to study galaxy evolution and cosmology. Current and upcoming imaging surveys will contain thousands of new lensed quasars, augmenting the existing sample by at least two orders of magnitude. To find such lens systems, we built a robot, Chitah, that hunts for lensed quasars by modeling the configuration of the multiple quasar images. Specifically, given an image of an object that might be a lensed quasar, Chitah first disentangles the light from the supposed lens galaxy and the light from the multiple quasar images based on color information. A simple rule is designed to categorize the given object as a potential four-image (quad) or two-image (double) lensed quasar system. The configuration of the identified quasar images is subsequently modeled to classify whether the object is a lensed quasar system. We test the performance of Chitah using simulated lens systems based on the Canada–France–Hawaii Telescope Legacy Survey. For bright quads with large image separations (with Einstein radius ${r}_{\\mathrm{ein}}\\gt 1\\buildrel{\\prime\\prime}\\over{.} 1$) simulated using Gaussian point-spread functions, a high true-positive rate (TPR) of $\\sim 90\\%$ and a low false-positive rate of $\\sim 3\\%$ show that this is a promising approach to search for new lens systems. We obtain high TPR for lens systems with ${r}_{\\mathrm{ein}}\\gtrsim 0\\buildrel{\\prime\\prime}\\over{.} 5$, so the performance of Chitah is set by the seeing. We further feed a known gravitational lens system, COSMOS 5921+0638, to Chitah, and demonstrate that Chitah is able to classify this real gravitational lens system successfully. Our newly built Chitah is omnivorous and can hunt in any ground-based imaging surveys.

  14. Lens surface roughening for tears invariant contact lens performance

    Science.gov (United States)

    Zalevsky, Zeev; Azogui, Jonathan; Limon, Ofer; Rudnitsky, Arkady

    2014-03-01

    In many extended depth of focus diffractive or interferometry based ophthalmic contact lenses the time varied tears layers affect the ophthalmic functionality of the lens. In this paper we present a new approach involving nano pillars realized inside the grooves of a contact lens aiming to implement any type of extended depth of focus or diffractive optical element for ophthalmic applications in order to solve the micro fluidics layer uncertainty within the micro sag features.

  15. Contact Allergy To Hard Contact Lens

    Directory of Open Access Journals (Sweden)

    J S Pasricha

    1985-01-01

    Full Text Available Three patients developed recurrent irritation, redness and watery discharge from their eyes after using hard contact lens. Patch tests were positive with the material of the hard contact lens and negative with teepol, sodium lauryl sulphate and material of the soft contact lens. All the three patients became alright after they stopped,using hard contact lens.

  16. Epidemiology of contact lens-induced infiltrates: an updated review.

    Science.gov (United States)

    Steele, Kelsy R; Szczotka-Flynn, Loretta

    2017-09-01

    Corneal infiltrative events (CIEs) are well established as a risk associated with soft contact lens wear. The incidence of symptomatic CIEs during extended soft lens wear ranges from 2.5 to six per cent; when asymptomatic CIEs are included, the incidence can be as high as 20-25 per cent. In daily soft lens wear, the annual incidence of symptomatic CIEs is about three per cent. There are various accepted methods of categorising CIEs, and a scoring system based on clinical signs and symptoms is a good approach to grade severity. Lens-related risk factors include extended wear, silicone hydrogel material, the use of multipurpose solutions, bacterial bioburden and reusable lenses. Recent studies report that daily disposable lenses reduce the risk of CIEs. © 2017 Optometry Australia.

  17. Lens cytoskeleton and after-cataract.

    Science.gov (United States)

    Rafferty, N S; Rafferty, K A

    1992-01-01

    Lens epithelial and other ocular cells contain complex arrays of actin filaments which might be expected to allow them to migrate following injury: specifically into the capsular sac in cases of extracapsular cataract extraction or traumatic cataract. To test the possibility, a culture system was developed using a melanotic strain of mice, in which migrating cells are often 'marked' by melanosomes. Injured lenses were cultured on permeable membranes in contact with nutrient medium, and surrounded by iridial tract fragments. After study by light and electron microscopy, it was established that both pigmented and unpigmented cells migrated from the surrounding explants, apparently along the substrate meniscus, to the outside of the lens capsule and then through the wound to the capsule interior. This study suggests a source of cells in development of after-cataract syndrome.

  18. Pulser for the Tevatron electron lens gun

    Energy Technology Data Exchange (ETDEWEB)

    Iouri Terechkine et al.

    2004-05-18

    To compensate for beam-beam interaction in Tevatron, an ''electron lens'' is considered to be an effective instrument. When a bunch of electrons with energy in the range (10-16) kV is overlapping with a bunch of antiprotons, the resulting focusing force for antiprotons can be adjusted by changing the electron beam current and by profiling its radial distribution. There exist several scenarios of how the system must function. According to one of them, an electron gun that supplies electrons must be fed by voltage pulses that follow with the frequency of antiproton bunches circulating in the Tevatron, which is about 2.5 MHz. To provide focusing tailored for each individual antiproton bunch, a modulator of the gun (pulser) must allow pulse-to-pulse voltage change. This report will cover main approaches to a design of a pulser for use with the gun of the Tevatron Electron Lens.

  19. Understanding eating interventions through an evolutionary lens.

    Science.gov (United States)

    Ahlstrom, Britt; Dinh, Tran; Haselton, Martie G; Tomiyama, A Janet

    2017-03-01

    Health psychologists aim to improve eating behaviour to achieve health. Yet the effectiveness of healthy eating interventions is often minimal. This ineffectiveness may be in part because many healthy eating interventions are in a battle against evolved mechanisms (e.g., hedonic and related systems) that promote the consumption of energy-dense foods. Such foods, once rare, are now abundant in our obesogenic society, and consequently the evolved desire for energy-dense foods can now easily lead to the overconsumption of sugary, processed, and unhealthy foods. However, humans have other evolved mechanisms that also impact eating behaviour. In this article, therefore, we review eating interventions through an evolutionary lens, and describe evolved mechanisms that are relevant to eating behaviour. We discuss how using this lens could help health psychologists design more effective eating interventions and policies. By learning to work with human nature, eating interventions can more effectively promote healthier eating and healthier lives.

  20. Adaptive Liquid Lens Actuated by Droplet Movement

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2014-08-01

    Full Text Available In this paper we report an adaptive liquid lens actuated by droplet movement. Four rectangular PMMA (Polymethyl Methacrylate substrates are stacked to form the device structure. Two ITO (Indium Tin Oxide sheets stick on the bottom substrate. One PMMA sheet with a light hole is inserted in the middle of the device. A conductive droplet is placed on the substrate and touches the PMMA sheet to form a small closed reservoir. The reservoir is filled with another immiscible non-conductive liquid. The non-conductive liquid can form a smooth concave interface with the light hole. When the device is applied with voltage, the droplet stretches towards the reservoir. The volume of the reservoir reduces, changing the curvature of the interface. The device can thus achieve the function of an adaptive lens. Our experiments show that the focal length can be varied from −10 to −159 mm as the applied voltage changes from 0 to 65 V. The response time of the liquid lens is ~75 ms. The proposed device has potential applications in many fields such as information displays, imaging systems, and laser scanning systems.

  1. A Prototype Antifungal Contact Lens

    OpenAIRE

    Ciolino, Joseph B; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.; Kohane, Daniel S.

    2011-01-01

    Econazole-eluting contact lenses with a novel design provided extended antifungal activity against the Candida albicans fungus. This drug-eluting contact lens could be used to treat and prevent fungal ocular infections.

  2. Cataract mutations and lens development.

    Science.gov (United States)

    Graw, J

    1999-03-01

    The lens plays an essential role for proper eye development. Mouse mutants affecting lens development are excellent models for corresponding human disorders. Moreover, using mutations in particular genes the process of eye and lens development can be dissected into distinct steps. Therefore, three mouse mutants will be described in detail and discussed affecting three essential stages: formation of the lens vesicle, initiation of secondary lens fiber cell formation, and terminal differentiation of the secondary fiber cells. The mutant aphakia (ak) has been characterized by bilaterally apakic eyes [Varnum and Stevens (1968) J. Hered. 59, 147-150], and the corresponding gene was mapped to chromosome 19 [Varnum and Stevens (1975) Mouse News Letters 53, 35]. Recent investigations in our laboratory refined the linkage 0.6 +/- 0.3 N cm proximal to the microsatellite marker D19Mit10. The linked gene Pax2, responsible for proper development of the posterior part of the eye and the optic nerve, was excluded as candidate gene by sequence analysis. Histological analysis of the homozygous ak mutants revealed a persisting lens stalk and subsequently the formation of lens rudiments. The lens defects led to irregular iris development and retinal folding. Congenital aphakia is known as a rare human anomaly. Besides a corneal dystrophy (CDTB), no corresponding disease is localized at the homologous region of human chromosome 10q23. The Cat3 mutations are characterized by vacuolated lenses caused by alterations in the beginning of secondary lens fiber cell differentiation at embryonic day 12.5. Secondary malformations develop at the cornea and the iris, but the retina remains unaffected. Two mutant alleles of the Cat3 locus have been mapped to mouse chromosome 10 very close to the microsatellite markers D10Mit41 and D10Mit95 (less than 0.3 cM). Since Cat3 is mapped to a position, which is homologous to human chromosome 12q21-24, the disorder cornea plana congenita can be considered

  3. The pupil can control an artificial lens intuitively.

    Science.gov (United States)

    Fliedner, Jan; Heine, Christian; Bretthauer, Georg; Wilhelm, Helmut

    2014-02-04

    After cataract surgery, the ability to accommodate is lost. For this reason, a mechatronic IOL is being developed at the moment: The Artificial Accommodation System. This device requires an easily measureable indicator of the distance of the observed object to determine the demand of accommodation. As the pupil constricts with near vision, pupil size might be such an indicator. Our research focused on whether the pupil can control an artificial lens. A study with 14 healthy subjects aged between 24 and 64 years was conducted. An artificial lens with variable refractive power was mounted in front of one eye. In this eye, natural accommodation was greatly reduced or absent due to presbyopia, pseudophakia, or iatrogenic cycloplegia. The lens' refractive power was changed in a computer-controlled manner depending on changes in the pupil diameter of the second eye, which could not see the fixation stimulus. The subject's task was to get a clear focused image of the target in different distances. The lens can be controlled by the pupil intuitively (P < 1.8 × 10(-18)). Without prior knowledge, 11/14 subjects passed the first trial, and 31/41 trials were successful. Only one subject was not able to control the lens at all. Most subjects comprehended instantly how to use the unfamiliar lens control to bring a target into focus. This study emphasizes the plasticity of the visual control system. Positioning accuracy was acceptable, but the control must be optimized to facilitate maintaining a defined refractive power.

  4. Single lens laser beam shaper

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  5. Aggregation and fibrillation of eye lens crystallins by homocysteinylation; implication in the eye pathological disorders.

    Science.gov (United States)

    Khazaei, Sima; Yousefi, Reza; Alavian-Mehr, Mohammad-Mehdi

    2012-12-01

    There are several evidences, suggesting a relationship between hyperhomocysteinemia and various diseases of the visual system. Therefore in this study the effects of homocysteinylation on aggregation and fibrillation of lens crystallins were studied using spectroscopic techniques, SDS-PAGE and western blot analysis. The results of UV-Vis absorption studies suggest an induction of lens protein aggregation after homocysteinylation. Furthermore, the existence of fibril in the aggregate of lens proteins confirmed by Congo red absorption measurement and Thioflavin-T fluorescence assay. Taken together the results of SDS-PAGE and Western blotting, it is suggested that almost all detectable eye lens crystallins are prone to aggregation by homocysteinylation, while α-Crystallin comprises the main portion of lens protein aggregate. Overall this study may suggest lens protein homocysteinylation as a possible mechanism to explain the relationship between hyperhomocysteinimia and some impairments of the visual system.

  6. Laboratory Demonstration of Axicon-Lens Coronagraph

    Science.gov (United States)

    Choi, Jaeho; Jea, Geonho

    2018-01-01

    The results of laboratory based experiments of the proposed coronagraph using axicon-lenses that is conjunction with a method of noninterferometric quantitative phase imaging for direct imaging of exoplanets is will present. The light source is passing through tiny holes drilled on the thin metal plate is used as the simulated stellar and its companions. Those diffracted light at the edge of the holes bears a similarity to the light from the bright stellar. Those images are evaginated about the optical axis after the maximum focal length of the first axicon lens. Then the evaginated images of have cut off using the motorized iris which means the suppressed the central stellar light preferentially. Various length between the holes which represent the angular distance are examined. The laboratory experimental results are shown that the axicon-lens coronagraph has feature of ability to achieve the smaller IWA than l/D and high-contrast direct imaging. The laboratory based axicon-lens coronagraph imaging support the symbolic computation results which has potential in direct imaging for finding exoplanet and various astrophysical activities. The setup of the coronagraph is simple to build and is durable to operate. Moreover it can be transported the planets images to a broadband spectrometric instrument that able to investigate the constituent of the planetary system.

  7. CYLINDER LENS ALIGNMENT IN THE LTP

    Energy Technology Data Exchange (ETDEWEB)

    TAKACS, P.Z.

    2005-07-26

    The Long Trace Profiler (LTP), is well-suited for the measurement of the axial figure of cylindrical mirrors that usually have a long radius of curvature in the axial direction but have a short radius of curvature in the sagittal direction. The sagittal curvature causes the probe beam to diverge in the transverse direction without coming to a focus on the detector, resulting in a very weak signal. It is useful to place a cylinder lens into the optical system above the mirror under test to refocus the sagittal divergence and increase the signal level. A positive cylinder lens can be placed at two positions above the surface: the Cat's Eye reflection position and the Wavefront-Matching position. The Cat's Eye position, is very tolerant to mirror misalignment, which is not good if absolute axial radius of curvature is to be measured. Lateral positioning and rotational misalignments of lens and the mirror combine to produce unusual profile results. This paper looks at various alignment issues with measurements and by raytrace simulations to determine the best strategy to minimize radius of curvature errors in the measurement of cylindrical aspheres.

  8. Primate lens capsule elasticity assessed using Atomic Force Microscopy

    Science.gov (United States)

    Ziebarth, Noël M.; Arrieta, Esdras; Feuer, William J.; Moy, Vincent T.; Manns, Fabrice; Parel, Jean-Marie

    2011-01-01

    The purpose of this project is to measure the elasticity of the human and non-human primate lens capsule at the microscopic scale using Atomic Force Microscopy (AFM). Elasticity measurements were performed using AFM on the excised anterior lens capsule from 9 cynomolgus monkey (5.9–8.0 years), 8 hamadryas baboon (2.8–10.1 years), and 18 human lenses (33–79 years). Anterior capsule specimens were obtained by performing a 5mm continuous curvilinear capsulorhexis and collecting the resulting disk of capsular tissue. To remove the lens epithelial cells the specimen was soaked in 0.1% trypsin and 0.02% EDTA for five minutes, washed, and placed on a Petri dish and immersed in DMEM. Elasticity measurements of the capsule were performed with a laboratory-built AFM system custom designed for force measurements of ophthalmic tissues. The capsular specimens were probed with an AFM cantilever tip to produce force-indentation curves for each specimen. Young’s modulus was calculated from the force-indentation curves using the model of Sneddon for a conical indenter. Young’s modulus of elasticity was 20.1–131kPa for the human lens capsule, 9.19–117kPa for the cynomolgus lens capsule, and 13.1–62.4kPa for the baboon lens capsule. Young’s modulus increased significantly with age in humans (p=0.03). The age range of the monkey and baboon samples was not sufficient to justify an analysis of age dependence. The capsule elasticity of young humans (<45 years) was not statistically different from that of the monkey and baboon. In humans, there is an increase in lens capsule stiffness at the microscale that could be responsible for an increase in lens capsule bulk stiffness. PMID:21420953

  9. Preliminary investigation of an active PLZT lens

    Science.gov (United States)

    Peters, Bruce R.; Reardon, Patrick J.; Wong, K. J.

    2001-05-01

    The design analysis and preliminary testing of a prototype AFOCL is described. The AFOCL is an active optical component composed of solid state lead lanthanum-modified zirconate titanate (PLZT) ferroelectric ceramic with patterned indium tin oxide (ITO) transparent surface electrodes that modulate the refractive index of the PLZT to function as an electro- optic lens. The AFOCL was developed to perform optical re- alignment and wavefront correction to enhance the performance of Ultra-Lightweight Structures and Space Observatories. The AFOCL would be an active optical component within a larger optical system. Information from a wavefront sensor would be processed to provide input to the AFOCL to drive the sense4d wavefront tot he desired shape and location. While offering variable and rapid focusing capability similar to liquid crystal based spatial light modulators, the AFOCL offers some potential advantages because it is a solid-stat, stationary, low-mass, rugged, and thin optical element that can produce wavefront quality comparable to the solid refractive lens it replaces. The AFOCL acts as a positive or negative lens by producing a parabolic phase-shift in the PLZT material through the application of a controlled voltage potential across the ITO electrodes. To demonstrate the technology, a 4 mm diameter lens was fabricated to produce 5-waves of optical power operating at 2.051 micrometers wavelength. Optical metrology was performed on the device to measure focal length, optical quality, and efficiency for a variety of test configurations. Preliminary data was analyzed and compared to idealized performance available from computer-based models of the AFOCL.

  10. Color waveguide transparent screen using lens array holographic optical element

    Science.gov (United States)

    Liu, Siqi; Sun, Peng; Wang, Chang; Zheng, Zhenrong

    2017-11-01

    A color transparent screen was designed in this paper, a planar glass was used as a waveguide structure and the lens array holographic optical element (HOE) was used as a display unit. The lens array HOE was exposed by two coherent beams. One was the reference wave which directly illuminated on the holographic material and the other was modulated by the micro lens array. The lens array HOE can display the images with see-through abilities. Unlike the conventional lens array HOE, a planar glass was adopted as the waveguide in the experiment. The projecting light was totally internal-reflected in the planar glass to eliminate the undesired zero-order diffracted light. By using waveguide, it also brings advantage of compact structure. Colorful display can be realized in our system as the holographic materials were capable for multi-wavelength display. In this paper, a color transparent screen utilizing the lens array HOE and waveguide were designed. Experiment results showed a circular display area on the transparent screen. The diameter of the area is 20 mm and it achieved the pixel resolution of 100 μm. This simple and effective method could be an alternative in the augment reality (AR) applications, such as transparent phone and television.

  11. Conservation through the economics lens.

    Science.gov (United States)

    Farley, Joshua

    2010-01-01

    Although conservation is an inherently transdisciplinary issue, there is much to be gained from examining the problem through an economics lens. Three benefits of such an approach are laid out in this paper. First, many of the drivers of environmental degradation are economic in origin, and the better we understand them, the better we can conserve ecosystems by reducing degradation. Second, economics offers us a when-to-stop rule, which is equivalent to a when-to-conserve rule. All economic production is based on the transformation of raw materials provided by nature. As the economic system grows in physical size, it necessarily displaces and degrades ecosystems. The marginal benefits of economic growth are diminishing, and the marginal costs of ecological degradation are increasing. Conceptually, we should stop economic growth and focus on conservation when the two are equal. Third, economics can help us understand how to efficiently and justly allocate resources toward conservation, and this paper lays out some basic principles for doing so. Unfortunately, the field of economics is dominated by neoclassical economics, which builds an analytical framework based on questionable assumptions and takes an excessively disciplinary and formalistic approach. Conservation is a complex problem, and analysis from individual disciplinary lenses can make important contributions to conservation only when the resulting insights are synthesized into a coherent vision of the whole. Fortunately, there are a number of emerging transdisciplines, such as ecological economics and environmental management, that are dedicated to this task.

  12. Bifocal liquid lens zoom objective for mobile phone applications

    Science.gov (United States)

    Wippermann, F. C.; Schreiber, P.; Bräuer, A.; Craen, P.

    2007-02-01

    Miniaturized camera systems are an integral part of today's mobile phones which recently possess auto focus functionality. Commercially available solutions without moving parts have been developed using the electrowetting technology. Here, the contact angle of a drop of a conductive or polar liquid placed on an insulating substrate can be influenced by an electric field. Besides the compensation of the axial image shift due to different object distances, mobile phones with zoom functionality are desired as a next evolutionary step. In classical mechanically compensated zoom lenses two independently driven actuators combined with precision guides are needed leading to a delicate, space consuming and expansive opto-mechanical setup. Liquid lens technology based on the electrowetting effect gives the opportunity to built adaptive lenses without moving parts thus simplifying the mechanical setup. However, with the recent commercially available liquid lens products a completely motionless and continuously adaptive zoom system with market relevant optical performance is not feasible. This is due to the limited change in optical power the liquid lenses can provide and the dispersion of the used materials. As an intermediate step towards a continuously adjustable and motionless zoom lens we propose a bifocal system sufficient for toggling between two effective focal lengths without any moving parts. The system has its mechanical counterpart in a bifocal zoom lens where only one lens group has to be moved. In a liquid lens bifocal zoom two groups of adaptable liquid lenses are required for adjusting the effective focal length and keeping the image location constant. In order to overcome the difficulties in achromatizing the lens we propose a sequential image acquisition algorithm. Here, the full color image is obtained from a sequence of monochrome images (red, green, blue) leading to a simplified optical setup.

  13. Enzyme activities in human lens epithelium of age-related cataract.

    Science.gov (United States)

    Belpoliti, M; Maraini, G; Alberti, G; Corona, R; Crateri, S

    1993-09-01

    To investigate associations between enzyme activity of glutathione reductase (GR) with and without added flavin adenine dinucleotide (FAD), glutathione peroxidase (GPX), and 6-phosphogluconic dehydrogenase (6PGDH) in the lens epithelium collected at surgery, and some nutritional and biochemical variables determined in the same individuals during the Italian-American Case-Control Study of age-related cataract. One hundred eighty-three epithelium capsule samples were collected from 174 patients undergoing surgery. Data on enzyme activity were obtained from 52 samples for 6-PGDH and from 53 samples for GR and for GPX. The Lens Opacity Classification System II was used to classify and grade cataracts. No correlation was found between enzyme activity in lens epithelium and the same enzymatic activity in erythrocytes (with the exception of a negative correlation between lens and erythrocyte 6PGDH activity), or the type and severity of cataract. No correlation was found between lens GPX activity and plasma selenium and between lens GR activation coefficient (GRAC) and riboflavin intake. Lens GR with added FAD and lens GRAC were significantly correlated to plasma vitamin E level. Lens GRAC was positively correlated to a nutritional vitamin index. Present data stress the difficulty in verifying the assumption that biochemical indices collected on plasma and on erythrocyte actually reflect the status of these factors in the lens itself.

  14. The edge-on spiral gravitational lens B1600+434

    NARCIS (Netherlands)

    Koopmans, LVE; de Bruyn, AG; Jackson, N

    1998-01-01

    We present new observations of the gravitational lens (GL) system B1600 + 434, strongly suggesting that the lens is an edge-on spiral galaxy. These observations are used to constrain the mass model of the system? in particular the oblateness and velocity dispersion of the dark matter halo around the

  15. Polarization response of RHIC electron lens lattices

    Directory of Open Access Journals (Sweden)

    V. H. Ranjbar

    2016-10-01

    Full Text Available Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. In particular we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. These results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. Finally we consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

  16. Athermal design and analysis of glass-plastic hybrid lens

    Science.gov (United States)

    Yang, Jian; Cen, Zhaofeng; Li, Xiaotong

    2018-01-01

    With the rapid development of security market, the glass-plastic hybrid lens has gradually become a choice for the special requirements like high imaging quality in a wide temperature range and low cost. The reduction of spherical aberration is achieved by using aspherical surface instead of increasing the number of lenses. Obviously, plastic aspherical lens plays a great role in the cost reduction. However, the hybrid lens has a priority issue, which is the large thermal coefficient of expansion of plastic, causing focus shift and seriously affecting the imaging quality, so the hybrid lens is highly sensitive to the change of temperature. To ensure the system operates normally in a wide temperature range, it is necessary to eliminate the influence of temperature on the hybrid lens system. A practical design method named the Athermal Material Map is summarized and verified by an athermal design example according to the design index. It includes the distribution of optical power and selection of glass or plastic. The design result shows that the optical system has excellent imaging quality at a wide temperature range from -20 ° to 70 °. The method of athermal design in this paper has generality which could apply to optical system with plastic aspherical surface.

  17. Hyperchromatic lens for recording time-resolved phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Frayer, Daniel K.

    2017-07-11

    A method and apparatus for the capture of a high number of quasi-continuous effective frames of 2-D data from an event at very short time scales (from less than 10.sup.-12 to more than 10.sup.-8 seconds) is disclosed which allows for short recording windows and effective number of frames. Active illumination, from a chirped laser pulse directed to the event creates a reflection where wavelength is dependent upon time and spatial position is utilized to encode temporal phenomena onto wavelength. A hyperchromatic lens system receives the reflection and maps wavelength onto axial position. An image capture device, such as holography or plenoptic imaging device, captures the resultant focal stack from the hyperchromatic lens system in both spatial (imaging) and longitudinal (temporal) axes. The hyperchromatic lens system incorporates a combination of diffractive and refractive components to maximally separate focal position as a function of wavelength.

  18. Wafer-level fabrication of multi-element glass lenses: lens doublet with improved optical performances.

    Science.gov (United States)

    Albero, Jorge; Perrin, Stéphane; Passilly, Nicolas; Krauter, Johann; Gauthier-Manuel, Ludovic; Froehly, Luc; Lullin, Justine; Bargiel, Sylwester; Osten, Wolfgang; Gorecki, Christophe

    2016-01-01

    This Letter reports on the fabrication of glass lens doublets arranged in arrays and realized at wafer level by means of micro-fabrication. The technique is based on the accurate vertical assembly of separately fabricated glass lens arrays. Since each one of these arrays is obtained by glass melting in silicon cavities, silicon is employed as a spacer in order to build a well-aligned and robust optical module. It is shown that optical performance achieved by the lens doublet is better than for a single lens of equivalent numerical aperture, thanks to lower optical aberrations. The technique has good potential to match the optical requirements of miniature imaging systems.

  19. [Current quality management situation and administration countermeasure study of enterprises marketing corneal contact lens].

    Science.gov (United States)

    Liu, Yungui; Yao, Ying; Shangguan, Shihao; Gu, Qun; Gao, Wuming; Chen, Yaoshui

    2014-05-01

    Study the current quality management situation of enterprises marketing corneal contact lens via systemic investigations and explore effective administration countermeasures in the future. The quality management indicators of sixty-two corneal contact lens marketing enterprises in Xuhui district of Shanghai were systematically investigated and enterprises of different operation models was compared and analyzed. Wholesale enterprises and retail chain enterprises are apparently better than independent enterprises almost in all facets. Facilitate market accession of corneal contact lens marketing enterprises, encourage the business model of retail chain, enhance supervision of corneal contact lens marketing enterprises, especially independent franchisors.

  20. [Contact lens-related keratitis].

    Science.gov (United States)

    Steiber, Zita; Berta, András; Módis, László

    2013-11-10

    Nowadays, keratitis, corneal infection due to wearing contact lens means an increasingly serious problem. Neglected cases may lead to corneal damage that can cause blindness in cases of otherwise healthy eyes. Early diagnosis based on the clinical picture and the typical patient history is an important way of prevention. Prophylaxis is substantial to avoid bacterial and viral infection that is highly essential in this group of diseases. Teaching contact lens wearers the proper contact lens care, storage, sterility, and hygiene regulations is of great importance. In case of corneal inflammation early accurate diagnosis supported by microbiological culture from contact lenses, storage boxes or cornea is very useful. Thereafter, targeted drug therapy or in therapy-resistant cases surgical treatment may even be necessary in order to sustain suitable visual acuity.

  1. A framework of cloud supported collaborative design in glass lens moulds based on aspheric measurement

    Science.gov (United States)

    Zhu, Yongjian; Wang, Yu; Na, Jingxin; Zhi, Yanan; Fan, Yufeng

    2013-09-01

    Aspheric mould design includes the top-down design and reversal design. In this paper, a new framework of reversal design is proposed combining with cloud supported collaborative design (CSCD) based on aspheric measurement. The framework is a kind of collaborative platform, which is composed of eight modules, including the computerized aspheric precision measurement module (CAPM), computer-aided optical design of aspheric lens system (CAOD), computer-aided design of lens mould (CADLM), FEM(finite element method) simulation of lens molding module (FEMLM), computer-aided manufacture of lens and moulds (CAMLM), measurement data analysis module (MDAM), optical product lifecycle management module (OPLM) and cloud computing network module (CCNM). In this framework, the remote clients send an improved requirement or fabrication demand about optical lens system through CCNM, which transfers this signal to OPLM. In OPLM, one main server is in charge of the task distribution and collaborative work of other six modules. The first measurement data of aspheric lens are produced by clients or our proposed platform CAPM, then are sent to CAOD for optimization and the electronic drawings of lens moulds are generated in CADLM module. According the design drawings, the FEMLM could give the lens-molding simulation parameters through FEM software. The simulation data are used for the second design of moulds in CADLM module. In this case, the moulds could be fabricated in CAMLM by ultra-precision machine, and the aspheric lens could be also produced by lens-molding machine in CAMLM. At last, the final shape of aspheric lens could be measured in CAPM and the data analysis could be conducted in MDAM module. Through the proposed framework, all the work described above could be performed coordinately. And the optimum design data of lens mould could be realized and saved, then shared by all the work team.

  2. Contact lens care in keratoconus.

    Science.gov (United States)

    Zhou, Alana J; Kitamura, Keiko; Weissman, Barry A

    2003-12-01

    To quantify the complexity involved in fitting contact lenses on the eyes of patients with keratoconus. The contact lens care of one randomly selected eye each of 38 keratoconus patients was retrospectively analyzed and compared to that of 38 gender and age matched controls. We evaluated the number of diagnostic contact lenses used to establish the initial contact lens order, number of ordered rigid gas permeable (RGP) contact lenses needed to complete the fit, number of office visits during the initial 4 months of care, best spectacle and RGP contact lenses corrected Log MAR visual acuities, complications encountered, and whether or not the patient was successful in contact lens wear. Keratoconic eyes statistically used more diagnostic lenses, more ordered lenses, and more office visits than did normal eyes. Visual acuities improved from an average of 20/40 with spectacles to an average of 20/20 by use of RGP contact lenses in keratoconic eyes. Visions were corrected to 20/20 with both spectacles and contact lenses in control eyes. Sixty nine percent (69%) of keratoconic eyes and 95% of controls were successful in contact lens wear. Contact lens care of keratoconic eyes is more challenging than care of normal eyes because of the need for more diagnostic and ordered contact lenses and the use of more professional time. Keratoconic eyes may suffer more complications than normals during contact lens care, but this does not affect the success rates, and such patients benefit from enhanced visual acuity with RGP contact lenses compared to that achieved with spectacles.

  3. Topological robotics in lens spaces

    Science.gov (United States)

    González, Jesús

    2005-11-01

    Motivated by the work of Farber, Tabachnikov and Yuzvinsky on the motion planning problem for projective spaces, we give an estimate for the topological complexity (TC) of lens spaces in terms of certain generalized “skew” maps between spheres. This last concept turns out to be closely related to that for a generalized axial map developed by Astey, Davis and the author to characterize the smallest Euclidean dimension where (2-torsion) lens spaces can be immersed. As a result, this suggests an alternative simpler “TC-approach” to the classical immersion problem for real projective spaces, whose initial stages we settle by means of techniques in obstruction theory.

  4. 21 CFR 886.3600 - Intraocular lens.

    Science.gov (United States)

    2010-04-01

    ... DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3600 Intraocular lens. (a) Identification. An... the natural lens of an eye. (b) Classification. Class III. (c) Date PMA or notice of completion of a...

  5. [Contact lens-associated Paecilomyces lilacinus keratitis].

    Science.gov (United States)

    Mihailovic, N; Alnawaiseh, M; Zumhagen, L; Eter, N

    2017-01-01

    We present the case of a 23-year-old otherwise healthy female patient with contact lens-associated Paecilomyces lilacinus keratitis. The clinical findings stabilized after initial local antimycotic and antibacterial treatment; however, in the further course of local therapy an extensive relapse occurred which required treatment by perforating keratoplasty à chaud due to a penetrating corneal ulcer. The patient responded well to subsequent treatment with systemic and local antimycotic medication. After a few months HLA-matched keratoplasty was performed. During the follow-up time of 14 months there were no signs of recurrence of the infection.

  6. Histochemical analysis of bandage contact lens precipitates.

    Science.gov (United States)

    Nessim, Maged; Pandey, Suresh K; Werner, Liliana; Mohammed, Musadiq; Kumar, Vinod

    2008-02-01

    Contact lens deposits have been reported previously with extended wear of soft contact lenses, with proteins, lipids, mucous, and various salts such as chloride, potassium and calcium being deposited on the lens surface [1]. We report an unusual case of precipitates on the surface of a bandage contact lens (BCL) following intensive treatment with topical preservative free artificial tears. Evaluation included microscopic and histochemical analysis of the BCL. We have also reviewed the literature for previous reports of contact lens precipitates.

  7. An integral-field spectroscopic strong lens survey

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, Adam S [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS-20, Cambridge, MA 02138 (United States); Burles, Scott [Department of Physics and Kavli Institute, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

    2007-12-15

    We present the observational results of a survey for strong gravitational lens systems consisting of extended emission-line galaxies lensed by intervening early-type galaxies, conducted using integral field units (IFUs) of the Magellan IMACS and Gemini GMOS-N spectrographs. These data are highly valuable for corroborating the lensing interpretation of Hubble Space Telescope imaging data. We show that in many cases, ground-based IFU spectroscopy is in fact competitive with space-based imaging for the measurement of the mass model parameters of the lensing galaxy. We demonstrate a novel technique of three-dimensional gravitational lens modeling for a single lens system with a resolved lensed rotation curve. We also describe the details of our custom IFU data analysis software, which performs optimal multi-fiber extraction, relative and absolute wavelength calibration to a few hundredths of a pixel RMS and nearly Poisson-limited sky subtraction.

  8. Implementation of an aerodynamic lens for TRIGA-SPEC

    Science.gov (United States)

    Grund, J.; Düllmann, Ch. E.; Eberhardt, K.; Nagy, Sz.; van de Laar, J. J. W.; Renisch, D.; Schneider, F.

    2016-06-01

    We report on the optimization of the gas-jet system employed to couple the TRIGA-SPEC experiment to the research reactor TRIGA Mainz. CdI2 aerosol particles suspended in N2 as carrier gas are used for an effective transport of fission products from neutron induced 235 U fission from the target chamber to a surface ion source. Operating conditions of the gas-jet were modified to enable the implementation of an aerodynamic lens, fitting into the limited space available in front of the ion source. The lens boosts the gas-jet efficiency by a factor of 4-10. The characterization of the gas-jet system as well as the design of the aerodynamic lens and efficiency studies are presented and discussed.

  9. Quantitative Analysis of Lens Nuclear Density Using Optical Coherence Tomography (OCT with a Liquid Optics Interface: Correlation between OCT Images and LOCS III Grading

    Directory of Open Access Journals (Sweden)

    You Na Kim

    2016-01-01

    Full Text Available Purpose. To quantify whole lens and nuclear lens densities using anterior-segment optical coherence tomography (OCT with a liquid optics interface and evaluate their correlation with Lens Opacities Classification System III (LOCS III lens grading and corrected distance visual acuity (BCVA. Methods. OCT images of the whole lens and lens nucleus of eyes with age-related nuclear cataract were analyzed using ImageJ software. The lens grade and nuclear density were represented in pixel intensity units (PIU and correlations between PIU, BCVA, and LOCS III were assessed. Results. Forty-seven eyes were analyzed. The mean whole lens and lens nuclear densities were 26.99 ± 5.23 and 19.43 ± 6.15 PIU, respectively. A positive linear correlation was observed between lens opacities (R2 = 0.187, p<0.01 and nuclear density (R2 = 0.316, p<0.01 obtained from OCT images and LOCS III. Preoperative BCVA and LOCS III were also positively correlated (R2 = 0.454, p<0.01. Conclusions. Whole lens and lens nuclear densities obtained from OCT correlated with LOCS III. Nuclear density showed a higher positive correlation with LOCS III than whole lens density. OCT with a liquid optics interface is a potential quantitative method for lens grading and can aid in monitoring and managing age-related cataracts.

  10. The nature of ultra-massive lens galaxies

    Science.gov (United States)

    Canameras, Raoul

    2017-08-01

    During the past decade, strong gravitational lensing analyses have contributed tremendously to the characterization of the inner properties of massive early-type galaxies, beyond the local Universe. Here we intend to extend studies of this kind to the most massive lens galaxies known to date, well outside the mass limits investigated by previous lensing surveys. This will allow us to probe the physics of the likely descendants of the most violent episodes of star formation and of the compact massive galaxies at high redshift. We propose WFC3 imaging (F438W and F160W) of four extremely massive early-type lens galaxies at z 0.5, in order to put them into context with the evolutionary trends of ellipticals as a function of mass and redshift. These systems were discovered in the SDSS and show one single main lens galaxy with a stellar mass above 1.5x10^12 Msun and large Einstein radii. Our high-resolution spectroscopic follow-up with VLT/X-shooter provides secure lens and source redshifts, between 0.3 and 0.7 and between 1.5 and 2.5, respectively, and confirm extreme stellar velocity dispersions > 400 km/s for the lenses. The excellent angular resolution of the proposed WFC3 imaging - not achievable from the ground - is the remaining indispensable piece of information to :(1) Resolve the lens structural parameters and obtain robust measurements of their stellar mass distributions,(2) Model the amount and distribution of the lens total masses and measure their M/L ratios and stellar IMF with joint strong lensing and stellar dynamics analyses,(3) Enhance our on-going lens models through the most accurate positions and morphologies of the blue multiply-imaged sources.

  11. Lens thickness assessment: anterior segment optical coherence tomography versus A-scan ultrasonography

    Directory of Open Access Journals (Sweden)

    Nikoo Hamzeh

    2015-12-01

    Full Text Available AIM: To assess lens thickness measurements with anterior segment-optical coherence tomography (AS-OCT in comparison with A-scan ultrasonography (A-scan US. METHODS: There were 218 adult subjects (218 eyes aged 59.2±9.2y enrolled in this prospective cross-sectional study. Forty-three eyes had open angles and 175 eyes had narrow angles. Routine ophthalmic exam was performed and nuclear opacity was graded using the Lens Opacities Classification System III (LOCS III. Lens thickness was measured by AS-OCT (Visante OCT, Carl Zeiss Meditec, Dublin, CA, USA. The highest quality image was selected for each eye and lens thickness was calculated using ImageJ software. Lens thickness was also measured by A-scan US. RESULTS: Interclass correlations showed a value of 99.7% for intra-visit measurements and 95.3% for inter-visit measurements. The mean lens thickness measured by AS-OCT was not significantly different from that of A-scan US (4.861±0.404 vs 4.866±0.351 mm, P=0.74. Lens thickness values obtained from the two instruments were highly correlated overall (Pearson correlation coefficient=0.81, P<0.001, and in all LOCS III specific subgroups except in grade 5 of nuclear opacity. Bland-Altman analysis revealed a 95% limit of agreement from -0.45 to 0.46 mm. Lens thickness difference between the two instruments became smaller as the lens thickness increased and AS-OCT yielded smaller values than A-scan US in thicker lens (β=-0.29, P<0.001 CONCLUSION: AS-OCT-derived lens thickness measurement is valid and comparable to the results obtained by A-scan US. It can be used as a reliable noncontact method for measuring lens thickness in adults with or without significant cataract.

  12. Luneburg modified lens for surface water waves

    Science.gov (United States)

    Pichard, Helene; Maurel, Agnes; Petitjeans, Phillipe; Martin, Paul; Pagneux, Vincent

    2015-11-01

    It is well known that when the waves pass across an elevated bathymetry, refraction often results in amplification of waves behind it. In this sense, focusing of liquid surface waves can be used to enhance the harvest efficiency of ocean power. An ocean wave focusing lens concentrates waves on a certain focal point by transforming straight crest lens of incident waves into circular ones just like an optical lens. These devices have attracted ocean engineers and are promising because they enable the effective utilization of wave energy, the remaining challenge being to increase the harvest efficiency of the lens. In this work, in order to improve well known focusing of surface liquid waves by lens, the propagation of liquid surface waves through a Luneburg modified lens is investigated. The traditional Luneburg lens is a rotationally symmetric lens with a spatially varying refractive-index profile that focuses an incident plane wave on the rim of the lens. The modified Luneburg lens allows to choose the position of the focal point, which can lie inside or outside the lens. This new degree of freedom leads to enhanced focusing and tunable focusing. The focusing of linear surface waves through this lens is investigated and is shown to be more efficient than classical profile lenses.

  13. A microcapillary lens for X-rays

    CERN Document Server

    Dudchik, Y I

    1999-01-01

    A new design of a compound refractive lens for X-rays is proposed. The lens is made as a set of glue microlenses placed in a glass capillary. The technique of lens fabrication is described. Results of ray tracing calculations for 8 and 15 keV photons are represented.

  14. Contact Lens-related Complications: A Review.

    Science.gov (United States)

    Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

    2017-01-01

    Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years.

  15. Contact lens-related complications: A review

    Directory of Open Access Journals (Sweden)

    Fateme Alipour

    2017-01-01

    Full Text Available Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years.

  16. Contact Lens-related Complications: A Review

    Science.gov (United States)

    Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

    2017-01-01

    Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years. PMID:28540012

  17. A planar lens based on the electrowetting of two immiscible liquids

    Science.gov (United States)

    Liu, Chao-Xuan; Park, Jihwan; Choi, Jin-Woo

    2008-03-01

    This paper reports the development and characterization of a planar liquid lens based on electrowetting. The working concept of electrowetting two immiscible liquids is demonstrated with measurement and characterization of contact angles with regard to externally applied electric voltages. Consequently, a planar liquid lens is designed and implemented based on this competitive electrowetting. A droplet of silicone oil confined in an aqueous solution (1% KCl) works as a liquid lens. Electrowetting then controls the shape of the confined silicone oil and the focal length of the liquid lens varies depending upon an applied dc voltage. A unique feature of this lens design is the double-ring planar electrodes beneath the hydrophobic substrate. While an outer ring electrode provides an initial boundary for the silicone oil droplet, an inner ring works as the actuation electrode for the lens. Further, the planar electrodes, instead of vertical or out-of-plane wall electrodes, facilitate the integration of liquid lenses into microfluidic systems. With the voltage applied in the range of 50-250 V, the confined silicone oil droplet changed its shape and the optical magnification of a 3 mm-diameter liquid lens was clearly demonstrated. Moreover, focal lengths of liquid lenses with diameters of 2 mm, 3 mm and 4 mm were characterized, respectively. The obtained results suggest that a larger lens diameter yields a longer focal length and a wider range of focal length change in response to voltage. The demonstrated liquid lens has a simple structure and is easy to fabricate.

  18. Professoren og Ålen

    DEFF Research Database (Denmark)

    Poulsen, Bo

    2016-01-01

    Biolog og havforsker Johannes Schmidt regnes for at være Danmarks mest betydningsfulde havforsker gennem tiderne. Hans mange forskningsbaserede jordomsejlinger bragte ham til eksotiske egne og til opdagelsen af adskillige nye dyrearter. Dog blev særligt ålen og dens gydepladser et hovedfokus...

  19. Femtosecond Kerr-lens autocorrelation.

    Science.gov (United States)

    Sheik-Bahae, M

    1997-03-15

    An autocorrelation measurement of femtosecond laser pulse duration using the Kerr-lens mechanism is demonstrated. This technique can also be used as a sensitive and absolutely calibratable method for measuring ultrafast optical nonlinearities. A method that uses an electronic spectral-filtering scheme is proposed for determining the frequency chirp of pulses by interferometric autocorrelation.

  20. The Ultrawideband Leaky Lens Antenna

    NARCIS (Netherlands)

    Bruni, S.; Neto, A.; Marliani, F.

    2007-01-01

    A novel directive and nondispersive antenna is presented: the ultrawideband (UWB) leaky lens. It is based on the broad band Cherenkov radiation occurring at a slot printed between different infinite homogeneous dielectrics. The first part of the paper presents the antenna concept and the UWB design.

  1. Tube entrance lens focus control

    Science.gov (United States)

    Weisser, D. C.; Fifield, L. K.; Kitchen, T. F. G.; Tunningley, T. B.; Lobanov, N. R.; Muirhead, A. G.

    2013-02-01

    The entrance of the accelerator tube in a large electrostatic accelerator imposes a strong lens that dominates the beam optics. The magnification of the lens is large because of the low injection energy, the high voltage gradient of the acceleration tube and the long distance to the terminal. In the absence of the acceleration, the magnification would produce an unacceptably large beam spot at the terminal. The tyranny of the lens is especially irksome when the accelerator is required to operate at a lower terminal voltage than the one corresponding to the nominal gradient at high voltage. One way around the difficulty, used in NEC Pelletron accelerators, is to insert a series of nylon and steel rods that short together units of the acceleration structure at the terminal leaving the ones near the entrance close to the nominal gradient for optimum transmission. This operation takes time and risks the loss of insulating gas. Another alternative used in the 25URC at Oak Ridge National Laboratory, is to focus the beam at the tube entrance, substantially diluting the effect of the entrance lens. The beam then diverges and so requires an additional lens part way to the terminal. This solution is only partially effective and still necessitates use of shorting rods for low voltage operation. The fact that these elaborate strategies are used is evidence that the alternative of lowering the injection energy as the terminal voltage is lowered imposes enough problems that it is not used in practice. We have modeled a solution that controls the voltage gradient at the tube entrance using an external power supply. This not only maintains the focusing effect of the lens but provides the opportunity to tune the beam by adjusting the entrance lens. A 150 kV power supply outside the pressure vessel feeds a controllable voltage through a high voltage feed-through to the fifth electrode of the accelerator tube. Thus 150 kV on this electrode creates the nominal gradient of 30 kV per

  2. Multifocal contact lens myopia control.

    Science.gov (United States)

    Walline, Jeffrey J; Greiner, Katie L; McVey, M Elizabeth; Jones-Jordan, Lisa A

    2013-11-01

    Previous studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years. Eight- to eleven-year-old children with -1.00 D to -6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal "D"; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers. Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was -1.03 ± 0.06 D for the single-vision contact lens wearers and -0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016). Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.

  3. Impact of soft contact lens edge design and midperipheral lens shape on the epithelium and its indentation with lens mobility.

    Science.gov (United States)

    Wolffsohn, James S; Drew, Thomas; Dhallu, Sandeep; Sheppard, Amy; Hofmann, Greg J; Prince, Mark

    2013-09-11

    To evaluate the influence of soft contact lens midperipheral shape profile and edge design on the apparent epithelial thickness and indentation of the ocular surface with lens movement. Four soft contact lens designs comprising of two different plano midperipheral shape profiles and two edge designs (chiseled and knife edge) of silicone-hydrogel material were examined in 26 subjects aged 24.7 ± 4.6 years, each worn bilaterally in randomized order. Lens movement was imaged enface on insertion, at 2 and 4 hours with a high-speed, high-resolution camera simultaneous to the cross-section of the edge of the contact lens interaction with the ocular surface captured using optical coherence tomography (OCT) nasally, temporally, and inferiorly. Optical imaging distortions were individually corrected for by imaging the apparent distortion of a glass slide surface by the removed lens. Apparent epithelial thickness varied with edge position (P design. Horizontal and vertical lens movement did not change with time postinsertion. Vertical motion was affected by midperipheral lens shape profile (P design (P designs. Dynamic OCT coupled with high-resolution video demonstrated that soft contact lens movement and image-corrected ocular surface indentation were influenced by both lens edge design and midperipheral lens shape profiles.

  4. Time lens assisted photonic sampling extraction

    Science.gov (United States)

    Petrillo, Keith Gordon

    Telecommunication bandwidth demands have dramatically increased in recent years due to Internet based services like cloud computing and storage, large file sharing, and video streaming. Additionally, sensing systems such as wideband radar, magnetic imaging resonance systems, and complex modulation formats to handle large data transfer in telecommunications require high speed, high resolution analog-to-digital converters (ADCs) to interpret the data. Accurately processing and acquiring the information at next generation data rates from these systems has become challenging for electronic systems. The largest contributors to the electronic bottleneck are bandwidth and timing jitter which limit speed and reduce accuracy. Optical systems have shown to have at least three orders of magnitude increase in bandwidth capabilities and state of the art mode locked lasers have reduced timing jitters into thousands of attoseconds. Such features have encouraged processing signals without the use of electronics or using photonics to assist electronics. All optical signal processing has allowed the processing of telecommunication line rates up to 1.28 Tb/s and high resolution analog-to-digital converters in the 10s of gigahertz. The major drawback to these optical systems is the high cost of the components. The application of all optical processing techniques such as a time lens and chirped processing can greatly reduce bandwidth and cost requirements of optical serial to parallel converters and push photonically assisted ADCs into the 100s of gigahertz. In this dissertation, the building blocks to a high speed photonically assisted ADC are demonstrated, each providing benefits to its own respective application. A serial to parallel converter using a continuously operating time lens as an optical Fourier processor is demonstrated to fully convert a 160-Gb/s optical time division multiplexed signal to 16 10-Gb/s channels with error free operation. Using chirped processing, an

  5. Eye lens in aging and diabetes: effect of quercetin.

    Science.gov (United States)

    Stefek, Milan; Karasu, Cimen

    2011-10-01

    Old age is accompanied by a number of pathological eye conditions. Cataract is the most common age-related eye complication. Because the lens becomes naturally more opaque over time, aging is the most important risk factor for developing cataract, which is a major cause of blindness in the world. Cataractogenesis is also one of the earliest secondary complications of diabetes mellitus. The lens is a closed system with limited capability to repair or regenerate itself. Current evidence supports the view that cataractogenesis is a multifactorial process. Oxidative stress and its sequelae are clearly involved in the etiology of senile cataract, whereas mechanisms related to glucose toxicity, namely oxidative stress, processes of nonenzymatic glycation, and enhanced polyol pathway contribute significantly to the development of the eye complications under conditions of diabetes. There is an urgent need for inexpensive, nonsurgical approaches to the treatment of cataract. Recently, considerable attention has been devoted to the search for phytochemical therapeutics. Several pharmacological actions of natural flavonoids may operate in preventing cataract because flavonoids are capable of affecting multiple mechanisms or etiological factors responsible for the development of sight-threatening ocular diseases. The flavonol quercetin is the most widely consumed flavonoid in the human diet. In this article, quercetin is reviewed as an agent that could reduce the risk of cataract formation via affecting multiple pathways pertinent to eye lens opacification, including oxidative stress, nonenzymatic glycation, the polyol pathway, lens calpain proteases, and epithelial cell signaling. In addition, the bioavailability of quercetin to the lens is considered.

  6. Oral Morphine Consumption Reduces Lens Development in Rat Embryos

    Directory of Open Access Journals (Sweden)

    Hossein Bahadoran

    2012-07-01

    Full Text Available Objective: Consumption of morphine, during pregnancy, in addition to inducing defects in the mother’s nervous system function, caused defects or delays in the formation and evolution of embryonic visual system. In the present study, changes in lens development was assessed in embryos exposed in utero to morphine. Material and Methods: Female Wistar rats (250-300 g were mated with male rats and pregnancy was determined by sperm observation in vaginal smear. This day was considered as embryonic day zero (E0. The females were then divided randomly into the experimental and the control groups. The control group received tap water and the experimental group received morphine (0.05 mg/ml in their water. On embryonic day 13 ( E13, blood samples were collected from the retro-orbital sinus of all animals for plasma corticosterone detection. On embryonic day 17(E17, the animals were killed by an overdose of chloroform and the embryos were taken out surgically. The embryos were fixed in 10% formalin for 30 days. At this time, the head of the embryos were removed for tissue processing and Hematoxylin- Eosin (H&E staining. The samples were evaluated using light microscope and MOTIC software. Results: Our data indicated that plasma corticosterone level was dramatically increased and the lens was thinner in the experimental group. (Although the proliferation of lens cells increased in the experiment group but that lens had delay in removing the proliferated and elongation cells with abnormal density in the lateral part of the lens in compare with control group. I have no idea what the authors are stating here. Moreover, the opening of the eyelids was delayed in the off springs of the mothers who received morphine. Conclusions: This study showed that morphine consumption during pregnancy leads to defects in fetal visual system development, particularly in the lens, and eyelids.

  7. Herstellung und Untersuchung metallischer Einzel-Elektronen-Transistoren

    OpenAIRE

    Hofmann, Karl

    2001-01-01

    Single-electron transistors (SETs) are quantum devices and are based on the controlling of the Coulomb blockade. They are the ultimate development of low-power devices with an extreme high potential of integration. Their dominant purpose is seen in future memory devices. Usually the key element of all metallic SETs is a tunnel junction consisting of a metal-insulator-metal transition. In this current thesis the microscopic and electrical investigations of e-gun evaporated titanium thin films ...

  8. Contact lens surface by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jung Hyuck [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Suk Ju; Hwang, Kwang Ha; Jeon Jin [Dongshin Univ., Naju (Korea, Republic of)

    2011-07-01

    Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility.

  9. Photonic crystal planar lens working at low frequencies

    Science.gov (United States)

    Lu, Zhaolin; Shi, Shouyuan; Schuetz, Christopher A.; Lin, Chunchen; Chen, Caihua; Sharkawy, Ahmed S.; Prather, Dennis W.

    2005-04-01

    In this paper, we demonstrate the design and fabrication of a planar lens based on the dispersion property of a photonic crystal. When a photonic crystal is illuminated with a low frequency within its dispersion diagram it behaves very similar to an isotropic material, whose resultant index is kept a constant, and is determined by the ratio of high index material and low index material. To validate our design, we performed the experiment in millimeter regime, where the photonic crystal lens was fabricated using a CNC micro-milling machine, and a millimeter wave imaging system was built based on a vector network analyzer. For the lens, we have observed its ability to collimate an incident point source both in the amplitude and phase.

  10. [Water-cushion contact lens for pars plana vitrectomy].

    Science.gov (United States)

    Klöti, R

    1983-01-01

    Our water-cushion contact lens satisfies same requirements as the lenses we used previously: stabilization of the anterior segment, perfect attachment to the eye, freedom of movement of the eye in all directions. A rather important additional advantage is achieved by virtue of the fact that the lens floats on a constantly renewed fluid layer in a ring-shaped pool. Even in diabetic patients postoperative damage to the corneal epithelium no longer occur. A planoconcave or prismatic quartz lens may be placed into the pool. The lenses are scratch-resistant and have an antireflective coating. Direct observation of the equatorial area in phakic and of the oraserrata area in aphakic eyes is possible with this perfect optical system.

  11. Forgotten Forests? Food Potential of Ancient Coffee Forests and Agroforestry Systems in the Southwestern Ethiopian Mountains, Seen Through a Gender Lens

    Directory of Open Access Journals (Sweden)

    Sarah Marie Nischalke

    2017-08-01

    Full Text Available Forests play an important role in the provision of food and livelihoods across the globe. Thus, forest protection contributes to a diverse set of Sustainable Development Goals. The Yayu Coffee Forest Biosphere Reserve in the southwestern Ethiopian mountains (elevation 1100–2300 m above sea level hosts an ancient coffee forest with high biodiversity and a large nutritional potential. It is managed in zones, and smallholder farmers can still use forest resources in the buffer and transitional zones in a sustainable manner. The forest is rarely used as a food source, although a large majority of the population in this area suffers from micronutrient deficiencies. This article investigates whether sustainable use of forest resources can contribute to the achievement of different Sustainable Development Goals by looking, through a gender lens, at which forest ecosystem services the community uses; traditional coffee farmers' perceptions of wild edible plants, agricultural territories, and labor divisions; and the constraining factors for forest conservation and sustainable agroforestry on private forest plots. Data for this study were collected through ethnography, transect walks, a sex-disaggregated household survey (n = 334, 32 semistructured interviews, 40 focus groups, and 13 key stakeholder interviews. One reason for neglecting the forest as a food source is that forests are considered a male territory, while vegetable raising and nutrition are female responsibilities. In addition, the collection of wild foods is perceived as a last resort during a famine and as a practice of tribal groups. Because coffee production represents the traditional livelihood source, farmers accept the need to conserve the forest, which is necessary to achieve the Sustainable Development Goals. While it may have negative implications for food security, the absence of a tradition of collecting wild plants is positive news for forest conservation.

  12. Modeling the evaporation of a pre-lens tear film on a contact lens

    Science.gov (United States)

    Anderson, Daniel; Talbott, Kevin; Xu, Amber; Seshaiyer, Padmanabhan

    2011-11-01

    We develop a model for evaporation of a post-blink pre-lens tear film in the presence of a porous contact lens. The tear film is modeled as a Newtonian fluid and the flow in the contact lens is assumed to obey Darcy's law. The evaporation model treats the contact lens as a wetting surface. Evaporative mass flux thins the pre-lens film down to a nonzero steady thickness at which point evaporation continues by drawing fluid up through the contact lens. Both one and two-dimensional models are explored. The post-lens film (between the contact lens and the corneal surface) is not included explicitly in the model but is assumed to act as a reservoir that supplies fluid drawn up through the contact lens. Supported by NSF CSUMS and REU programs.

  13. Glue test results for high-precision large cryogenic lens holder

    Science.gov (United States)

    Reutlinger, A.; Mottaghibonab, A.; Gal, C.; Boesz, A.; Grupp, F.; Geis, N.; Bode, A.; Katterloher, R.; Bender, R.

    2012-09-01

    The Near Infrared Spectrometer and Photometer (NISP) of EUCLID requires high precision large lens holders (Ø170 mm) at cryogenic temperatures (150 K). The lenses of the optical system are glued into separate lens holders, the so called adaption rings. For the selection and verification of a suitable adhesive extensive glue selection tests are performed and results presented in this paper. With potential glue candidates, handling, single lap shear, connection tension and shear tests are carried out at room temperature (RT) and 150 K (OPS). For the NISP optical system DP490 is selected as the most suitable adhesive. The test results have shown that an even distribution of the glue in the glue gap is of crucial importance for the functioning and performance of the bonded lens system. The different coefficients of thermal expansion (CTE) between lens and lens holder produce large local mechanical stress and might cause lens breakage or failure of bonding. The design of the injection channel and the gluing procedure are developed to meet the lens performance requirements. An example is shown that after thermal cycling the remaining 0.5 mm - 1 mm thick adhesive in the injection channel results in large local mechanical stresses, and hence, damage of the lens. For a successful performance of the glue interface not only an optimum glue gap of 80 - 150 μm is important, also micro-cracks of the glass at the gluing area have to be avoided. The performed glue tests with DP490 for 3 different lens/ring material combinations show sufficient mechanical tension and shear strength for bonding of the lens system. Titanium/LF5G15 and Invar/Fused Silica combinations have reached the strength of 30 MPa at RT and 50 GPa at 150 K. These results are presented on behalf of the EUCLID consortium.

  14. Astronomers Discover Six-Image Gravitational Lens

    Science.gov (United States)

    2001-08-01

    An international team of astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope and NASA's Hubble Space Telescope (HST) to discover the first gravitational lens in which the single image of a very distant galaxy has been split into six different images. The unique configuration is produced by the gravitational effect of three galaxies along the line of sight between the more-distant galaxy and Earth. Optical and Radio Images of Gravitational Lens "This is the first gravitational lens with more than four images of the background object that is produced by a small group of galaxies rather than a large cluster of galaxies," said David Rusin, who just received his Ph.D. from the University of Pennsylvania. "Such systems are expected to be extremely rare, so this discovery is an important stepping stone. Because this is an intermediate case between gravitational lenses produced by single galaxies and lenses produced by large clusters of galaxies, it will give us insights we can't get from other types of lenses," Rusin added. The gravitational lens, called CLASS B1359+154, consists of a galaxy more than 11 billion light-years away in the constellation Bootes, with a trio of galaxies more than 7 billion light-years away along the same line of sight. The more-distant galaxy shows signs that it contains a massive black hole at its core and also has regions in which new stars are forming. The gravitational effect of the intervening galaxies has caused the light and radio waves from the single, more-distant galaxy to be "bent" to form six images as seen from Earth. Four of these images appear outside the triangle formed by the three intermediate galaxies and two appear inside that triangle. "This lens system is a very interesting case to study because it is more complicated than lenses produced by single galaxies, and yet simpler than lenses produced by clusters of numerous galaxies," said Chris Kochanek of the Harvard

  15. Compliance and hygiene behaviour among soft contact lens wearers in the Maldives.

    Science.gov (United States)

    Gyawali, Rajendra; Nestha Mohamed, Fathimath; Bist, Jeewanand; Kandel, Himal; Marasini, Sanjay; Khadka, Jyoti

    2014-01-01

    Significant levels of non-compliance and poor hygiene among contact lens wearers have been reported previously from different parts of the world. This survey aimed at identifying the scope of hygiene and non-compliant behaviour of soft contact lens wearers in the Maldives. Established soft lens wearers attending two eye clinics in Male' city, were interviewed in office or via telephone. A set of interviewer-administered questions was used to access the subjective response on compliance and hygiene behaviour (hand and lens case hygiene, water exposure, adherence to lens replacement schedule, dozing and overnight wear, awareness of aftercare visits and reuse of disinfecting solution). Participants were also asked to rate themselves as a contact lens user based on their perceived compliance and hygiene practices. Out of 107 participants, 79 (74.8 per cent) were interviewed in the office and the rest via telephone. The majority of lens wearers were female, office workers and students, with a mean age of 20.64 ± 4.4 years. Mean duration of lens wear was 28.04 ± 8.36 months. Most of them were using spherical lenses (86.9 per cent) on a daily wear basis (96.3 per cent). Major reported forms of non-compliance were poor hand hygiene (60.7 per cent), lack of aftercare awareness (39.3 per cent), water exposure (35.5 per cent) and over-use of lenses (24.3 per cent). While females were more likely to overuse their lenses than males (p hygienic behaviour. A significant number of Maldivian contact lens wearers exhibited poor levels of hygiene and compliance with contact lenses and lens care systems. An effective educational reinforcement strategy needs to be developed to modify lens wearers' non-compliance. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

  16. Fabricating customized hydrogel contact lens

    OpenAIRE

    Andre Childs; Hao Li; Daniella M. Lewittes; Biqin Dong; Wenzhong Liu; Xiao Shu; Cheng Sun; Zhang, Hao F.

    2016-01-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spe...

  17. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  18. CONTACT LENS RELATED CORNEAL ULCER

    Directory of Open Access Journals (Sweden)

    AGARWAL P

    2010-01-01

    Full Text Available A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are:overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection, severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss.

  19. Geometric optical optimization of the corneal lens of Notonecta glauca.

    Science.gov (United States)

    Horváth, G

    1989-08-09

    The optimal shape of the corneal lens of the water bug backswimmer (Notonecta glauca) and the optimal shape and position of the thin transition layer between the distal and proximal units of its cornea are theoretically determined. Using a geometric optical method, first the shape of a geometric interface between the lens units is determined, which eliminates the longitudinal spherical aberration. This interface is investigated for differently formed thick lenses when the medium in contact with the entrance surface of the lens is water or air. The optimal transition layer for the amphibious backswimmer is that, the boundaries of which are the theoretical interfaces for water and air, and the refractive index varies continuously in it. The optimal shape of the corneal lens is determined, with the disadvantageous lenses, with respect to the possible minimal spherical aberration and amount of reflected light from the transition layer, being rejected. The optimal position of the transition layer in the cornea can be obtained from the minimization of the amount of diffracted light on the marginal connection of the layers. The optimal corneal lens for backswimmer has ellipsoid boundary surfaces; the optimal transition layer in it is thin bell-shaped, at the marginal connection of which there is no dimple, the maximum of the layer is on the margin of the cornea. The shape of the theoretically optimal corneal lens, the shape and position of the theoretically optimal transition layer agree well with those of Notonecta glauca. The question posed, the geometric optical method used and the results presented are of general importance, and not only with respect to vision in the bug Notonecta, but also in the fossil trilobites, or in the wave guide theories which have been employed in similar modelling problems, in design of system of lenses without spherical aberration, for example.

  20. Three-dimensional broadband and high-directivity lens antenna made of metamaterials

    Science.gov (United States)

    Chen, Xi; Feng Ma, Hui; Ying Zou, Xia; Xiang Jiang, Wei; Jun Cui, Tie

    2011-08-01

    We present the theoretical modeling and prototype demonstration of a three-dimensional broadband, low-loss, dual-polarization, and high-directivity lens antenna using gradient index (GRIN) metamaterials, which is composed of multi-layer microstrip square-ring arrays. The elements of metamaterials, closed square-ring units of variable sizes, are distributed on the planar substrate to satisfy the radial gradient index function and the axial impedance matching layer configuration of the lens. The gradient-index metamaterials are designed to transform the spherical wave-front into the planar wave-front and to minimize the reflection loss. A prototype lens antenna, which consists of a metal conical horn and the gradient-index lens, are simulated, constructed, and measured. The resemblance of simulation and measurement results shows that the prototype lens antenna maintains low return loss and high directivity on the whole X-band (from 8 GHz to 12 GHz). Compared to the traditional horn antenna, the metamaterial GRIN lens antenna has much superior performance—for instance, the gain increases by 6 dBi at 12 GHz. These results demonstrate the feasibility of such a light weight slab metamaterial lens for broadband and high-directivity antenna applications, such as in radar and communication systems. We have used the lens antennas in the measurements of a three-dimensional invisibility cloak due to the high directivity.

  1. Prototype color field sequential television lens assembly

    Science.gov (United States)

    1974-01-01

    The design, development, and evaluation of a prototype modular lens assembly with a self-contained field sequential color wheel is presented. The design of a color wheel of maximum efficiency, the selection of spectral filters, and the design of a quiet, efficient wheel drive system are included. Design tradeoffs considered for each aspect of the modular assembly are discussed. Emphasis is placed on achieving a design which can be attached directly to an unmodified camera, thus permitting use of the assembly in evaluating various candidate camera and sensor designs. A technique is described which permits maintaining high optical efficiency with an unmodified camera. A motor synchronization system is developed which requires only the vertical synchronization signal as a reference frequency input. Equations and tradeoff curves are developed to permit optimizing the filter wheel aperture shapes for a variety of different design conditions.

  2. Trends of contact lens prescribing in Jordan.

    Science.gov (United States)

    Haddad, Mera F; Bakkar, May; Gammoh, Yazan; Morgan, Philip

    2016-10-01

    To evaluate contact lens prescribing trends among optometrists in Jordan. Optometrists from 173 practices in Jordan were surveyed about prescribing contact lenses in their practice. Practitioners were required to record information for the last 10 patients that visited their practice. Demographic data such as age and gender was obtained for each patient. In addition, data relating to lens type, lens design, replacement methods and the care regime advised to each patient were recorded. Practitioners were required to provide information relating to their education and years of experience. The influence of education and experience with respect to lens prescribing trends was explored using linear regression models for the proportions of lens types fitted for patients. A total of 1730 contact lens fits were analyzed. The mean (±SD) age of lens wearers was 26.6 (±7.9) years, of whom 65% were female. Conventional hydrogel lenses were the most prescribed lenses, accounting for 60.3% of the fits, followed by silicone hydrogel lenses (31.3%), and rigid lenses (8.4%). In terms of lens design, spherical lenses appeared to be most commonly prescribed on monthly basis. Daily disposable lenses were second most prescribed lens modality, accounting for 20.4% of the study sample. Multi-purpose solution (MPS) was the preferred care regimen, with a prevalence of 88.1% reported in the study sample, compared to hydrogen peroxide (1-step and 2-step), which represented only 2.8% of the patients in this study. A relationship was established between the two educational groups for rigid lens prescribing (F=17.4, p<0.0001), while the experience of the optometrist was not a significant factor (F=0.4, p=0.54). This work has provides an up-to-date analysis of contact lens prescribing trends among optometrists in Jordan. Contact lens prescribing in terms of lens type, lens design, modality of wear and care regimen agree with global market trends with small variations. This report will help

  3. The Sloan Lens ACS Survey. I. A Large Spectroscopically Selected Sample of Massive Early-Type Lens Galaxies

    Science.gov (United States)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Moustakas, Leonidas A.

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple nebular emission lines at a redshift significantly higher than that of the SDSS target galaxy. The SLACS survey is optimized to detect bright early-type lens galaxies with faint lensed sources in order to increase the sample of known gravitational lenses suitable for detailed lensing, photometric, and dynamical modeling. In this paper, the first in a series on the current results of our HST Cycle 13 imaging survey, we present a catalog of 19 newly discovered gravitational lenses, along with nine other observed candidate systems that are either possible lenses, nonlenses, or nondetections. The survey efficiency is thus >=68%. We also present Gemini 8 m and Magellan 6.5 m integral-field spectroscopic data for nine of the SLACS targets, which further support the lensing interpretation. A new method for the effective subtraction of foreground galaxy images to reveal faint background features is presented. We show that the SLACS lens galaxies have colors and ellipticities typical of the spectroscopic parent sample from which they are drawn (SDSS luminous red galaxies and quiescent MAIN sample galaxies), but are somewhat brighter and more centrally concentrated. Several explanations for the latter bias are suggested. The SLACS survey provides the first statistically significant and homogeneously selected sample of bright early-type lens galaxies, furnishing a powerful probe of the structure of early-type galaxies within the half-light radius. The high confirmation rate of lenses in the SLACS survey suggests consideration of spectroscopic lens discovery as an explicit science goal of future spectroscopic galaxy surveys.

  4. Evaluated Conjunctival Blood Flow Velocity in Daily Contact Lens Wearers.

    Science.gov (United States)

    Shi, Yingying; Hu, Liang; Chen, Wan; Qu, Dongyi; Jiang, Hong; Wang, Jianhua

    2017-04-13

    This study examined conjunctival microvasculature development in long-term habitual contact lens (HCL) wearers after a night of sleep. Twenty HCL wearers (15 women and 5 men, aged 28.6±6.9 years, mean age±standard deviation) who had worn contact lenses on a daily basis for at least 3 years and 40 noncontact lens (NCL) wearers (23 women and 17 men, aged 36.5±6.6 years, mean age±standard deviation) participated in the study. A functional slitlamp biomicroscopy imaging system was used to image the temporal bulbar conjunctiva. Imaging was performed in the morning while the contact lens wearers were not wearing their lenses after a night of sleep. The conjunctival vessel diameters, blood flow velocities, and flow rates were measured. In addition, fractal analyses were performed to obtain the vessel network density (Dbox) and complexity (D0). The average blood flow velocity in HCL wearers after a night of sleep was 0.59±0.19 mm/s, which was significantly higher than that in NCL wearers (0.48±0.17 mm/s, P<0.05). The microvessel network density and complexity levels (Dbox=1.64±0.05 and D0=1.71±0.05, respectively) in the HCL wearers were significantly higher than those in NCL wearers (Dbox=1.61±0.05 and D0=1.69±0.04, both P<0.05). The blood flow velocity was positively correlated with the duration of contact lens wear (r=0.46, P<0.05) and with the daily number of lens-wearing hours (r=0.49, P<0.05) in HCL wearers. This study identified microvascular alterations in the conjunctiva in response to daily contact lens wear after a night of sleep in long-term daily contact lens wearers. The unrecovered changes may indicate that para-inflammation occurs on ocular surfaces because of contact lens wear and that overnight sleeping with no lenses may not sufficiently restore the ocular surface to an intact state.

  5. Overall Design On Optical Lens Data Base (OLDB)

    Science.gov (United States)

    Huilin, Jiang; Daren, Yang; Xiangrong, Fang; Sen, Han; Shijun, Wu; Tao, Ken; Jiong, Liu

    1989-12-01

    We have set up Optical Lens Data Rase on VAX-8600 computer, compiled base management software and query software. filled up the data of typical lens over one thousand and optical material over one thousand kinds,and shall extend OLDB unceasingly. It is proved by test and use that WA performance is reliable, opertion is convenient, so that OLEW provides a kind of modern means raising design level, reducing repeated work, shortening research period for the worker of optical design. Optical Lens Data lase (OHO that is set up on the VAX-8600 computer is a kind of modern beans serving resear(h, education, production efficiently with summing-up, regulating and recordi rat, oplical design result last many years, collecting the lens data of high quality. It is beneficial to change the aspect of separating data for oplical design, stopping-up information and the situation for repeated work without the neressiiy. It has significant science value and socity benefit. Setting up 01,1)11 is also a branch subject of a main subject for "expert system of opthal instrument", and a important basis. After expert system is successfully developed, it is very beneficial to reducing person labour intensity, raising design quality, speeding up design rate of progress, shortening production period and reducing production cost, so that we have set up OLDB on VAX-8600 computer and its primary mould has basically been finished.

  6. Evolution of a pre and post lens tear film with a contact lens

    Science.gov (United States)

    Gerhart, Matthew; Anderson, Daniel

    2012-11-01

    The work is the development, implementation, and analysis of a two-dimensional tear film model including a porous contact lens. The geometry of the problem is: a pre-lens layer that is a thin tear film between the outside air and contact lens, a contact lens that is a rigid but movable porous substrate, and a post-lens layer that is a thin film layer between the contact lens and the cornea. We are looking at short and long term behavior of the evolution of the thin film in the pre-lens layer coupled with the porous layer and the thin squeeze film in the post-lens layer. We model the different behaviors that arise as the Darcy number, evaporation effects, and boundary flux conditions change.

  7. Contact lens fitting after photorefractive keratectomy.

    OpenAIRE

    Astin, C. L.; Gartry, D S; McG Steele, A. D.

    1996-01-01

    AIMS/BACKGROUND: This study evaluated contact lens fitting and the longer term response of the photorefractive keratectomy (PRK) cornea to lens wear. In PRK for myopia problems such as regression, anterior stromal haze, irregular astigmatism, halo aberration, and anisometropia have been reported. Certain patients therefore require contact lens correction to obtain best corrected visual acuity (BCVA). METHOD: From an original cohort of 80 patients, 15 were dissatisfied with their visual outcom...

  8. TU-E-201-00: Eye Lens Dosimetry for Patients and Staff

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  9. TU-E-201-02: Eye Lens Dosimetry From CT Perfusion Studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D. [Toshiba America Medical Systems (United States)

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  10. The Time Lens Concept Applied to Ultra-High-Speed OTDM Signal Processing

    DEFF Research Database (Denmark)

    Clausen, Anders; Palushani, Evarist; Mulvad, Hans Christian Hansen

    2013-01-01

    This survey paper presents some of the applications where the versatile time-lens concept successfully can be applied to ultra-high-speed serial systems by offering expected needed functionalities for future optical communication networks....

  11. Changes in lens stiffness due to capsular opacification in accommodative lens refilling

    NARCIS (Netherlands)

    Nibourg, Lisanne M.; Sharma, Prashant K.; van Kooten, Theo G.; Koopmans, Steven A.

    Accommodation may be restored to presbyopic lenses by refilling the lens capsular bag with a soft polymer. After this accommodative lens refilling prevention of capsular opacification is a requirement, since capsular opacification leads to a decreased clarity of the refilled lens. It has been

  12. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  13. Design and experimental study on Fresnel lens of the combination of equal-width and equal-height of grooves

    Science.gov (United States)

    Guo, Limin; Liu, Youqiang; Huang, Rui; Wang, Zhiyong

    2017-06-01

    High concentrating PV systems rely on large Fresnel lens that must be precisely oriented in the direction of the Sun to maintain high concentration ratio. We propose a new Fresnel lens design method combining equal-width and equal-height of grooves in this paper based on the principle of focused spot maximum energy. In the ring band near the center of Fresnel lens, the design with equal-width grooves is applied, and when the given condition is reached, the design with equal-height grooves is introduced near the edges of the Fresnel lens, which ensures all the lens grooves are planar. In this paper, we establish a Fresnel lens design example model by Solidworks, and simulate it with the software ZEMAX. An experimental test platform is built to test, and the simulation correctness is proved by experiments. Experimental result shows the concentrating efficiency of this example is 69.3%, slightly lower than the simulation result 75.1%.

  14. Assessing the changes in the biomechanical properties of the crystalline lens induced by cold cataract with air-pulse OCE

    Science.gov (United States)

    Wu, C.; Singh, M.; Liu, C.-H.; Han, Z.; Li, J.; Raghunathan, R.; Larin, K. V.

    2015-11-01

    A cataract is the increase in opacity of the crystalline lens that can pathologically degrade visual acuity. In this study, we utilized a phase-sensitive optical coherence elastography (OCE) system to study the effects of a cold cataract on the biomechanical properties of the porcine crystalline lens in vitro. The cold cataract was induced by placing the whole lens in a low temperature environment until the lens was obviously clouded. Air-pulse OCE measurements were conducted on 6 lenses before and after cold cataract induction. A low amplitude displacement (≤ 10 µm) was induced by a focused air-pulse and the temporal deformation profiles from the surface and within the lenses were analyzed. The results demonstrated that the stiffness of the porcine lens increased after induction of the cold cataract, and it demonstrated the feasibility of OCE to assess the biomechanical changes in the lens due to cataract.

  15. Quantitative Analysis of Lens Nuclear Density Using Optical Coherence Tomography (OCT) with a Liquid Optics Interface: Correlation between OCT Images and LOCS III Grading.

    Science.gov (United States)

    Kim, You Na; Park, Jin Hyoung; Tchah, Hungwon

    2016-01-01

    Purpose. To quantify whole lens and nuclear lens densities using anterior-segment optical coherence tomography (OCT) with a liquid optics interface and evaluate their correlation with Lens Opacities Classification System III (LOCS III) lens grading and corrected distance visual acuity (BCVA). Methods. OCT images of the whole lens and lens nucleus of eyes with age-related nuclear cataract were analyzed using ImageJ software. The lens grade and nuclear density were represented in pixel intensity units (PIU) and correlations between PIU, BCVA, and LOCS III were assessed. Results. Forty-seven eyes were analyzed. The mean whole lens and lens nuclear densities were 26.99 ± 5.23 and 19.43 ± 6.15 PIU, respectively. A positive linear correlation was observed between lens opacities (R (2) = 0.187, p density (R (2) = 0.316, p densities obtained from OCT correlated with LOCS III. Nuclear density showed a higher positive correlation with LOCS III than whole lens density. OCT with a liquid optics interface is a potential quantitative method for lens grading and can aid in monitoring and managing age-related cataracts.

  16. How Pre-Service Teachers Navigate Trade-Offs of Food Systems across Time Scales: A Lens for Exploring Understandings of Sustainability

    Science.gov (United States)

    Yamashita, Lina; Hayes, Kathryn; Trexler, Cary J.

    2017-01-01

    In response to the increasing recognition of the need for sustainable food systems, research on students' and educators' knowledge of food systems and sustainability more broadly has grown but has generally focused on what people "fail" to understand. Moving away from this deficit approach, the present study used semi-structured…

  17. Biofilm formation of Achromobacter xylosoxidans on contact lens.

    Science.gov (United States)

    Konstantinović, Neda; Ćirković, Ivana; Đukić, Slobodanka; Marić, Vesna; Božić, Dragana D

    2017-09-01

    Achromobacter spp. may contaminate lenses, lens cases, and contact lens solutions and cause ocular infections. The aim of this study was to investigate the possibility of isolated strain of Achromobacter xylosoxidans to form biofilm on the surface of soft contact lenses (CL), to quantify the production of the formed biofilm, and compare it with the reference strains (Pseudomonas aeruginosa, Staphylococcus aureus, and Haemophilus influenzae). Bacterial strain isolated from one contact lens case was identified as A. xylosoxidans using Vitek2 Automated System. Biofilm forming capacity of isolated strain of A. xylosoxidans and reference strains of P. aeruginosa, S. aureus, and H. influenzae on soft CL were analyzed by commonly used microtitre plate method. Our results showed that isolated strain of A. xylosoxidans was capable to form biofilm on the surface of soft contact lens. A. xylosoxidans was strong biofilm producer while all examined reference strains were moderate biofilm producers. A. xylosoxidans appears to be superior biofilm producer on soft CL compared to reference strains.

  18. Portraiture lens concept in a mobile phone camera

    Science.gov (United States)

    Sheil, Conor J.; Goncharov, Alexander V.

    2017-11-01

    A small form-factor lens was designed for the purpose of portraiture photography, the size of which allows use within smartphone casing. The current general requirement of mobile cameras having good all-round performance results in a typical, familiar, many-element design. Such designs have little room for improvement, in terms of the available degrees of freedom and highly-demanding target metrics such as low f-number and wide field of view. However, the specific application of the current portraiture lens relaxed the requirement of an all-round high-performing lens, allowing improvement of certain aspects at the expense of others. With a main emphasis on reducing depth of field (DoF), the current design takes advantage of the simple geometrical relationship between DoF and pupil diameter. The system has a large aperture, while a reasonable f-number gives a relatively large focal length, requiring a catadioptric lens design with double ray path; hence, field of view is reduced. Compared to typical mobile lenses, the large diameter reduces depth of field by a factor of four.

  19. Enhancement of elastic wave energy harvesting using adaptive piezo-lens

    Science.gov (United States)

    Yi, K.; Collet, M.; Chesne, S.; Monteil, M.

    2017-09-01

    This paper exploits an adaptive piezo-lens to improve the harvested power (energy) from traveling waves. The piezo-lens comprises a host plate and piezoelectric patches bonded on the plate surfaces. The piezoelectric patches are shunted with negative capacitance (NC) circuits. The spatial variation of the refractive index inside the piezo-lens domain is designed to fulfill a hyperbolic secant function by tuning the NC values. This design allows the piezo-lens to continuously bend the incident waves toward a designed focal point, resulting in an energy concentration zone with a high level of energy density. This energy concentration effect may be exploited to improve the harvested power from waves. In addition, the piezo-lens is tunable - the waves can be focused at different locations by designing the NC values. This tunability may make the harvesting systems incorporating a piezo-lens be adaptable to environment changes. The above expected practical interests of the piezo-lens for wave energy harvesting are discussed and verified in the paper. Fully coupled numerical models are developed to predict the dynamical responses of the piezoelectric systems.

  20. Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

    Energy Technology Data Exchange (ETDEWEB)

    Buzhynskyy, Nikolay; Scheuring, Simon [Institut Curie, Equipe Inserm Avenir, UMR168-CNRS, 26 Rue d' Ulm, 75248 Paris Cedex 05 (France); Sens, Pierre [ESPCI, CNRS-UMR 7083, 75231 Paris (France); Behar-Cohen, Francine, E-mail: simon.scheuring@curie.fr [UMRS Inserm 872, Universite Paris Descartes, Centre de Recherches des Cordeliers, 15 rue de l' Ecole de Medecine, 75270 Paris Cedex 06 (France)

    2011-08-15

    The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

  1. Non-contact optical measurement of lens capsule thickness during simulated accommodation

    Science.gov (United States)

    Ziebarth, Noel; Manns, Fabrice; Acosta, Ana-Carolina; Parel, Jean-Marie

    2005-04-01

    Purpose: To non-invasively measure the thickness of the anterior and posterior lens capsule, and to determine if it significantly changes during accommodation. Methods: Anterior and posterior capsule thickness was measured on post-mortem lenses using a non-contact optical system using a focus-detection technique. The optical system uses a 670nm laser beam delivered to a single-mode fiber coupler. The output of the fiber coupler is focused on the tissue surface using an aspheric lens (NA=0.68) mounted on a translation stage with a motorized actuator. Light reflected from the sample surface is collected by the fiber coupler and sent to a photoreceiver connected to a computer-controlled data acquisition system. Optical intensity peaks are detected when the aspheric lens is focused on the capsule boundaries. The capsule thickness is equal to the distance traveled between two peaks multiplied by the capsule refractive index. Anterior and posterior lens capsule thickness measurements were performed on 18 cynomolgus (age average: 6+/-1 years, range: 4-7 years) eyes, 1 rhesus (age: 2 years) eye, and 12 human (age average: 65+/-16, range: 47-92) eyes during simulated accommodation. The mounted sample was placed under the focusing objective of the optical system so that the light was incident on the center pole. Measurements were taken of the anterior lens capsule in the unstretched and the stretched 5mm states. The lens was flipped, and the same procedure was performed for the posterior lens capsule. Results: The precision of the optical system was determined to be +/-0.5um. The resolution is 4um and the sensitivity is 52dB. The human anterior lens capsule thickness was 6.0+/-1.2um unstretched and 4.9+/-0.9um stretched (p=0.008). The human posterior lens capsule was 5.7+/-1.2um unstretched and 5.7+/-1.4um stretched (p=0.974). The monkey anterior lens capsule thickness was 5.9+/-1.9um unstretched and 4.8+/-1.0um stretched (p=0.002). The monkey posterior lens capsule was 5

  2. Development of an in vivo visual robot system with a magnetic anchoring mechanism and a lens cleaning mechanism for laparoendoscopic single-site surgery (LESS).

    Science.gov (United States)

    Feng, Haibo; Dong, Dinghui; Ma, Tengfei; Zhuang, Jinlei; Fu, Yili; Lv, Yi; Li, Liyi

    2017-12-01

    Surgical robot systems which can significantly improve surgical procedures have been widely used in laparoendoscopic single-site surgery (LESS). For a relative complex surgical procedure, the development of an in vivo visual robot system for LESS can effectively improve the visualization for surgical robot systems. In this work, an in vivo visual robot system with a new mechanism for LESS was investigated. A finite element method (FEM) analysis was carried out to ensure the safety of the in vivo visual robot during the movement, which was the most important concern for surgical purposes. A master-slave control strategy was adopted, in which the control model was established by off-line experiments. The in vivo visual robot system was verified by using a phantom box. The experiment results show that the robot system can successfully realize the expected functionalities and meet the demands of LESS. The experiment results indicate that the in vivo visual robot with high manipulability has great potential in clinical application. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Fabricating customized hydrogel contact lens

    Science.gov (United States)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  4. PREVALENCE OF LENS OPACITY AT QUEEN ELIZABETH ...

    African Journals Online (AJOL)

    hi-tech

    of the optical homogeneity of the lens and this definition includes lens vacuoles, water clefts, dense areas, ... health needs, and to determine the risk factors that influence the social and economic burden associated with the .... hazards of jobs mainly reserved for individual sexes. On the other hand, some studies have shown ...

  5. [Contact lens in children: epidemiological aspects].

    Science.gov (United States)

    Salame, André Luiz Alves; Simon, Eduardo José Maidana; Leal, Fernando; Lipener, César; Brocchetto, Daniela

    2008-01-01

    To describe the epidemiology of children submitted to contact lens fit. Retrospective study of 73 children that had been submitted to contact lens fit at the "Universidade Federal de São Paulo". This study analyzed sex distribution, age, diagnosis, indications and contact lens fitted at first examination. 34 children (46.6%) were male and 39 (53.4%) female, aged between 2 and 12 years with mean of 10.2 and standard deviation of 2.42. The most common diagnosis was aphakia, in 16 (21.9%) cases. Keratoconus was present in 14 (19.1%), leucoma in 11 (15%), anisometropia in 10 (13.7%), refractive errors in 9 (12.3%), irregular astigmatism in 7 (9.5%), ectopia lentis in 4 (5.4%), high myopia in one case (1.3%) and one child (1.3%) had no ocular pathology, just wishing to change eye color. 52 (71.2%) had medical indication, 9 (12.3%) had optical indication and 12 (16.4%) had cosmetic indication. Contact lenses were fitted in 103 eyes, the most tested lens was rigid gas permeable in 43 (41.7%), soft lens in 41 (39.8%) and cosmetic soft lens in 11 (10.6%). Aphakia was the most common diagnosis among children in use of contact lens. The incidence of medical indication was higher than the others and the most tested lens was the rigid gas permeable one.

  6. Modified suturing contact lens for penetrating keratoplasty.

    Science.gov (United States)

    Kramer, S G; Stewart, H L

    1978-11-01

    The authors have previously described a suturing contact lens that protects the corneal endothelium by aiding in the maintenance of the anterior chamber during penetrating keratoplasty. This report describes structural modifications of the suturing contact lens, which improve its stability and effectiveness. An additional configuration for use in corneal lacerations is presented.

  7. Developing students’ ideas about lens imaging: teaching experiments with an image-based approach

    Science.gov (United States)

    Grusche, Sascha

    2017-07-01

    Lens imaging is a classic topic in physics education. To guide students from their holistic viewpoint to the scientists’ analytic viewpoint, an image-based approach to lens imaging has recently been proposed. To study the effect of the image-based approach on undergraduate students’ ideas, teaching experiments are performed and evaluated using qualitative content analysis. Some of the students’ ideas have not been reported before, namely those related to blurry lens images, and those developed by the proposed teaching approach. To describe learning pathways systematically, a conception-versus-time coordinate system is introduced, specifying how teaching actions help students advance toward a scientific understanding.

  8. Multipurpose soft contact lens care in Japan

    Directory of Open Access Journals (Sweden)

    Toshida H

    2012-01-01

    Full Text Available Hiroshi Toshida1,2, Yoshiaki Kadota3, Chikako Suto2, Toshihiko Ohta1, Akira Murakami21Juntendo University Shizuoka Hospital, Department of Ophthalmology, Shizuoka, 2Juntendo University School of Medicine, Department of Ophthalmology, Tokyo, 3Bausch & Lomb Japan Co, Ltd, Research and Development, Tokyo, JapanPurpose: To assess the use of multipurpose lens care products via an online survey conducted among soft contact lens (SCL wearers in Japan.Methods: The subjects were 1000 men and women aged 15–44 years who reported that they cleaned their SCL by using multipurpose solution at least twice a week. Via the internet, they were asked questions about SCL care, the use of a rubbing step when cleaning SCL, cleaning and replacing lens cases, and recommended SCL care methods.Results: Of the 1000 SCL wearers enrolled, 94.3% performed lens care every day lenses were worn, 64.2% reported rubbing the lenses every time, 57.9% rubbed the lenses for at least 10 seconds per side, and 64.7% reported they rubbed the lenses on both sides. Further, 61.2% reported that they had been given an explanation of SCL cleaning at an eye clinic or contact lens store. Only 49.8% of subjects reported that they cleaned the lens case every time and 61.7% replaced the case within 3 months. Only 19.5% had been given an explanation about lens case care. Half of the subjects reported they had been given no recommendation to use specific SCL care products or could not remember whether or not they had. The most common reason for the recommendation was good compatibility with their type of lens.Conclusion: More education is needed in Japan regarding methods of SCL care to ensure correct lens cleaning with inclusion of a rubbing step, as well as sufficient cleaning and replacement of the lens case. Of particular interest is the finding that many subjects were not given an explanation about proper SCL care and lens case cleaning and replacement at the time of lens purchase or

  9. Tear Movement through a Contact Lens of Variable Thickness

    Science.gov (United States)

    Gerhart, Matthew; Anderson, Daniel

    2013-11-01

    This work is on a two-dimensional tear film with a movable porous contact lens. The inclusion of a contact lens into a tear film results in three layers: Pre-Lens Tear Film, Contact Lens, and the Post-Lens Tear Film layers. The interfaces between the contact lens and the tear films are modeled as planar interfaces. There is a free surface interface between the tear film and the outside air. The goal is analyze the effects of the spatial variability of thickness on the Post-Lens Tear Film thickness and on the fluid flow through the Contact Lens layer.

  10. A STUDY ON LENS-INDUCED GLAUCOMA

    Directory of Open Access Journals (Sweden)

    Savithiri Visvanathan

    2017-08-01

    Full Text Available BACKGROUND A study on factors in lens responsible, duration, time of interference and management of increased IOP in lens-induced glaucoma and estimation of aqueous protein level in lens-induced glaucoma. MATERIALS AND METHODS A randomised clinical trial on all cases of phacolytic and phacomorphic glaucoma seen in Coimbatore Medical College Hospital between January to December 2004. RESULTS In this study, males and females had equal prevalence. Out of 50, left eye was affected in 31 cases. Majority were phacolytic and phacomorphic glaucoma. The aqueous protein level was found to be high in lens-induced glaucoma. CONCLUSION Final visual recovery in lens-induced glaucoma is dependent on duration of glaucoma. ECCE or SICS with PCIOL is curative. If duration is more than 7 days, a trabeculectomy has to be added. Periodic checkup of fellow eye is indicated in all cases.

  11. Die klimaresiliente Gesellschaft - Transformation und Systemänderungen

    Science.gov (United States)

    Hirschfeld, Jesko; Hansen, Gerrit; Messner, Dirk

    Die Autoren erörtern die Zusammenhänge zwischen Klimaschutz und Anpassung an den Klimawandel, die Chancen, Risiken und Grenzen der Anpassung sowie den nationalen und globalen Transformationsbedarf. Neben den einzel- und volkswirtschaftlichen Auswirkungen des Klimawandels stellt das Kapitel auch die sozialen, politischen und ökologischen Auswirkungen in einen systemischen Zusammenhang. Die Autoren zeigen zudem, wie wichtig und schwierig räumliche und zeitliche Differenzierung sein kann. Auf nationaler Ebene stehen gesellschaftliche Akteure und politische Entscheidungsträger vor komplexen Analyse- und Steuerungsproblemen. Um Klimarisiken zu begegnen und Chancen der Klimaanpassung auszuschöpfen, müssen die verschiedenen Dimensionen wirtschaftlicher, sozialer, politischer und ökologischer Systeme, räumliche und zeitliche Skalenebenen berücksichtigt und Praxisakteure einbezogen werden.

  12. Using an adaptive expertise lens to understand the quality of teachers' classroom implementation of computer-supported complex systems curricula in high school science

    Science.gov (United States)

    Yoon, Susan A.; Koehler-Yom, Jessica; Anderson, Emma; Lin, Joyce; Klopfer, Eric

    2015-05-01

    Background: This exploratory study is part of a larger-scale research project aimed at building theoretical and practical knowledge of complex systems in students and teachers with the goal of improving high school biology learning through professional development and a classroom intervention. Purpose: We propose a model of adaptive expertise to better understand teachers' classroom practices as they attempt to navigate myriad variables in the implementation of biology units that include working with computer simulations, and learning about and teaching through complex systems ideas. Sample: Research participants were three high school biology teachers, two females and one male, ranging in teaching experience from six to 16 years. Their teaching contexts also ranged in student achievement from 14-47% advanced science proficiency. Design and methods: We used a holistic multiple case study methodology and collected data during the 2011-2012 school year. Data sources include classroom observations, teacher and student surveys, and interviews. Data analyses and trustworthiness measures were conducted through qualitative mining of data sources and triangulation of findings. Results: We illustrate the characteristics of adaptive expertise of more or less successful teaching and learning when implementing complex systems curricula. We also demonstrate differences between case study teachers in terms of particular variables associated with adaptive expertise. Conclusions: This research contributes to scholarship on practices and professional development needed to better support teachers to teach through a complex systems pedagogical and curricular approach.

  13. [Contact lens related corneal ulcers: clinical, microbiological and therapeutic features].

    Science.gov (United States)

    Benhmidoune, L; Bensemlali, A; Bouazza, M; Karami, R; El Mansouri, H; El Belhadji, M; Rachid, R; Chakib, A; Amraoui, A

    2013-09-01

    Corneal ulcers in contact lens wearers are becoming more common, and can sometimes lead to severe complications. The purpose of this study is to define the epidemiological, clinical, microbiological and therapeutic considerations of these ulcers within the above context. We conducted an uncontrolled, descriptive, retrospective study of 51 patients presenting with contact lens related corneal ulcers to the ophthalmology department of the August 20, 1953 Hospital in Casablanca between January 2009 and January 2012. The average age of our patients was 22 years, with a gender ratio of 7.5 female to male. General risk factors (diabetes and tuberculosis) were found in 17.5% of cases. The average length of hospital stay was 15 days. Of our patients, 58.8% wore cosmetic contact lenses and 41.18% wore therapeutic contact lenses. Mean duration prior to consultation was 5 days. The predominant clinical signs were eye pain and redness, with a decrease in visual acuity worse than 1/10 in 82.3% of patients. In 70.6% of cases, the ulcer was central. The average size was 4.3mm. An anterior chamber reaction was found in 47.1%. Corneal bacterial cultures were positive in 47.8%. Pathogens found were Staphylococcus aureus, Pseudomonas aeruginosa and Acanthamœba. Contact lens and solution cultures were positive in 73.6% of cases. Outcomes were favorable with local and systemic antibiotic treatment adapted to microbiological results in only 41.2% of cases. In the remaining patients, significant secondary opacities persisted. Cosmetic and therapeutic contact lens wear is a major cause of corneal ulcer. Delayed consultation results in severe sequelae with persistently decreased visual acuity. The ophthalmologist plays an important role in preventing complications of contact lens wear, through better hygiene instruction and follow-up of his or her patients. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  14. Design method of freeform light distribution lens for LED automotive headlamp based on DMD

    Science.gov (United States)

    Ma, Jianshe; Huang, Jianwei; Su, Ping; Cui, Yao

    2018-01-01

    We propose a new method to design freeform light distribution lens for light-emitting diode (LED) automotive headlamp based on digital micro mirror device (DMD). With the Parallel optical path architecture, the exit pupil of the illuminating system is set in infinity. Thus the principal incident rays of micro lens in DMD is parallel. DMD is made of high speed digital optical reflection array, the function of distribution lens is to distribute the emergent parallel rays from DMD and get a lighting pattern that fully comply with the national regulation GB 25991-2010.We use DLP 4500 to design the light distribution lens, mesh the target plane regulated by the national regulation GB 25991-2010 and correlate the mesh grids with the active mirror array of DLP4500. With the mapping relations and the refraction law, we can build the mathematics model and get the parameters of freeform light distribution lens. Then we import its parameter into the three-dimensional (3D) software CATIA to construct its 3D model. The ray tracing results using Tracepro demonstrate that the Illumination value of target plane is easily adjustable and fully comply with the requirement of the national regulation GB 25991-2010 by adjusting the exit brightness value of DMD. The theoretical optical efficiencies of the light distribution lens designed using this method could be up to 92% without any other auxiliary lens.

  15. Temporal properties of the lens eyes of the box jellyfish Tripedalia cystophora

    DEFF Research Database (Denmark)

    O'Connor, Megan; Nilsson, Dan-E; Garm, Anders Lydik

    2010-01-01

    Box jellyWsh (Cubomedusae) are visually orientating animals which posses a total of 24 eyes of 4 morphological types; 2 pigment cup eyes (pit eye and slit eye) and 2 lens eyes [upper lens-eye (ule) and lower lens-eye (lle)]. In this study, we use electroretinograms (ERGs) to explore temporal...... properties of the two lens eyes. We Wnd that the ERG of both lens eyes are complex and using sinusoidal Xicker stimuli we Wnd that both lens eyes have slow temporal resolution. The average Xicker fusion frequency (FFF) was found to be approximately 10 Hz for the ule and 8 Hz for the lle. Di......Verences in the FFF and response patterns between the two lens eyes suggest that the ule and lle Wlter information diVerently in the temporal domain and thus are tuned to perform diVerent visual tasks. The data collected in this study support the idea that the visual system of box jellyWsh is a collection of special...

  16. Wind lens technology and its application to wind and water turbine and beyond

    Directory of Open Access Journals (Sweden)

    Ohya Yuji

    2017-01-01

    Full Text Available Wind lens is a new type of wind power system consisting of a simple brimmed ring structure that surrounds the rotor causing greater wind to pass through the turbine. As a consequence, the turbine's efficiency of capturing energy from the wind gets dramatically increased. A Wind lens turbine can generate 2–5 times the power of an existing wind turbine given at the same rotor diameter and incoming wind speed. This fluid dynamical effect is also effective in the water. We have developed 1–3 kW Wind lens turbines and a 100 kW Wind lens turbine. In addition to the enhanced output power, Wind lens turbine is quiet. The technology is now used in an offshore experiment with a hexagonal float 18 meters in diameter set off the coast of Hakata Bay in Fukuoka City. Moreover, we are now pursuing larger size Wind lens turbines through multi-rotor design consisting of multiple Wind lens turbines in a same vertical plane to embody larger total power output.

  17. Development of a Novel Embedded Relay Lens Microscopic Hyperspectral Imaging System for Cancer Diagnosis: Use of the Mice with Oral Cancer to Be the Example

    Directory of Open Access Journals (Sweden)

    Yao-Fang Hsieh

    2012-01-01

    the fluorescence of cells or tissue can provide the characteristic signature for identification of normal and abnormal. In this work, the development of the ERL-MHSI system is discussed and the capability of the system is demonstrated by diagnosing early stage oral cancer of twenty mice in vitro. The best sensitivity for identifying normal cells and squamous cell carcinoma (SCC was 100%. The best specificity for identifying normal cells and SCC was 99%. The best sensitivity for identifying normal cells and dysplasia was 99%. The best specificity for identifying normal cells and dysplasia was 97%. This work also utilizes fractal dimension to analyze the morphological information and find the significant different values between normal and SCC.

  18. Noncontact optical measurement of lens capsule thickness ex vivo

    Science.gov (United States)

    Ziebarth, Noel M.; Manns, Fabrice; Uhlhorn, Stephen; Parel, Jean-Marie

    2004-07-01

    Purpose: To design a non-contact optical system to measure lens capsule thickness in cadaver eyes. Methods: The optical system uses a 670nm laser beam delivered to a single-mode fiber coupler. The output of the fiber coupler is focused onto the tissue using an aspheric lens (NA=0.68) mounted on a motorized translation stage. Light reflected from the sample is collected by the fiber coupler and sent to a silicon photodiode connected to a power meter. Peaks in the power signal are detected when the focal point of the aspheric lens coincides with the capsule boundaries. The capsule thickness is proportional to the distance between successive peaks. Anterior and posterior lens capsule thickness measurements were performed on 13 human, 10 monkey, and 34 New Zealand white rabbit lenses. The cadaver eyes were prepared for optical measurements by bonding a PMMA ring on the sclera. The posterior pole was sectioned, excess vitreous was removed, and the eye was placed on a Teflon slide. The cornea and iris were then sectioned. After the experiments, the lenses were excised, placed in 10% buffered formalin, and prepared for histology. Results: Central anterior lens capsule thickness was 9.4+/-2.9μm (human), 11.2+/-6.6μm (monkey), and 10.3+/-3.6μm (rabbit) optically and 14.9+/-1.6μm (human), 17.7+/-4.9μm (monkey), and 12.6+/-2.3μm (rabbit) histologically. The values for the central posterior capsule were 9.4+/-2.9μm (human), 6.6+/-2.5μm (monkey), and 7.9+/-2.3μm (rabbit) optically and 4.6+/-1.4μm (human), 4.5+/-1.2μm (monkey), and 5.7+/-1.7μm (rabbit) histologically. Conclusions: This study demonstrates that a non-contact optical system can successfully measure lens capsule thickness in cadaver eyes.

  19. Microbial contamination of contact lens storage cases and domestic tap water of contact lens wearers.

    Science.gov (United States)

    Üstüntürk, Miray; Zeybek, Zuhal

    2012-11-01

    Contact lenses have been widely used as an alternative to spectacles both in developed and developing countries. However, under certain circumstances, adverse responses can occur during contact lens wear and several microorganisms--including bacteria, fungi, and free living amoebae--can cause several eye infections in wearers. Extended wear of contact lenses is the major risk factor of eye infections such as microbial keratitis, besides contaminated contact lens storage case, contaminated lens care solutions, and inaccurate contact lens handling. In this study, we collected contact lens storage case and domestic tap water samples from 50 asymptomatic contact lens wearers. We determined that total aerobic mesophilic bacteria were isolated in 45 (90 %), Gram negative rod bacteria were isolated in 20 (40 %), Pseudomonas spp. were isolated in 2 (4 %) and fungi were isolated in 18 (36 %) out of 50 contact lens storage cases. Free living amoebae were not detected in investigated contact lens storage cases. At the same time, out of 50, total aerobic mesophilic bacteria were isolated in 34 (68 %), fungi were isolated in 15 (30 %) and free living amoebae were isolated in 15 (30 %) domestic tap water samples. No Gram-negative rod bacteria and Pseudomonas spp. were detected in investigated water samples. Two contact lens case samples and two tap water samples were excluded from the analysis for Pseudomonas spp. for technical reasons. According to our findings, inadequate contact lens maintenance during lens wear may result in the contamination of contact lens storage cases. This situation can lead to severe eye infections in contact lens wearers over time.

  20. Overlapped illusion optics: a perfect lens brings a brighter feature

    Science.gov (United States)

    Xu, Yadong; Du, Shengwang; Gao, Lei; Chen, Huanyang

    2011-02-01

    In this paper, we show that a perfect lens can be employed to make multiple objects appear like only one object in the far field, leading to a new concept in illusion optics. Numerical simulations have been performed to verify the functionalities for both passive and active objects. The conceptual device can be utilized to enhance the illumination brightness for both incoherent and coherent systems.

  1. Overlapped illusion optics: a perfect lens brings a brighter feature

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yadong; Gao Lei; Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Du Shengwang, E-mail: kenyon@ust.hk [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2011-02-15

    In this paper, we show that a perfect lens can be employed to make multiple objects appear like only one object in the far field, leading to a new concept in illusion optics. Numerical simulations have been performed to verify the functionalities for both passive and active objects. The conceptual device can be utilized to enhance the illumination brightness for both incoherent and coherent systems.

  2. The Director's Lens: An Intelligent Assistant for Virtual Cinematography

    OpenAIRE

    Lino, Christophe; Christie, Marc; Ranon, Roberto; Bares, William

    2011-01-01

    International audience; We present the Director's Lens, an intelligent interactive assistant for crafting virtual cinematography using a motion-tracked hand-held device that can be aimed like a real camera. The system employs an intelligent cinematography engine that can compute, at the request of the fi lmmaker, a set of suitable camera placements for starting a shot. These suggestions represent semantically and cinematically distinct choices for visualizing the current narrative. In computi...

  3. A Multibeam Antenna Array Based on Printed Rotman Lens

    OpenAIRE

    Wang Zongxin; Xiang Bo; Yang Fei

    2013-01-01

    A compact printable multibeam antenna array is studied in this paper. The antenna system is composed of a printed Rotman lens and an antipodal dual elliptically tapered slot antenna array; both of the two components are studied, respectively, at first, and then integrated on a single printed circuit board to make up the integrated unit of the multibeam antenna array. Measured results of all components are presented.

  4. Contact lens interactions with the tear film.

    Science.gov (United States)

    Mann, Aisling; Tighe, Brian

    2013-12-01

    Biochemical changes brought about by the influence of the contact lens on the tear film are conveniently split into two categories. Firstly, the lens can remove or reduce the levels of specific components in the tear film, and secondly, the lens can augment the tear film, by stimulating the influx of new components or increasing the level of existing components. The most obvious tear film components for study in this context are lipids, proteins, mucins and electrolytes. The interactions are affected by the properties of the lens, the characteristics of the individual wearer and the wear schedule. An additional complicating factor is the fact that the lens is many times thicker than the tear film and any immobilised tear components will be more extensively exposed to oxygen and UV radiation than is the case in the absence of a lens. It is arguably the lipoidal components that are most markedly affected by lens wear, since their immobilisation on the lens surface markedly increases their susceptibility to autoxidative degradation. The limited information that is available highlights the importance of subject specificity and suggests that lipid oxidation phenomena are potentially important in contributing to the 'end of day' discomfort of symptomatic contact lens patients. It is clear that tear lipids, although regarded as relatively inert for many years, are now seen as a reactive and potentially important family of compounds in the search for understanding of contact lens-induced discomfort. The influence of the lens on tear proteins shows the greatest range of complexity. Deposition and denaturation can stimulate immune response, lower molecular weight proteins can be extensively absorbed into the lens matrix and the lens can stimulate cascade or upregulation processes leading either to the generation of additional proteins and peptides or an increase in concentration of existing components. Added to this is the stimulating influence of the lens on vascular

  5. Estimating rice yield related traits and quantitative trait loci analysis under different nitrogen treatments using a simple tower-based field phenotyping system with modified single-lens reflex cameras

    Science.gov (United States)

    Naito, Hiroki; Ogawa, Satoshi; Valencia, Milton Orlando; Mohri, Hiroki; Urano, Yutaka; Hosoi, Fumiki; Shimizu, Yo; Chavez, Alba Lucia; Ishitani, Manabu; Selvaraj, Michael Gomez; Omasa, Kenji

    2017-03-01

    Application of field based high-throughput phenotyping (FB-HTP) methods for monitoring plant performance in real field conditions has a high potential to accelerate the breeding process. In this paper, we discuss the use of a simple tower based remote sensing platform using modified single-lens reflex cameras for phenotyping yield traits in rice under different nitrogen (N) treatments over three years. This tower based phenotyping platform has the advantages of simplicity, ease and stability in terms of introduction, maintenance and continual operation under field conditions. Out of six phenological stages of rice analyzed, the flowering stage was the most useful in the estimation of yield performance under field conditions. We found a high correlation between several vegetation indices (simple ratio (SR), normalized difference vegetation index (NDVI), transformed vegetation index (TVI), corrected transformed vegetation index (CTVI), soil-adjusted vegetation index (SAVI) and modified soil-adjusted vegetation index (MSAVI)) and multiple yield traits (panicle number, grain weight and shoot biomass) across a three trials. Among all of the indices studied, SR exhibited the best performance in regards to the estimation of grain weight (R2 = 0.80). Under our tower-based field phenotyping system (TBFPS), we identified quantitative trait loci (QTL) for yield related traits using a mapping population of chromosome segment substitution lines (CSSLs) and a single nucleotide polymorphism data set. Our findings suggest the TBFPS can be useful for the estimation of yield performance during early crop development. This can be a major opportunity for rice breeders whom desire high throughput phenotypic selection for yield performance traits.

  6. Anterior chamber intra ocular lens implantation.

    OpenAIRE

    Raju N

    1989-01-01

    The role of A.C. IOL in modern implant surgery has become somewhat debatable, since, the choice procedure to day is undoubtedly an ECCE with a PC lens implant preferably in the capsular bag. Even so, anterior chamber lens implantation has its definite indications. As such it is necessary for the implant surgeon to be familiar with the latest technique in this modality of surgery as well. Many of the complications of earlier rigid model AC IOLs were mainly due to defective lens design. With th...

  7. Automated Micro-Object Detection for Mobile Diagnostics Using Lens-Free Imaging Technology

    Directory of Open Access Journals (Sweden)

    Mohendra Roy

    2016-05-01

    Full Text Available Lens-free imaging technology has been extensively used recently for microparticle and biological cell analysis because of its high throughput, low cost, and simple and compact arrangement. However, this technology still lacks a dedicated and automated detection system. In this paper, we describe a custom-developed automated micro-object detection method for a lens-free imaging system. In our previous work (Roy et al., we developed a lens-free imaging system using low-cost components. This system was used to generate and capture the diffraction patterns of micro-objects and a global threshold was used to locate the diffraction patterns. In this work we used the same setup to develop an improved automated detection and analysis algorithm based on adaptive threshold and clustering of signals. For this purpose images from the lens-free system were then used to understand the features and characteristics of the diffraction patterns of several types of samples. On the basis of this information, we custom-developed an automated algorithm for the lens-free imaging system. Next, all the lens-free images were processed using this custom-developed automated algorithm. The performance of this approach was evaluated by comparing the counting results with standard optical microscope results. We evaluated the counting results for polystyrene microbeads, red blood cells, and HepG2, HeLa, and MCF7 cells. The comparison shows good agreement between the systems, with a correlation coefficient of 0.91 and linearity slope of 0.877. We also evaluated the automated size profiles of the microparticle samples. This Wi-Fi-enabled lens-free imaging system, along with the dedicated software, possesses great potential for telemedicine applications in resource-limited settings.

  8. Assessment of Malawi’s success in child mortality reduction through the lens of the Catalytic Initiative Integrated Health Systems Strengthening programme: Retrospective evaluation

    Directory of Open Access Journals (Sweden)

    Tanya Doherty

    2015-12-01

    Full Text Available Malawi is estimated to have achieved its Millennium Development Goal (MDG 4 target. This paper explores factors influencing progress in child survival in Malawi including coverage of interventions and the role of key national policies. We performed a retrospective evaluation of the Catalytic Initiative (CI programme of support (2007–2013. We developed estimates of child mortality using four population household surveys undertaken between 2000 and 2010. We recalculated coverage indicators for high impact child health interventions and documented child health programmes and policies. The Lives Saved Tool (LiST was used to estimate child lives saved in 2013. The mortality rate in children under 5 years decreased rapidly in the 10 CI districts from 219 deaths per 1000 live births (95% confidence interval (CI 189 to 249 in the period 1991–1995 to 119 deaths (95% CI 105 to 132 in the period 2006–2010. Coverage for all indicators except vitamin A supplementation increased in the 10 CI districts across the time period 2000 to 2013. The LiST analysis estimates that there were 10 800 child deaths averted in the 10 CI districts in 2013, primarily attributable to the introduction of the pneumococcal vaccine (24% and increased household coverage of insecticide–treated bednets (19%. These improvements have taken place within a context of investment in child health policies and scale up of integrated community case management of childhood illnesses. Malawi provides a strong example for countries in sub–Saharan Africa of how high impact child health interventions implemented within a decentralised health system with an established community–based delivery platform, can lead to significant reductions in child mortality.

  9. 16 CFR 315.6 - Expiration of contact lens prescriptions.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Expiration of contact lens prescriptions. 315.6 Section 315.6 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS CONTACT LENS RULE § 315.6 Expiration of contact lens prescriptions. (a) In general. A contact lens prescription shall expire: (1) On the date...

  10. 21 CFR 886.5844 - Prescription spectacle lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Prescription spectacle lens. 886.5844 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5844 Prescription spectacle lens. (a) Identification. A prescription spectacle lens is a glass or plastic device that is a lens intended to be worn by...

  11. Modeling of the Autofluorescence Spectra of the Crystalline Lens with Cataract Taking into Account Light Scattering

    Science.gov (United States)

    Shapovalov, K. A.; Salmin, V. V.; Lazarenko, V. I.; Gar‧kavenko, V. V.

    2017-05-01

    The model of the autofluorescence spectrum formation of a crystalline lens taking into account light scattering was presented. Cross sections of extinction, scattering and absorption were obtained numerically for models of normal crystalline lens and cataract according to the Mie theory for polydisperse systems. To validate the model, data on the autofluorescence spectra of the normal lens and cataracts were obtained using an experimental ophthalmologic spectrofluorometer with excitation by UV light emitting diodes. In the framework of the model, the influence of the lens light scattering on the shape of the luminescence spectrum was estimated. It was found that the changes in the fluorescence spectrum of lenses with cataracts can be completely interpreted by the light scattering.

  12. Contact lens compliance among a group of young, university-based lens users in South India.

    Science.gov (United States)

    Noushad, Babu; Saoji, Yeshwant; Bhakat, Premjit; Thomas, Jyothi

    2012-01-01

    To investigate the rate of compliance with the soft contact lens care and maintenance procedures with a focus on contact lens wearing habits, cleaning and disinfecting procedures, and maintenance of lens care accessories in a group of young, university-based contact lens wearers Two hundred and sixteen young soft contact lens wearers with an age range of 18-22 years were selected conveniently from the student population of Manipal University, Manipal, India. After receiving informed consent from the participants, their level of compliance with contact lenses was assessed using a questionnaire. The mean (±SD) age of the participants was 21.86±2.35 years. Out of 216 subjects, only 34% of the lens users were identified to be compliant with the least level of compliance observed in the maintenance of lens care accessories. Conventional users showed significantly (p=0.001) better level of compliance compared to disposable wearers and so did the users who acquired their lenses from clinicians (p=0.001) compared to over-the-counter lens receipt. The gender (p=0.496) and years of experience in contact lens use (p=0.142) did not show any statistically significant difference in the level of compliance. This study demonstrated that non-compliance with lens care procedures among a group of young, university-based soft contact lens wearers is common. The results indicated that all subjects had some degree of non-compliance and the least level of compliance observed in the care of lens accessories.

  13. Tear film physiology and contact lens wear. II. Contact lens-tear film interaction.

    Science.gov (United States)

    Holly, F J

    1981-04-01

    The successful fitting of contact lenses requires the practitioner to take into account many properties of the specific lens type used but the practitioner must also understand patient factors including tear properties, use of appropriate solutions, procedures for lens cleaning, and efficiency of blinking. Selection of appropriate patients, selection of lens type, proper fitting, good maintenance, and training and monitoring of patients increase the probability of achieving success.

  14. The tensegrity model applied to the lens: a hypothesis for the presence of the fiber cell ball and sockets.

    Science.gov (United States)

    Yamada, T; Richiert, D; Tumminia, S J; Russell, P

    2000-07-01

    The concept of tensegrity refers to the tensional integrity of a system. Such a system mechanically stabilizes itself by balancing the opposing forces of tension and compression. One category of this model involves a 'pre-stressed' condition in which the structural elements are in a state of tensional compression. The other category includes rigid struts that can sustain the opposing forces. The lens of the eye contains epithelial cells that differentiate at the lens equator to fiber cells. With time, these fiber cells are packed into the center of the lens or the lens nucleus. Part of the process of differentiation is the loss of the cellular nucleus and organelles. During maturation of the lens fiber cells, much of the cytoskeleton is lost as a result of proteolysis. As the lens cells mature, ball and socket joints and interlocking ridges appear on the cellular surface. Applying the tensegrity model to the lens, it appears that the lens cells go from prestressed state of tensional compression to the other state that is defined by rigid connections between cells.

  15. Bionic intraocular lens with variable focus and integrated structure

    Science.gov (United States)

    Liang, Dan; Wang, Xuan-Yin; Du, Jia-Wei; Xiang, Ke

    2015-10-01

    This paper proposes a bionic accommodating intraocular lens (IOL) for ophthalmic surgery. The designed lens has a solid-liquid mixed integrated structure, which mainly consists of a support ring, elastic membrane, rigid lens, and optical liquid. The lens focus can be adjusted through the deformation of the lens front surface when compressed. The integrated structure of the IOL is presented, as well as a detailed description of the lens materials and fabrication process. Images under different radial pressures are captured, and the lens deformation process, accommodating range, density, and optical property are analyzed. The designed lens achieves a 14.6 D accommodating range under a radial pressure of 51.4 mN and a 0.24 mm alteration of the lens outer radius. The deformation property of the lens matches well with the characteristic of the eye and shows the potential to help patients fully recover their vision accommodation ability after the cataract surgery.

  16. Generalized Alvarez lens for correction of laser aberrations

    Energy Technology Data Exchange (ETDEWEB)

    LaFortune, K N

    2004-12-02

    The Alvarez lens (US Patent No. 3,305,294 [1]) is a compact aberration corrector. The original design emphasized in the patent consists of a pair of adjacent optical elements that provide a variable focus. A lens system with a variable effective focal length is nothing new. Such systems are widely used in cameras, for example. It is the compactness and simplicity of operation that is the key advantage of the Alvarez lens. All of the complexity is folded into the design and fabrication of the optical elements. As mentioned in the Alvarez patent [1] and elaborated upon in Palusinski et al. [2], if one is willing to fold even more complexity into the optical elements, it is possible to correct higher-order aberrations as well. There is no theoretical limit to the number or degree of wavefront distortions that can be corrected. The only limitation is that there must be a fixed relative magnitude of the aberrations. Independent correction of each component of the higher-order aberrations can not be performed without additional elements and degrees of freedom [3]. Under some circumstances, coupling may be observed between different aberrations. This can be mitigated with the appropriate choice of design parameters. New methods are available today that increase the practicality of making higher-order aberration correctors [4,5,6].

  17. CMU DeepLens: deep learning for automatic image-based galaxy-galaxy strong lens finding

    Science.gov (United States)

    Lanusse, François; Ma, Quanbin; Li, Nan; Collett, Thomas E.; Li, Chun-Liang; Ravanbakhsh, Siamak; Mandelbaum, Rachel; Póczos, Barnabás

    2018-01-01

    Galaxy-scale strong gravitational lensing can not only provide a valuable probe of the dark matter distribution of massive galaxies, but also provide valuable cosmological constraints, either by studying the population of strong lenses or by measuring time delays in lensed quasars. Due to the rarity of galaxy-scale strongly lensed systems, fast and reliable automated lens finding methods will be essential in the era of large surveys such as Large Synoptic Survey Telescope, Euclid and Wide-Field Infrared Survey Telescope. To tackle this challenge, we introduce CMU DeepLens, a new fully automated galaxy-galaxy lens finding method based on deep learning. This supervised machine learning approach does not require any tuning after the training step which only requires realistic image simulations of strongly lensed systems. We train and validate our model on a set of 20 000 LSST-like mock observations including a range of lensed systems of various sizes and signal-to-noise ratios (S/N). We find on our simulated data set that for a rejection rate of non-lenses of 99 per cent, a completeness of 90 per cent can be achieved for lenses with Einstein radii larger than 1.4 arcsec and S/N larger than 20 on individual g-band LSST exposures. Finally, we emphasize the importance of realistically complex simulations for training such machine learning methods by demonstrating that the performance of models of significantly different complexities cannot be distinguished on simpler simulations. We make our code publicly available at https://github.com/McWilliamsCenter/CMUDeepLens.

  18. Bilateral lens luxation and intracapsular lens extractions in a Matshchie's tree kangaroo.

    Science.gov (United States)

    McLean, Nancy Johnstone; Zimmerman, Ralph

    2015-01-01

    An adult, female, captive, Matshchie's tree kangaroo was diagnosed with an anterior lens luxation in the right eye and a lens subluxation in the left eye. Both eyes were treated surgically with intracapsular lens extractions. A 360° rhegmatogenous retinal detachment was diagnosed 6 months postoperatively in the left eye. Aphakic vision was maintained in the right eye 9 months postoperatively. Based on family history and the lack of antecedent ocular disease, the lens luxations were presumed to be inherited and veterinarians should be aware of this condition within the captive tree kangaroo population. © 2014 American College of Veterinary Ophthalmologists.

  19. Optical design used in Z-stack imaging based on liquid lens

    Science.gov (United States)

    Yang, Tianling; Wang, Liqiang; Duan, Huilong

    2010-11-01

    Z-stack imaging system drives microscope to scan one image plane, changes the depth of the focus, and then scans another plane, last gets the data of examination sample. The curvature of liquid lens can be changed according to changes in the characteristics of voltage. It leads to achieve miniaturization and simply structure of focus imaging system. This article uses CODE V to design a microscope objective which employs an Arctic 416 liquid lens. It proposes architecture of 5 groups of lens with 40× microscope objective lens, 0.65 numeral aperture and 0.52° field of view (FOV). By CODE V automatic design, the microscope objective lens achieves a continuous focus adjusting up to 120μm depth. And then a better FOV MTF value with the same continuous focus range can be obtained by reducing one of lens group. Lastly, by replacing the high performance material of glass, the FOV achieves higher MTF and the continuous focus range increases to 130μm.

  20. A look through 'lens' cubic mitochondria.

    Science.gov (United States)

    Almsherqi, Zakaria; Margadant, Felix; Deng, Yuru

    2012-10-06

    Cell membranes may fold up into three-dimensional nanoperiodic cubic structures in biological systems. Similar geometries are well studied in other disciplines such as mathematics, physics and polymer chemistry. The fundamental function of cubic membranes in biological systems has not been uncovered yet; however, their appearance in specialized cell types indicates a role as structural templates or perhaps direct physical entities with specialized biophysical properties. The mitochondria located at the inner segment of the retinal cones of tree shrew (Tupaia glis and Tupaia belangeri) contain unique patterns of concentric cristae with a highly ordered membrane arrangement in three dimensions similar to the photonic nanostructures observed in butterfly wing scales. Using a direct template matching method, we show that the inner mitochondrial membrane folds into multi-layered (8 to 12 layers) gyroid cubic membrane arrangements in the photoreceptor cells. Three-dimensional simulation data demonstrate that such multi-layer gyroid membrane arrangements in the retinal cones of a tree shrew's eye can potentially function as: (i) multi-focal lens; (ii) angle-independent interference filters to block UV light; and (iii) a waveguide photonic crystal. These theoretical results highlight for the first time the significance of multi-layer cubic membrane arrangements to achieve near-quasi-photonic crystal properties through the simple and reversible biological process of continuous membrane folding.

  1. The lens, cataracts and space-related radiations

    Science.gov (United States)

    Worgul, B.

    Of considerable moment in the annals of space-related radiation studies is the recent report of radiogenic cataracts among the astronauts (Cucinotta et al., 2002. Rad. Res. 156: 460). Although generally unexpected, the finding was fully predicted by a number of experimental studies on high LET radiation cataractogenesis. Historically, the lens and its primary pathology, cataract, have played important roles in the elucidation of the nuances of the biological response to ioniz ing radiation. So too their study has contributed greatly to an appreciation of the cell and tissue effects of exposure to high - LET radiation . Findings from cataract studies have validated, at the level of complex tissue expression, evidence for extremely large RBEs at low doses and the inverse dose-rate effect observed in other systems. The extensive experiment al studies on radiation cataractogenesis in rodents presaged and predicted the recent report of radiogenic cataracts in the astronaut corps. It is therefore important to revisit and re-evaluate the existing experimental data on lens damage following high-LET radiation exposure. Also given the circumstances, the tissue without question deserves continued investigative exploitation and scrutiny. In addition greater attention should be paid to the potential the lens as a surrogate for tissues less amenable to non - invasive longitudinal examination. Currently the lens and cataract studies are again providing insights into fundamental biological processes while at the same time establishing additional bases for medical follow-up. Among the highly relevant studies are our recent findings which support the concept of a genetic predisposition to radiation sensitivity. Individuals with elevated radiation sensitivity may not be appropriate choices for manned forays into space. Also of particular concern is the potentially complicating influence of the bystander effect/adaptive response for determining risk of developing cataracts from space

  2. Comparison of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbits

    Directory of Open Access Journals (Sweden)

    Hong Yan

    2017-02-01

    Full Text Available AIM: To compare of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbit. METHODS: Sixteen New Zealand rabbits (2.4-2.5 kg were randomly divided into two groups (Group A, n=12; Group B, n=4. In Group A, the right eyes were treated with vitrectomy and systemic hyperoxia (oxygen concentration: 80%-85%, 1 ATA, 4h/d (Group A-right, and the left eyes were treated with hyperoxia without vitrectomy surgery (Group A-left. Four rabbits in group B (eight eyes were untreated as the controls. Lens transparency was monitored with a slit lamp and recorded before and after vitrectomy. After hyperoxic treatment for 6mo, the eyeballs were removed and the lens cortices (containing the capsules and nuclei were separated for further morphological and biochemical evaluation. RESULTS: Six months after treatments, there were no significant morphological changes in the lenses in any experimental group when observed with a slit lamp. However, the levels of water-soluble proteins and ascorbate, and the activities of catalase and Na+-K+-ATPase were significantly reduced, whereas the levels of malondialdehyde and transforming growth factor β2 (TGF-β2 were significantly elevated, in both the cortices and nuclei of eyes treated with vitrectomy and hyperoxia. The increase in protein-glutathione mixed disulfides and the reduction in water-soluble proteins were more obvious in the lens nuclei. The levels of ascorbate in the vitreous fluid were also reduced after vitrectomy, whereas TGF-β2 increased after vitrectomy and hyperoxia. Systemic hyperoxia exposure increased these effects. CONCLUSION: Removal of the intact vitreous gel with vitrectomy and exposing the lens to increased oxygen from the retina induce lens oxidation and aggregation. Thus, an intact vitreous gel structure may protect the lens from oxidative insult and maintain lens transparency.

  3. The Charles F. Prentice award lecture 2009: Crystalline lens research and serendipity in science.

    Science.gov (United States)

    Sivak, Jacob Gershon

    2010-09-01

    Whether it is called serendipity or creativity, the process of scientific discovery is not one that lends itself to advance planning or programming, nor does it lend itself to an emphasis solely on applied research, research with industrial partners, or large teams of researchers because researchers must rely on intuition and the capacity to move quickly in new directions. Studies in my laboratory began with efforts to relate lens embryonic development to lens optical performance in a variety of vertebrate species. The initial direction concerned the optics of the fish eye, a system in which a spherical lens is essentially the only refractive component of the eye and one in which accommodation takes place by means of lens movement. This in turn led to an interest in how amphibious animals cope with the refractive transition that takes place when moving from air to water and vice versa. The development of a super accommodative ability in some diving birds is one adaptation that was explored. These curiosity-driven efforts led in turn to the development of a scanning laser system that provided a tool that can be used to evaluate the process of cataract development, either on the basis of in vivo exposure to chemicals or electromagnetic radiation and subsequent analysis of the excised lens or to the in vitro study of the lens in long-term whole lens culture experiments. The same approach has also been used as an in vitro ocular toxicology assay to develop sensitive in vitro methods to reduce regulatory dependence on the use of live animals. Finally, these applied directions in turn created new basic knowledge concerning the morphology and physiology of eye tissue organelles, particularly the morphology, distribution, and dynamic properties of the mitochondria found in the lens and in the retinal pigment epithelium.

  4. Contractual considerations in contact lens practice.

    Science.gov (United States)

    Classé, J G

    1986-03-01

    The use of forms in contact lens practice can save time, promote patient education, and reduce the opportunity for legal or economic disputes. The most commonly employed forms are those for contact lens fitting agreements, instructions for care and maintenance of lenses, prepaid service agreements, clinical investigations of investigatory lenses or solutions, and for extended wear patients. Sample forms are utilized for purposes of illustration.

  5. Acoustic lens for capacitive micromachined ultrasonic transducers

    Science.gov (United States)

    Chang, Chienliu; Firouzi, Kamyar; Park, Kwan Kyu; Sarioglu, Ali Fatih; Nikoozadeh, Amin; Yoon, Hyo-Seon; Vaithilingam, Srikant; Carver, Thomas; Khuri-Yakub, Butrus T.

    2014-08-01

    Capacitive micromachined ultrasonic transducers (CMUTs) have great potential to compete with traditional piezoelectric transducers in therapeutic ultrasound applications. In this paper we have designed, fabricated and developed an acoustic lens formed on the CMUT to mechanically focus ultrasound. The acoustic lens was designed based on the paraxial theory and made of silicone rubber for acoustic impedance matching and encapsulation. The CMUT was fabricated based on the local oxidation of silicon (LOCOS) and fusion-bonding. The fabricated CMUT was verified to behave like an electromechanical resonator in air and exhibited wideband response with a center frequency of 2.2 MHz in immersion. The fabrication for the acoustic lens contained two consecutive mold castings and directly formed on the surface of the CMUT. Applied with ac burst input voltages at the center frequency, the CMUT with the acoustic lens generated an output pressure of 1.89 MPa (peak-to-peak) at the focal point with an effective focal gain of 3.43 in immersion. Compared to the same CMUT without a lens, the CMUT with the acoustic lens demonstrated the ability to successfully focus ultrasound and provided a viable solution to the miniaturization of the multi-modality forward-looking endoscopes without electrical focusing.

  6. Trends in US Contact Lens Prescribing 2002 to 2014.

    Science.gov (United States)

    Efron, Nathan; Nichols, Jason J; Woods, Craig A; Morgan, Philip B

    2015-07-01

    To document contact lens prescribing patterns in the United States between 2002 and 2014. A survey of contact lens prescribing trends was conducted each year between 2002 and 2014, inclusive. Randomly selected contact lens practitioners were asked to provide information relating to 10 consecutive contact lens fits between January and March each year. Over the 13-year survey period, 1650 survey forms were received from US practitioners representing details of 7702 contact lens fits. The mean (±SD) age of lens wearers was 33.6 (±15.2) years, of whom 65.2% were female. Rigid lens new fits decreased from 13.0% in 2002 to 9.4% in 2014. Across this period, silicone hydrogels have replaced mid water contact lens hydrogels as the soft lens material of choice. Toric lenses represented about 25 to 30% of all soft lens fits. Multifocal soft lenses are generally preferred to monovision. Daily disposable lens fits have recently increased, and in 2014, they represented 27.1% of all soft lens fits. Most lenses are prescribed on 1 to 2 weekly or monthly lens replacement regimen. Extended wear remains a minority lens wearing modality. The vast majority of those wearing reusable lenses use multipurpose lens care solutions. Lenses are mostly worn 7 d/wk. This survey has revealed prescribing trends and preferences in the United States over the past 13 years.

  7. HST Imaging of the Eye of Horus, a Double Source Plane Gravitational Lens

    Science.gov (United States)

    Wong, Kenneth

    2017-08-01

    Double source plane (DSP) gravitational lenses are extremely rare alignments of a massive lens galaxy with two background sources at distinct redshifts. The presence of two source planes provides important constraints on cosmology and galaxy structure beyond that of typical lens systems by breaking degeneracies between parameters that vary with source redshift. While these systems are extremely valuable, only a handful are known. We have discovered the first DSP lens, the Eye of Horus, in the Hyper Suprime-Cam survey and have confirmed both source redshifts with follow-up spectroscopy, making this the only known DSP lens with both source redshifts measured. Furthermore, the brightest image of the most distant source (S2) is split into a pair of images by a mass component that is undetected in our ground-based data, suggesting the presence of a satellite or line-of-sight galaxy causing this splitting. In order to better understand this system and use it for cosmology and galaxy studies, we must construct an accurate lens model, accounting for the lensing effects of both the main lens galaxy and the intermediate source. Only with deep, high-resolution imaging from HST/ACS can we accurately model this system. Our proposed multiband imaging will clearly separate out the two sources by their distinct colors, allowing us to use their extended surface brightness distributions as constraints on our lens model. These data may also reveal the satellite galaxy responsible for the splitting of the brightest image of S2. With these observations, we will be able to take full advantage of the wealth of information provided by this system.

  8. Investigation of pitch and angle in the gradual-triangle lenticular lens for point-blank LED fog lamp.

    Science.gov (United States)

    Chen, Hsi-Chao; Yang, Chi-Hao

    2014-05-10

    The effects of different pitch and angle of gradual-triangle lenticular lens for the point-blank LED fog lamp were investigated under the standard of ECE R19. The novel LED fog lamp was assembled from a point-blank LED light source, a parabolic reflector, and a gradual-triangle lenticular lens. Light tracing analysis was used for the design of the gradual-triangle lenticular lens. The pitch, which varied from 1 to 6 mm, and the apex angle, which changed from 5 to 32 deg, were both investigated in regard to the gradual-triangle lenticular lens. The optimum pitch was 5 mm, and the efficiency of the lamp system and lenticular lens could reach 93% and 98.1% by simulation, respectively. The results of experiment had over 94%, which is similar to that of simulation by normalized cross correlation (NCC) for the light intensity.

  9. Do epidermal lens cells facilitate the absorptance of diffuse light?

    Science.gov (United States)

    Brodersen, Craig R; Vogelmann, Thomas C

    2007-07-01

    Many understory plants rely on diffuse light for photosynthesis because direct light is usually scattered by upper canopy layers before it strikes the forest floor. There is a considerable gap in the literature concerning the interaction of direct and diffuse light with leaves. Some understory plants have well-developed lens-shaped epidermal cells, which have long been thought to increase the absorption of diffuse light. To assess the role of epidermal cell shape in capturing direct vs. diffuse light, we measured leaf reflectance and transmittance with an integrating sphere system using leaves with flat (Begonia erythrophylla, Citrus reticulata, and Ficus benjamina) and lens-shaped epidermal cells (B. bowerae, Colocasia esculenta, and Impatiens velvetea). In all species examined, more light was absorbed when leaves were irradiated with direct as opposed to diffuse light. When leaves were irradiated with diffuse light, more light was transmitted and more was reflected in both leaf types, resulting in absorptance values 2-3% lower than in leaves irradiated with direct light. These data suggest that lens-shaped epidermal cells do not aid the capture of diffuse light. Palisade and mesophyll cell anatomy and leaf thickness appear to have more influence in the capture and absorption of light than does epidermal cell shape.

  10. Lens barrel design of the NIRST IR Camera

    Science.gov (United States)

    Côté, Patrice; Leclerc, Mélanie; Châteauneuf, François; Marraco, Hugo

    2009-08-01

    The use of uncooled microbolometer detectors for space infrared (IR) imaging application requires high optical throughput, which leads to very fast optical design (~f/1). This directly translates into stringent requirements for components, assembly and alignment. The Institut National d'Optique (INO) in Quebec City, Canada, designed such a system for the NIRST IR Camera. The instrument is part of the Aquarius/SAC-D satellite, a cooperative mission conducted jointly by NASA and the Comisión Nacional de Actividades Espaciales (CONAE) of Argentina. Due to the tight volume and mass allocation, the NIRST camera module is an all refractive design. Since the Camera is made of two lens barrels co-registered to cover the same ground area at different wavelength bands, it also adds coregistration alignment constraints. This paper presents the optomechanical solutions and alignment scheme that enabled the successful design and flight qualification. Trade-off study between thermally induced stress and structural stiffness of the lens RTV bond is discussed. Special attention is given to lens subcell alignment integrity under random vibration encountered during launch. Detailed Finite Element Analysis (FEA) is used to check early design assumptions. Test results of the final vibration campaign are also presented.

  11. Geometric Stability and Lens Decentering in Compact Digital Cameras

    Science.gov (United States)

    Sanz-Ablanedo, Enoc; Rodríguez-Pérez, José Ramón; Armesto, Julia; Taboada, María Flor Álvarez

    2010-01-01

    A study on the geometric stability and decentering present in sensor-lens systems of six identical compact digital cameras has been conducted. With regard to geometrical stability, the variation of internal geometry parameters (principal distance, principal point position and distortion parameters) was considered. With regard to lens decentering, the amount of radial and tangential displacement resulting from decentering distortion was related with the precision of the camera and with the offset of the principal point from the geometric center of the sensor. The study was conducted with data obtained after 372 calibration processes (62 per camera). The tests were performed for each camera in three situations: during continuous use of the cameras, after camera power off/on and after the full extension and retraction of the zoom-lens. Additionally, 360 new calibrations were performed in order to study the variation of the internal geometry when the camera is rotated. The aim of this study was to relate the level of stability and decentering in a camera with the precision and quality that can be obtained. An additional goal was to provide practical recommendations about photogrammetric use of such cameras. PMID:22294886

  12. Ice-lens formation and geometrical supercooling in soils and other colloidal materials

    KAUST Repository

    Style, Robert W.

    2011-10-14

    We present a physically intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil and the geometrical supercooling of the water in the soil, a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good agreement with experiments, in particular explaining ice-lens pattern formation and surges in heave rate associated with the growth of new lenses. Importantly for systems with no frozen fringe, ice-lens formation and frost heave can be predicted given only the unfrozen properties of the soil. We use our theory to estimate ice-lens growth temperatures obtaining quantitative agreement with the limited experimental data that are currently available. Finally we suggest experiments that might be performed in order to verify this theory in more detail. The theory is generalizable to complex natural-soil scenarios and should therefore be useful in the prediction of macroscopic frost-heave rates. © 2011 American Physical Society.

  13. Pax6-dependent Shroom3 expression regulates apical constriction during lens placode invagination.

    Science.gov (United States)

    Plageman, Timothy F; Chung, Mei-I; Lou, Ming; Smith, April N; Hildebrand, Jeffrey D; Wallingford, John B; Lang, Richard A

    2010-02-01

    Embryonic development requires a complex series of relative cellular movements and shape changes that are generally referred to as morphogenesis. Although some of the mechanisms underlying morphogenesis have been identified, the process is still poorly understood. Here, we address mechanisms of epithelial morphogenesis using the vertebrate lens as a model system. We show that the apical constriction of lens epithelial cells that accompanies invagination of the lens placode is dependent on Shroom3, a molecule previously associated with apical constriction during morphogenesis of the neural plate. We show that Shroom3 is required for the apical localization of F-actin and myosin II, both crucial components of the contractile complexes required for apical constriction, and for the apical localization of Vasp, a Mena family protein with F-actin anti-capping function that is also required for morphogenesis. Finally, we show that the expression of Shroom3 is dependent on the crucial lens-induction transcription factor Pax6. This provides a previously missing link between lens-induction pathways and the morphogenesis machinery and partly explains the absence of lens morphogenesis in Pax6-deficient mutants.

  14. DotLens smartphone microscopy for biological and biomedical applications (Conference Presentation)

    Science.gov (United States)

    Sung, Yu-Lung; Zhao, Fusheng; Shih, Wei-Chuan

    2017-02-01

    Recent advances in inkjet-printed optics have created a new class of lens fabrication technique. Lenses with a tunable geometry, magnification, and focal length can be fabricated by dispensing controlled amounts of liquid polymer onto a heated surface. This fabrication technique is highly cost-effective, and can achieve optically smooth surface finish. Dubbed DotLens, a single of which weighs less than 50 mg and occupies a volume less than 50 μL. DotLens can be attached onto any smartphone camera akin to a contact lens, and enable smartphones to obtain image resolution as fine as 1 µm. The surface curvature modifies the optical path of light to the image sensor, and enables the camera to focus as close as 2 mm. This enables microscopic imaging on a smartphone without any additional attachments, and has shown great potential in mobile point-of-care diagnostic systems, particularly for histology of tissue sections and cytology of blood cells. DotLens Smartphone Microscopy represents an innovative approach fundamentally different from other smartphone microscopes. In this paper, we describe the application and performance of DotLens smartphone microscopy in biological and biomedical research. In particular, we show recent results from images collected from pathology tissue slides with cancer features. In addition, we show performance in cytological analysis of blood smear. This tool has empowered Citizen Science investigators to collect microscopic images from various interesting objects.

  15. The effects of a low-permeability lens on hyporheic exchange intensity

    Science.gov (United States)

    Su, X. R.; Shu, L. C.; Zhao, G.; Wang, M. M.; Lu, C. P.; Yao, C. C.

    2017-08-01

    Hyporheic exchange induced by dunes is a key process controlling water fluxes and biogeochemical process in river network, which has gained significant advances. Owing to the limitation of instrumental detection at small spatial scales, previous studies mainly focused on dune-induced hyporheic exchange in homogeneous systems and the impacts of a low-permeability lens on hyporheic process is still unknown. 2-D laboratory flume experiments were conducted in this study to quantitatively analyze the response mechanism of hyporheic exchange to the spatial locations of a low-permeability lens. Results indicated that the lens has hindering effects on the hyporheic exchange process and when located at the center of the horizontal location, the hindering effects were the weakest. The effect weakens when the vertical locations of the lens getting deeper. With the lens moving from the locations closer to the upstream face to that closer to the downstream face of the dunes, or moving from a shallow depth to a deep depth, the flowing path of hyporheic exchange become less influenced by the lens and the area of HZ is getting larger.

  16. Viewing Kaiser Permanente via the logistician lens.

    Science.gov (United States)

    Towill, Denis R

    2006-01-01

    The aim of this paper is to undertake a holistic comparison between NHS and Kaiser Permanente (KP) healthcare delivery systems. The paper reviews in detail the many papers and communications published on KP via the "logistics lens" which is focussed on smooth patient flow from onset of problem to completion of treatment. The paper finds that healthcare "best practice" is readily related to conventional supply chain performance metrics and engineering change model attributes. Much of the apparent success of KP is due to cultural and organisational factors. A noteworthy example deserving wide dissemination and application is in the effectiveness of interfaces between clinicians and managers. This review exposes the need for the NHS to be driven by end-to-end processing times rather than the present salami principle of separating in-patient, out-patient and other queues into neat statistics, which can be meaningless to an individual patient. Introduces clinicians and healthcare professionals to a range of tools and techniques for engineering "best practice". This method is well understood and proven in other areas of application. Particular aspects of the KP study are thus confirmatory of what is actually happening in small pockets of the NHS. The paper provides a new perspective on the performance of healthcare supply chains. New knowledge and deeper understanding of the mechanisms of success emerge from a study adopting a different viewpoint.

  17. Risk factors for contact lens-induced papillary conjunctivitis associated with silicone hydrogel contact lens wear.

    Science.gov (United States)

    Tagliaferri, Angela; Love, Thomas E; Szczotka-Flynn, Loretta B

    2014-05-01

    Contact lens-induced papillary conjunctivitis (CLPC) continues to be a major cause of dropout during extended wear of contact lenses. This retrospective study explores risk factors for the development of CLPC during extended wear of silicone hydrogel lenses. Data from 205 subjects enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens study wearing lotrafilcon A silicone hydrogel lenses for up to 30 days of continuous wear were used to determine risk factors for CLPC in this secondary analysis of the main cohort. The main covariates of interest included substantial lens-associated bacterial bioburden and topographically determined lens base curve-to-cornea fitting relationships. Additional covariates of interest included history of adverse events, time of year, race, education level, gender, and other subject demographics. Statistical analyses included univariate logistic regression to assess the impact of potential risk factors on the binary CLPC outcome and Cox proportional hazards regression to describe the impact of those factors on time-to-CLPC diagnosis. Across 12 months of follow-up, 52 subjects (25%) experienced CLPC. No associations were found between the CLPC development and the presence of bacterial bioburden, lens-to-cornea fitting relationships, history of adverse events, gender, or race. Contact lens-induced papillary conjunctivitis development followed the same seasonal trends as the local peaks in environmental allergens. Lens fit and biodeposits, in the form of lens-associated bacterial bioburden, were not associated with the development of CLPC during extended wear with lotrafilcon A silicone hydrogel lenses.

  18. Recurrence rates of herpes simplex virus keratitis in contact lens and non-contact lens wearers.

    Science.gov (United States)

    Mucci, Joti Juneja; Utz, Virginia M; Galor, Anat; Feuer, William; Jeng, Bennie H

    2009-07-01

    To evaluate the recurrence rates of herpes simplex virus (HSV) keratitis in contact lens wearers compared with non-contact lens wearers. Retrospective cohort study. Charts of patients diagnosed with HSV keratitis seen at the Cleveland Clinic between January 2001 and December 2004 were reviewed. One hundred seventeen patients were included in this study: 21 contact lens wearers and 96 non-contact lens wearers. Contact lens wearers were found to have a higher median recurrence rate (0.4 episodes/year) compared with non-contact lens wearers (0.2 episodes/year) (P=0.02). A multivariate regression evaluating factors predictive of the number of recurrences found that contact lens use remained a significant predictive variable (P=0.02) when accounting for patient demographic and disease factors and variable follow-up time. Patients with a history of HSV keratitis should be counseled about the potential increased risk of recurrence that may be associated with contact lens wear.

  19. The Sloan Lens ACS Survey. V. The full ACS strong-lens sample

    NARCIS (Netherlands)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Gavazzi, Raphael; Moustakas, Leonidas A.; Wayth, Randall; Schlegel, David J.

    2008-01-01

    We present the definitive data for the full sample of 131 strong gravitational lens candidates observed with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope by the Sloan Lens ACS (SLACS) Survey. All targets were selected for higher redshift emission lines and lower redshift

  20. Mechanical Properties of Contact Lens Materials.

    Science.gov (United States)

    Kim, Eon; Saha, Mou; Ehrmann, Klaus

    2017-11-07

    To evaluate the mechanical properties of commonly available soft contact lens materials and compare results using custom-built MicroTensometer. The Young modulus, parameters for stress relaxation, and toughness of 18 types of single vision soft contact lenses were measured using custom-built MicroTensometer. Five lenses of each type were soaked in standard phosphate buffered saline and measured at a temperature of 35°C. Each lens was flattened and sliced into a rectangular strip sample using two parallel blades. The Acuvue Moist 1-Day and SofLens Daily lenses measured lowest moduli, whereas Air Optix Night & Day Aqua and Premio measured the highest. The measured moduli for silicone hydrogel materials were generally higher compared with the hydrogels except for Dailies AquaComfort Plus. The exponential curve fitted over the decay in stress showed a consistent time constant of approximately 10 sec for most lens types measured. However, the amplitude constant varied from 2.84% for SofLens Daily to 22.39% for Acuvue TruEye 1-Day. The toughness results showed that Dailies AquaComfort Plus is strong but not necessarily tough. The mechanical properties of commonly prescribed soft contact lens materials were measured using a dedicated instrument. Its reliability was demonstrated, and modulus results were compared against published data from manufacturers and other research groups. Agreement was generally good, with only a few exceptions exceeding 15% difference. The more recently released silicone hydrogel lens types have reduced modulus, approaching that of medium or high water content hydrogel materials.

  1. Acanthamoeba keratitis and contact lens wear.

    Science.gov (United States)

    Lindsay, Richard G; Watters, Grant; Johnson, Richard; Ormonde, Susan E; Snibson, Grant R

    2007-09-01

    Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens-related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three-year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.

  2. Corneal topography and soft contact lens fit.

    Science.gov (United States)

    Young, Graeme; Schnider, Cristina; Hunt, Chris; Efron, Suzanne

    2010-05-01

    To determine which ocular topography variables affect soft contact lens fit. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.

  3. Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

    Directory of Open Access Journals (Sweden)

    Ladan Espandar

    2011-01-01

    Full Text Available Ladan Espandar1, Shameema Sikder2, Majid Moshirfar31Department of Ophthalmology, Tulane University, New Orleans, LA, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA; 3John A Moran Eye Center, University of Utah, Salt Lake City, UT, USAAbstract: Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL. The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.Keywords: hydrophilic acrylic intraocular lens, Softec HD intraocular lens, aspheric intraocular lens, IOL

  4. Lentil (Lens culinaris) lipid transfer protein Len c 3: a novel legume allergen.

    Science.gov (United States)

    Akkerdaas, J; Finkina, E I; Balandin, S V; Santos Magadán, S; Knulst, A; Fernandez-Rivas, M; Asero, R; van Ree, R; Ovchinnikova, T V

    2012-01-01

    Lentils are increasingly consumed in many parts of the world.Two allergens, Len c 1 and 2, have been reported previously. Recently, peanut and green bean lipid transfer proteins (LTPs) have been identified as the first two members of an important group of allergens that might be associated with severe food allergies. To investigate lentil LTP as a potential new allergen. Efficacy of LTP extraction was monitored at different acidic pH values, using immunoblotting with cross-reactive anti-peach LTP antiserum. Natural LTP was purified from lentil extract and expressed as recombinant allergen in Escherichia coli. Sera from 10 lentil-allergic and/or -sensitized patients (Spain: 6, Italy: 1 and the Netherlands: 3) were used to further characterize lentil LTP. Natural lentil LTP, purified from the homogenized germinated seeds and optimally extracted at pH 3, was identified and designated as allergen Len c 3. By CAP, 9/10 sera showed specific IgE to Len c 3. Recombinant (r) Len c 3 was successfully purified. The natural (n) Len c 3 CAP was completely inhibited by rLen c 3/rPru p 3. IgE binding to lentil pH 3 extract blot was completely inhibited by rLen c 3. The availability of immunochemically active nLen/rLen c 3 as a novel legume allergen facilitates further development and implementation of a third (next to peanut and green bean) legume LTP in component-resolved diagnosis strategies and contributes to evaluate the clinical importance of legume LTPs. Preferential extraction of Len c 3 (pH 3) will affect the production of sensitive extract-based diagnostic tests. Copyright © 2011 S. Karger AG, Basel.

  5. Evaluation of RGP Contact Lens Fitting in Keratoconus Patients Using Hierarchical Fuzzy Model and Genetic Algorithms.

    Science.gov (United States)

    Falahati Marvast, Fatemeh; Arabalibeik, Hossein; Alipour, Fatemeh; Sheikhtaheri, Abbas; Nouri, Leila; Soozande, Mehdi; Yarmahmoodi, Masood

    2016-01-01

    Keratoconus is a progressive non-inflammatory disease of the cornea. Rigid gas permeable contact lenses (RGPs) are prescribed when the disease progresses. Contact lens fitting and assessment is very difficult in these patients and is a concern of ophthalmologists and optometrists. In this study, a hierarchical fuzzy system is used to capture the expertise of experienced ophthalmologists during the lens evaluation phase of prescription. The system is fine-tuned using genetic algorithms. Sensitivity, specificity and accuracy of the final system are 88.9%, 94.4% and 92.6% respectively.

  6. Development of Powerhouse Using Fresnel lens

    Directory of Open Access Journals (Sweden)

    Al-Dohani Nawar Saif

    2018-01-01

    Full Text Available Solar energy is an alternative source of renewable energy. Sultanate of Oman government showed initiation on utilization of solar energy for domestic and industrial applications. Fresnel lens is one of the methods to collect maximum energy by gathering heat of the sun in the concentrated form (using solar collectors. Earlier research work discloses that Fresnel lens gave better result in terms of power output and produces lower heat loss as compared to linear –parabolic solar collectors. In this work, development of a proto Fresnel lens power house was made to generate electricity. The focused heat from Fresnel lens was used to heat the molten salt in a heat exchanger to produce the steam. The generated steam was used to rotate the steam engine coupled to a generator. In the current work, a maximum power of 30 W was produced. In addition, comparative study was carried out regarding solar salts and heat exchanger materials to understand the Fresnel powerhouse performance. Overall the present study gave valuable information regarding usage of Fresnel lens for electricity generation in Oman.

  7. TESS Lens-Bezel Assembly Modal Testing

    Science.gov (United States)

    Dilworth, Brandon J.; Karlicek, Alexandra

    2017-01-01

    The Transiting Exoplanet Survey Satellite (TESS) program, led by the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT) will be the first-ever spaceborne all-sky transit survey. MIT Lincoln Laboratory is responsible for the cameras, including the lens assemblies, detector assemblies, lens hoods, and camera mounts. TESS is scheduled to be launched in August of 2017 with the primary goal to detect small planets with bright host starts in the solar neighborhood, so that detailed characterizations of the planets and their atmospheres can be performed. The TESS payload consists of four identical cameras and a data handling unit. Each camera consists of a lens assembly with seven optical elements and a detector assembly with four charge-coupled devices (CCDs) including their associated electronics. The optical prescription requires that several of the lenses are in close proximity to a neighboring element. A finite element model (FEM) was developed to estimate the relative deflections between each lens-bezel assembly under launch loads to predict that there are adequate clearances preventing the lenses from making contact. Modal tests using non-contact response measurements were conducted to experimentally estimate the modal parameters of the lens-bezel assembly, and used to validate the initial FEM assumptions. Key Words Non-contact measurements, modal analysis, model validation

  8. Non-compliance in contact lens wear.

    Science.gov (United States)

    Claydon, B E; Efron, N

    1994-10-01

    Non-compliance is emerging as a critical issue in the contact lens field. This problem has been studied at depth in general health care situations and is seen as the responsibility of both practitioner and patient (client) working in a health care partnership. The contact lens practitioner and patient present a specific case for the study of non-compliance in areas such as hygiene, solution use, appointment attendance and wearing times. From 40 to 91% of contact lens patients have been reported as non-complaint in the use of recommended care and maintenance regimens and many of these are confused or ignorant about their behaviour. In order to arrive at a general set of conclusions from the studies published to date, it is important to understand the methodology of each study, it purpose, the definition of non-compliance used and the way the results were analysed and described. This review summarizes the research into non-compliance in the contact lens field to data. A set of general conclusions is drawn and a model for compliance in the context of contact lens practice is proposed.

  9. Spherical aberration in contact lens wear.

    Science.gov (United States)

    Lindskoog Pettersson, A; Jarkö, C; Alvin, A; Unsbo, P; Brautaset, R

    2008-08-01

    The aim of the present studies was to investigate the effect on spherical aberration of different non custom-made contact lenses, both with and without aberration control. A wavefront analyser (Zywave, Bausch & Lomb) was used to measure the aberrations in each subject's right eye uncorrected and with the different contact lenses. The first study evaluated residual spherical aberration with a standard lens (Focus Dailies Disposable, Ciba Vision) and with an aberration controlled contact lens (ACCL) (Definition AC, Optical Connection Inc.). The second study evaluated the residual spherical aberrations with a monthly disposable silicone hydrogel lens with aberration reduction (PureVision, Bausch & Lomb). Uncorrected spherical aberration was positive for all pupil sizes in both studies. In the first study, residual spherical aberration was close to zero with the standard lens for all pupil sizes whereas the ACCL over-corrected spherical aberration. The results of the second study showed that the monthly disposable lens also over-corrected the aberration making it negative. The changes in aberration were statistically significant (plenses. Since the amount of aberration varies individually we suggest that aberrations should be measured with lenses on the eye if the aim is to change spherical aberration in a certain direction.

  10. 1. History, evolution, and evolving standards of contact lens care.

    Science.gov (United States)

    Szczotka-Flynn, Loretta; Ahearn, Donald G; Barr, Joseph; Benjamin, William Joe; Kiang, Tina; Nichols, Jason J; Schein, Oliver D; Stone, Ralph P; Winterton, Lynn

    2013-01-15

    Contact lenses and lens care regimens are an important part of eyecare practices and vital to lens-wearing patients. New contact lens materials and cleaning options continue to come to market and affect how patients wear and care for their lenses. In this section we look at how the contact lens and lens solution revolution started, how it has evolved over the last 40 years, and how standards have evolved and impacted these new offerings. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  11. Molecular identification and characterisation of the glycine transporter (GLYT1) and the glutamine/glutamate transporter (ASCT2) in the rat lens

    DEFF Research Database (Denmark)

    Lim, Julie; Lorentzen, Karen Axelgaard; Kistler, Joerg

    2006-01-01

    Glutathione (GSH) is an essential antioxidant required for the maintenance of lens transparency. In the lens, GSH is maintained at unusually high concentrations as a result of direct GSH uptake and/or intracellular de novo synthesis from its precursor amino acids; cysteine, glycine and glutamine...... (EAATs) in the rat lens. In this current study, we have identified and localised additional uptake systems that contribute to GSH synthesis. Transcripts for GLYT1 (glycine transporter) and ASCT2 (glutamine/glutamate transporter) were detected in rat lens fiber cells using the reverse transcription...... fiber cells of the lens core. The molecular identification and localisation of GLYT1 and ASCT2 in the lens suggests that these transporters may be responsible for the uptake of the precursor amino acids, glycine and glutamine, which are involved in GSH synthesis. Moreover, the presence of ASCT2...

  12. New trends in intraocular lens imaging

    Science.gov (United States)

    Millán, María S.; Alba-Bueno, Francisco; Vega, Fidel

    2011-08-01

    As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a customized procedure to compensate for important sources of image degradation in the visual system of a patient, such as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand, testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea. Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena, such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle, accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the

  13. SU-E-J-69: Evaluation of the Lens Dose On the Cone Beam IGRT Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Palomo-Llinares, R; Gimeno-Olmos, J; Carmona Meseguer, V; Lliso-Valverde, F; Candela-Juan, C; Perez-Calatayud, J [Hospital La Fe, Valencia, Valencia (Spain); Pujades, M [National Dosimetry Center, Valencia, Valencia (Spain); Ballester, F [University of Valencia, Burjassot (Spain)

    2014-06-01

    Purpose: With the establishment of the IGRT as a standard technique, the extra dose that is given to the patients should be taken into account. Furthermore, it has been a recent decrease of the dose threshold in the lens, reduced to 0.5 Gy (ICRP ref 4825-3093-1464 on 21st April, 2011).The purpose of this work was to evaluate the extra dose that the lens is receive due to the Cone-Beam (CBCT) location systems in Head-and-Neck treatments. Methods: The On-Board Imaging (OBI) v 1.5 of the two Varian accelerators, one Clinac iX and one True Beam, were used to obtain the dose that this OBI version give to the lens in the Head-and-Neck location treatments. All CBCT scans were acquired with the Standard Dose Head protocol (100 kVp, 80 mA, 8 ms and 200 degree of rotation).The measurements were taken with thermoluminescence (TLD) EXTRAD (Harshaw) dosimeters placed in an anthropomorphic phantom over the eye and under 3 mm of bolus material to mimic the lens position. The center of the head was placed at the isocenter. To reduce TLD energy dependence, they were calibrated at the used beam quality. Results: The average lens dose at the lens in the OBI v 1.5 systems of the Clinac iX and the True Beam is 0.071 and 0.076 cGy/CBCT, respectively. Conclusions: The extra absorbed doses that receive the eye lenses due to one CBCT acquisition with the studied protocol is far below the new ICRP recommended threshold for the lens. However, the addition effect of several CBCT acquisition during the whole treatment should be taken into account.

  14. 3D printed helical antenna with lens

    KAUST Repository

    Farooqui, Muhammad Fahad

    2016-12-19

    The gain of an antenna can be enhanced through the integration of a lens, however this technique has traditionally been restricted to planar antennas due to fabrication limitations of standard manufacturing processes. Here, with a unique combination of 3D and 2D inkjet printing of dielectric and metallic inks respectively, we demonstrate a Fresnel lens that has been monolithically integrated to a non-planar antenna (helix) for the first time. Antenna measurements show that the integration of a Fresnel lens enhances the gain of a 2-turn helix by around 4.6 dB giving a peak gain of about 12.9 dBi at 8.8 GHz.

  15. Non-compliance with lens care and maintenance in diabetic contact lens wearers.

    Science.gov (United States)

    O'Donnell, Clare; Efron, Nathan

    2004-11-01

    We hypothesize that diabetic contact lens wearers may represent a special group displaying higher levels of compliance with their lens care regimens as a result of learned behaviour relating to maintenance of their diabetic condition. To test this hypothesis, a prospective, single centre, controlled, masked study was performed whereby 29 diabetic contact lens patients and 29 non-diabetic control subjects were issued with disposable hydrogel contact lenses and a multipurpose lens care regimen. All participants were given identical instruction on lens care and maintenance. Compliance levels were assessed at a 12-month aftercare appointment by demonstration and questionnaire. Twenty-four different aspects of compliance were scored, 12 by observation and 12 by questionnaire report, of which only two showed a significant difference between the diabetic and control groups. Although the combined population of contact lens wearers was generally compliant, there were examples of non-compliance in both groups. Neither the duration of diabetes nor the degree of metabolic control appeared to have a significant effect on compliance. The results suggest that eye care practitioners cannot assume that diabetic patients will be more compliant with contact lens care and maintenance than non-diabetic patients.

  16. Numerical Modeling of Ion Transport in an ESI-MS System

    Science.gov (United States)

    Gimelshein, Natalia; Gimelshein, Sergey; Lilly, Taylor; Moskovets, Eugene

    2014-05-01

    Gas and ion transport in the capillary-skimmer subatmospheric interface of a mass spectrometer, which is typically utilized to separate unevaporated micro-droplets from ions, was studied numerically using a two-step approach spanning multiple gas dynamic regimes. The gas flow in the heated capillary and in the interface was determined by solving numerically the Navier-Stokes equation. The capillary-to-skimmer gas/ion flow was modeled through the solution of the full Boltzmann equation with a force term. The force term, together with calculated aerodynamic drag, determined the ion motion in the gap between the capillary and skimmer. Three-dimensional modeling of the impact of the voltage applied to the Einzel lens on the transmission of doubly charged peptide ions through the skimmer orifice was compared with experimental data obtained in the companion study. Good agreement between measured and computed signals was observed. The numerical results indicate that as many as 75% of the ions that exit from the capillary are lost on the conical surface of the skimmer or capillary outer surface because of the electrostatic force and plume divergence.

  17. Effect of infrared radiation on the lens

    Directory of Open Access Journals (Sweden)

    Aly Eman

    2011-01-01

    Full Text Available Background: Infrared (IR radiation is becoming more popular in industrial manufacturing processes and in many instruments used for diagnostic and therapeutic application to the human eye. Aim : The present study was designed to investigate the effect of IR radiation on rabbit′s crystalline lens and lens membrane. Materials and Methods: Fifteen New Zealand rabbits were used in the present work. The rabbits were classified into three groups; one of them served as control. The other two groups were exposed to IR radiation for 5 or 10 minutes. Animals from these two irradiated groups were subdivided into two subgroups; one of them was decapitated directly after IR exposure, while the other subgroup was decapitated 1 hour post exposure. IR was delivered from a General Electric Lamp model 250R 50/10, placed 20 cm from the rabbit and aimed at each eye. The activity of Na + -K + ATPase was measured in the lens membrane. Soluble lens proteins were extracted and the following measurements were carried out: estimation of total soluble protein, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE and Fourier transform infrared (FTIR spectroscopy. For comparison between multiple groups, analysis of variance was used with significance level set at P < 0.001. Results: The results indicated a change in the molecular weight of different lens crystalline accompanied with changes in protein backbone structure. These changes increased for the groups exposed to IR for 10 minutes. Moreover, the activity of Na + -K + ATPase significantly decreased for all groups. Conclusions: The protein of eye lens is very sensitive to IR radiation which is hazardous and may lead to cataract.

  18. Eye lens dose in interventional cardiology.

    Science.gov (United States)

    Principi, S; Delgado Soler, C; Ginjaume, M; Beltran Vilagrasa, M; Rovira Escutia, J J; Duch, M A

    2015-07-01

    The ICRP has recently recommended reducing the occupational exposure dose limit for the lens of the eye to 20 mSv y(-1), averaged over a period of 5 y, with no year exceeding 50 mSv, instead of the current 150 mSv y(-1). This reduction will have important implications for interventional cardiology and radiology (IC/IR) personnel. In this work, lens dose received by a staff working in IC is studied in order to determine whether eye lens dose monitoring or/and additional radiological protection measures are required. Eye lens dose exposure was monitored in 10 physicians and 6 nurses. The major IC procedures performed were coronary angiography and percutaneous transluminal coronary angioplasty. The personnel were provided with two thermoluminescent dosemeters (TLDs): one calibrated in terms of Hp(3) located close to the left ear of the operator and a whole-body dosemeter calibrated in terms of Hp(10) and Hp(0.07) positioned on the lead apron. The estimated annual eye lens dose for physicians ranged between 8 and 60 mSv, for a workload of 200 procedures y(-1). Lower doses were collected for nurses, with estimated annual Hp(3) between 2 and 4 mSv y(-1). It was observed that for nurses the Hp(0.07) measurement on the lead apron is a good estimate of eye lens dose. This is not the case for physicians, where the influence of both the position and use of protective devices such as the ceiling shield is very important and produces large differences among doses both at the eyes and on the thorax. For physicians, a good correlation between Hp(3) and dose area product is shown. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Photonic crystal based polarization insensitive flat lens

    Science.gov (United States)

    Turduev, M.; Bor, E.; Kurt, H.

    2017-07-01

    The paper proposes a new design of an inhomogeneous artificially created photonic crystal lens structure consisting of annular dielectric rods to efficiently focus both transverse electric and transverse magnetic polarizations of light into the same focal point. The locations of each individual cell that contains the annular dielectric rods are determined according to a nonlinear distribution function. The inner and outer radii of the annular photonic dielectric rods are optimized with respect to the polarization insensitive frequency response of the transmission spectrum of the lens structure. The physical background of the polarization insensitive focusing mechanism is investigated in both spatial and frequency domains. Moreover, polarization independent wavefront transformation/focusing has been explored in detail by investigating the dispersion relation of the structure. Corresponding phase index distribution of the lens is attained for polarization insensitive normalized frequency range of a/λ  =  0.280 and a/λ  =  0.300, where a denotes the lattice constant of the designed structure and λ denotes the wavelength of the incident light. We show the wave transformation performance and focal point movement dynamics for both polarizations of the lens structure by specially adjusting the length of the structure. The 3D finite-difference time domain numerical analysis is also performed to verifiy that the proposed design is able to focus the wave regardless of polarization into approximately the same focal point (difference between focal distances of both polarizations stays below 0.25λ) with an operating bandwidth of 4.30% between 1476 nm and 1541 nm at telecom wavelengths. The main superiorities of the proposed lens structure are being all dielectric and compact, and having flat front and back surfaces, rendering the proposed lens design more practical in the photonic integration process in various applications such as optical switch

  20. Pulse transformer for the AA lithium lens

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    The antiprotons emanating from the target were initially focused by a magnetic horn. Later on, a Li-lens was used during operation for the SPS collider, until 1992. A Li-rod (130 mm long, 34 mm in diameter) constituted the secondary of a 1:23 pulse-transformer. The half-sine pulse rose to 1000 kA in 900 microsec. The angular acceptance was 95 mrad. In operation after 1992, for LEAR only, a more modest Li-lens was used (155 mm long, diameter 20 mm, 480 kA, risetime 240 microsec, angular acceptance 75 mrad).

  1. Herniation of the anterior lens capsule

    Directory of Open Access Journals (Sweden)

    Pereira Nolette

    2007-01-01

    Full Text Available Herniation of the anterior lens capsule is a rare abnormality in which the capsule bulges forward in the pupillary area. This herniation can be mistaken for an anterior lenticonus where both the capsule and the cortex bulge forward. The exact pathology behind this finding is still unclear. We report the clinical, ultrasound biomicroscopy (UBM and histopathological findings of a case of herniation of the anterior lens capsule. UBM helped to differentiate this entity from anterior lenticonus. Light microscopy revealed capsular splitting suggestive of capsular delamination and collection of fluid (aqueous in the area of herniation giving it a characteristic appearance.

  2. The corneal stroma during contact lens wear.

    Science.gov (United States)

    Jalbert, Isabelle; Stapleton, Fiona

    2005-03-01

    Recent technological advances have lead to novel descriptions of the microanatomy of the corneal stroma. In the first section of this review, these findings and the role they play in the maintenance of vital properties such as corneal transparency, mechanical strength, homeostasis, wound-healing response and metabolism are described. In the second part, contact lens induced stromal alterations such as acidosis, oedema, striae, thinning and opacities are reviewed as well as the more recently described phenomenon of microdot deposits and keratocyte loss with an emphasis on how lens wearing stromal effects can be minimised.

  3. Sterilization potential of contact lens solutions

    Directory of Open Access Journals (Sweden)

    Dada Vijay

    1988-01-01

    Full Text Available In a dynamic field of Contact Lens Solutions maintenance of high standards of anti-microbial activity is a must Resterilization Activity Time′ is a universally accepted yardstick for such an evaluation. In this study eight brands of indigenous popular solutions alongwith two FDA approved solutions were tested for their sterilization efficacy: Standardized suspensions of Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus fumigatus were used for the purpose. It was observed that the contact lens solutions available ir, the domestic market were not upto the mark Suggestions for improvement have also been made.

  4. IOL Implants: Lens Replacement and Cataract Surgery (Intraocular Lenses)

    Science.gov (United States)

    ... Cataract Surgery vs. Laser-Assisted Cataract Surgery Cataract Vision Simulator Cataract Pictures and Videos: What Do ... Nov. 16, 2016 An intraocular lens (or IOL) is a tiny, artificial lens for the eye. It replaces the eye's ...

  5. Immunochemical analyses of soluble lens proteins in some marine fishes

    Digital Repository Service at National Institute of Oceanography (India)

    Menezes, M.R.

    Soluble eye lens proteins of 10 fishes, belonging to the families Clupeidae, Hemirhamphidae, Lactaridae, Scombridae, Stromatidae, Psettodidae, Bothidae and Soleidae were studied by immunoelectrophoresis using the lens antiserum of Sardinella...

  6. A Simple Model of the Accommodating Lens of the Human Eye

    Science.gov (United States)

    Oommen, Vinay; Kanthakumar, Praghalathan

    2014-01-01

    The human eye is often discussed as optically equivalent to a photographic camera. The iris is compared with the shutter, the pupil to the aperture, and the retina to the film, and both have lens systems to focus rays of light. Although many similarities exist, a major difference between the two systems is the mechanism involved in focusing an…

  7. A method to reduce patient's eye lens dose in neuro-interventional radiology procedures

    Science.gov (United States)

    Safari, M. J.; Wong, J. H. D.; Kadir, K. A. A.; Sani, F. M.; Ng, K. H.

    2016-08-01

    Complex and prolonged neuro-interventional radiology procedures using the biplane angiography system increase the patient's risk of radiation-induced cataract. Physical collimation is the most effective way of reducing the radiation dose to the patient's eye lens, but in instances where collimation is not possible, an attenuator may be useful in protecting the eyes. In this study, an eye lens protector was designed and fabricated to reduce the radiation dose to the patients' eye lens during neuro-interventional procedures. The eye protector was characterised before being tested on its effectiveness in a simulated aneurysm procedure on an anthropomorphic phantom. Effects on the automatic dose rate control (ADRC) and image quality are also evaluated. The eye protector reduced the radiation dose by up to 62.1% at the eye lens. The eye protector is faintly visible in the fluoroscopy images and increased the tube current by a maximum of 3.7%. It is completely invisible in the acquisition mode and does not interfere with the clinical procedure. The eye protector placed within the radiation field of view was able to reduce the radiation dose to the eye lens by direct radiation beam of the lateral x-ray tube with minimal effect on the ADRC system.

  8. Lens design for active alignment of mobile phone cameras

    Science.gov (United States)

    Sahin, Furkan E.

    2017-06-01

    Modern mobile phones contain one or multiple high-resolution camera modules with miniature multielement lenses. Active alignment of the lens and the image sensor is a common process improvement for the integration of mobile phone camera modules to increase manufacturing yields while maintaining high resolution. Active alignment of the image sensor can offer extra degrees of freedom in lens design optimization and thereby help lens designers offer lens designs with high nominal and as-built performance.

  9. Modified matching Ronchi test to visualize lens aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hassani, Kh; Ziafi, H Hooshmand, E-mail: hassanikh@ut.ac.ir [Optics Research Lab 3, Department of Physics, University of Tehran, PO Box 14395/547, Tehran (Iran, Islamic Republic of)

    2011-09-15

    We introduce a modification to the matching Ronchi test to visualize lens aberrations with simple and inexpensive equipment available in educational optics labs. This method can help instructors and students to observe and estimate lens aberrations in real time. It is also a semi-quantitative tool for primary tests in research labs. In this work by comparing a single lens with a doublet, we can clearly demonstrate the superior quality of the doublet over the single lens, and estimate their conic constants.

  10. Correction of 157-nm lens based on phase ring aberration extraction method

    Science.gov (United States)

    Meute, Jeff; Rich, Georgia K.; Conley, Will; Smith, Bruce W.; Zavyalova, Lena V.; Cashmore, Julian S.; Ashworth, Dominic; Webb, James E.; Rich, Lisa

    2004-05-01

    Early manufacture and use of 157nm high NA lenses has presented significant challenges including: intrinsic birefringence correction, control of optical surface contamination, and the use of relatively unproven materials, coatings, and metrology. Many of these issues were addressed during the manufacture and use of International SEMATECH"s 0.85NA lens. Most significantly, we were the first to employ 157nm phase measurement interferometry (PMI) and birefringence modeling software for lens optimization. These efforts yielded significant wavefront improvement and produced one of the best wavefront-corrected 157nm lenses to date. After applying the best practices to the manufacture of the lens, we still had to overcome the difficulties of integrating the lens into the tool platform at International SEMATECH instead of at the supplier facility. After lens integration, alignment, and field optimization were complete, conventional lithography and phase ring aberration extraction techniques were used to characterize system performance. These techniques suggested a wavefront error of approximately 0.05 waves RMS--much larger than the 0.03 waves RMS predicted by 157nm PMI. In-situ wavefront correction was planned for in the early stages of this project to mitigate risks introduced by the use of development materials and techniques and field integration of the lens. In this publication, we document the development and use of a phase ring aberration extraction method for characterizing imaging performance and a technique for correcting aberrations with the addition of an optical compensation plate. Imaging results before and after the lens correction are presented and differences between actual and predicted results are discussed.

  11. Recent Outbreaks of Atypical Contact Lens-Related Keratitis: What Have We Learned?

    Science.gov (United States)

    Tu, Elmer Y.; Joslin, Charlotte E

    2010-01-01

    Purpose To examine the public health implications of two recent outbreaks of atypical contact lens-related infectious keratitis. Design A perspective based on the literature and authors’ experience. Results The contact lens-related fusarium and acanthamoeba keratitis outbreaks were both detected by dramatic rises seen in tertiary care centers in Singapore and the US, respectively. Case control studies in both outbreaks each were able to identify a strong association with the use of different contact lens disinfection solutions. Their respective recalls resulted in a steep decline of fusarium keratitis, but not of acanthamoeba keratitis. Early investigations into each solution association implicate components not directly related to their primary disinfectant, but the true pathogenesis remains unknown. However, the number of Acanthamoeba cases individually attributed to each of almost all available disinfection systems exceeds previously understood total US incidence, suggesting other risk factors. Current standards do not require demonstration of anti-acanthamoebal activity. Yet, despite the inclusion of fusarium in mandatory testing for solutions, current pre-market testing was not predictive of the outbreak. Conclusions The two recent outbreaks of atypical contact-lens related keratitis have reinforced the value of tertiary care eye care centers in detecting early rises in rare infections and the power of adaptable, well-designed epidemiologic investigations. While fusarium keratitis has significantly declined with the recall of Renu with Moistureloc, the persistence of Acanthamoeba keratitis begs fundamental changes in contact lens hygiene practices, inclusion of acanthamoeba as a test organism and contact lens disinfectant test regimens for all contact lens–related pathogens which are verifiably reflective of end user contact lens wear complications. PMID:21036209

  12. 21 CFR 886.5420 - Contact lens inserter/remover.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Contact lens inserter/remover. 886.5420 Section 886.5420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5420 Contact lens inserter/remover. (a) Identification. A contact lens inserter...

  13. 21 CFR 886.1405 - Ophthalmic trial lens set.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic trial lens set. 886.1405 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1405 Ophthalmic trial lens set. (a) Identification. An ophthalmic trial lens set is a device that is a set of lenses of various dioptric powers...

  14. 21 CFR 886.1410 - Ophthalmic trial lens clip.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic trial lens clip. 886.1410 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1410 Ophthalmic trial lens clip. (a) Identification. An ophthalmic trial lens clip is a device intended to hold prisms, spheres, cylinders, or...

  15. Lens design for the infrared

    Science.gov (United States)

    Fischer, Robert E.

    1991-10-01

    Thermal, or infrared imaging systems have continued to increase in importance over the years. This is due to several factors: The applications of IR systems have grown dynamically in importance both in the military as well as in industrial applications IR detector technology has matured substantially, to the point where many IR detectors are available and economically producible This increased importance of infrared systems, combined with continually better performing and more cost effective IR detectors has put an ever increasing demand on the optical system and it's design. Although many of the classical optical design and engineering related derivations, guidelines, tradeoffs, and other considerations developed for visible systems can be applied directly to infrared systems, there are many important considerations, some of them quite subtle, that are considerably different in the infrared, and which can cause devastating problems if not properly taken into account. In fact, if one were to design the optics for an infrared scanning system using totally the guidelines derived from visible system engineering principles, there is a good chance that the system would perform poorly, if at all. In this paper we will review the many aspects of optical system design for the infrared. Although we intend to cover primarily those areas which are unique to IR systems, one will quickly realize that this will in reality cause us to cover most aspects of optical design technology.

  16. Injectable Intraocular lens materials based upon hydrogels

    NARCIS (Netherlands)

    de Groot, JH; van Beijma, FJ; Haitjema, HJ; Dillingham, KA; Hodd, KA; Koopmans, SA; Norrby, S

    2001-01-01

    The possibilities to develop an injectable hydrogel lens were investigated. Aqueous solutions of reactive polymers in combination with a water-soluble blue light photoinitiator were transformed into hydrogels by irradiation with blue light. Poly(ethylene glycol) diacrylates (PEGDA) with low

  17. Ocular Lens Implantation In Benin City, Nigeria

    African Journals Online (AJOL)

    Intra ocular lens implantation is a relatively new surgical procedure in developing countries, although it has been the norm in developed countries for over three decades. It is carried out during cataract surgery for the purpose of aphakic correction. The aim of the study was to assess the level of awareness of the general ...

  18. Corneal ring infiltration in contact lens wearers

    Directory of Open Access Journals (Sweden)

    Seyed Ali Tabatabaei

    2017-01-01

    Full Text Available To report a case of atypical sterile ring infiltrates during wearing soft silicone hydrogel contact lens due to poor lens care. A 29-year-old woman presented with complaints of pain, redness, and morning discharge. She was wearing soft silicone hydrogel contact lens previously; her current symptoms began 1 week before presentation. On examination, best-corrected visual acuity was 20/40 in that eye. Slit-lamp examination revealed dense, ring-shaped infiltrate involving both the superficial and deep stromal layers with lucid interval to the limbus, edema of the epithelium, epithelial defect, and vascularization of the superior limbus. Cornea-specific in vivo laser confocal microscopy (Heidelberg Retina Tomograph 2 Rostock Cornea Module, HRT 2-RCM, Heidelberg Engineering GmbH, Dossenheim, Germany revealed Langerhans cells and no sign of Acanthamoeba or fungal features, using lid scraping and anti-inflammatory drops; her vision completely recovered. We reported an atypical case of a sterile corneal ring infiltrate associated with soft contact lens wearing; smear, culture, and confocal microscopy confirmed a sterile inflammatory reaction.

  19. Corneal ring infiltration in contact lens wearers.

    Science.gov (United States)

    Tabatabaei, Seyed Ali; Soleimani, Mohammad; Johari, Mohammadkarim

    2017-01-01

    To report a case of atypical sterile ring infiltrates during wearing soft silicone hydrogel contact lens due to poor lens care. A 29-year-old woman presented with complaints of pain, redness, and morning discharge. She was wearing soft silicone hydrogel contact lens previously; her current symptoms began 1 week before presentation. On examination, best-corrected visual acuity was 20/40 in that eye. Slit-lamp examination revealed dense, ring-shaped infiltrate involving both the superficial and deep stromal layers with lucid interval to the limbus, edema of the epithelium, epithelial defect, and vascularization of the superior limbus. Cornea-specific in vivo laser confocal microscopy (Heidelberg Retina Tomograph 2 Rostock Cornea Module, HRT 2-RCM, Heidelberg Engineering GmbH, Dossenheim, Germany) revealed Langerhans cells and no sign of Acanthamoeba or fungal features, using lid scraping and anti-inflammatory drops; her vision completely recovered. We reported an atypical case of a sterile corneal ring infiltrate associated with soft contact lens wearing; smear, culture, and confocal microscopy confirmed a sterile inflammatory reaction.

  20. High Accuracy Dual Lens Transmittance Measurements

    Science.gov (United States)

    2007-08-01

    measurement of lens transmission,” Metrologia 37, 603–605 (2000). 3. B. Munro, “Quantum information processing with light and its requirement for detectors...5. N. P. Fox, “Trap detectors and their properties,” Metrologia 28, 197–202 (1991). 5402 APPLIED OPTICS Vol. 46, No. 22 1 August 2007 6. S. L

  1. Stability for the Lens Rigidity Problem

    Science.gov (United States)

    Bao, Gang; Zhang, Hai

    2017-09-01

    Let g be a Riemannian metric for R^d ({d ≥q 3}) which differs from the Euclidean metric only in a smooth and strictly convex bounded domain M. The lens rigidity problem is concerned with recovering the metric g inside M from the corresponding lens relation on the boundary {partial M}. In this paper, the stability of the lens rigidity problem is investigated for metrics which are a priori close to a given non-trapping metric satisfying the "strong fold-regular" condition. A metric g is called strong fold-regular if for each point {x\\in M}, there exists a set of geodesics passing through x whose conormal bundle covers {T^*xM}. Moreover, these geodesics contain either no conjugate points or only fold conjugate points with a non-degeneracy condition. Examples of strong fold-regular metrics are constructed. Our main result gives the first stability result for the lens rigidity problem in the case of anisotropic metrics which allow conjugate points. The approach is based on the study of the linearized inverse problem of recovering a metric from its induced geodesic flow, which is a weighted geodesic X-ray transform problem for symmetric 2-tensor fields. A key ingredient is to show that the kernel of the X-ray transform on symmetric solenoidal 2-tensor fields is of finite dimension. It remains open whether the kernel space is trivial or not.

  2. Scientific performance assessments through a gender lens

    DEFF Research Database (Denmark)

    Nielsen, Mathias Wullum

    2017-01-01

    The focus on excellence and quality assurance in the academy has spawned a signifi cant increase in the use of bibliometric measures in performance assessments of individual researchers. This article investigates the organizational consequences of this development through a gender lens. Based...

  3. Extreme-angle broadband metamaterial lens.

    Science.gov (United States)

    Kundtz, Nathan; Smith, David R

    2010-02-01

    For centuries, the conventional approach to lens design has been to grind the surfaces of a uniform material in such a manner as to sculpt the paths that rays of light follow as they transit through the interfaces. Refractive lenses formed by this procedure of bending the surfaces can be of extremely high quality, but are nevertheless limited by geometrical and wave aberrations that are inherent to the manner in which light refracts at the interface between two materials. Conceptually, a more natural--but usually less convenient--approach to lens design would be to vary the refractive index throughout an entire volume of space. In this manner, far greater control can be achieved over the ray trajectories. Here, we demonstrate how powerful emerging techniques in the field of transformation optics can be used to harness the flexibility of gradient index materials for imaging applications. In particular we design and experimentally demonstrate a lens that is broadband (more than a full decade bandwidth), has a field-of-view approaching 180 degrees and zero f-number. Measurements on a metamaterial implementation of the lens illustrate the practicality of transformation optics to achieve a new class of optical devices.

  4. Extracapsular cataract extraction with intraocular lens implantation ...

    African Journals Online (AJOL)

    Cataract is the leading cause of blindness in leprosy patients. Sight restoration to blind leprosy patients prevents them from injuring their anaesthetic limbs. The visual outcome and complications of extracapsular cataract extraction with intraocular lens implant in 42 leprosy and 91 non-leprosy patients were compared.

  5. Minus Piggyback Lens Overlaying ReSTOR® Multifocal Lens in High Myopia

    Directory of Open Access Journals (Sweden)

    Isha Gupta

    2013-06-01

    Full Text Available Background: We report the case of a 40-year-old female patient treated with implantation of the Acrysof® IQ ReSTOR® lens (Alcon, Fort Worth, Tex., USA with overlaying Acrysof EXpand® minus piggyback lens (Alcon. Methods: The patient had high myopia and was diagnosed with presbyopia and bilateral posterior subcapsular cataract. She desired to be spectacle-free and opted to undergo bilateral placement of the ReSTOR multifocal lens. The necessary intraocular lens (IOL power was +3.5 in the right eye and +4.0 in the left eye, though the range of commercially available ReSTOR lenses is +6.0 to +34.0 D. In order to achieve emmetropia in this case of high myopia, it was determined that an EXpand minus piggyback lens would be necessary. Results: Implantation of the ReSTOR lens with overlaying EXpand minus piggyback lens was performed successfully and without complication. At 5 months postoperatively, the patient had 20/20 uncorrected visual acuity in both eyes. She reported a high level of satisfaction and was able to return to her daily activities including reading and driving without spectacles. Conclusion: We report successful primary implantation of AcrySof EXpand minus piggyback lenses overlying the AcrySof IQ ReSTOR lens in a patient with high myopia. Long-term follow-up and further evaluation is necessary to establish piggyback IOL implantation with multifocal IOL as an accepted treatment for high myopia with presbyopia.

  6. A Complex Lens for a Complex Eye.

    Science.gov (United States)

    Stahl, Aaron L; Baucom, Regina S; Cook, Tiffany A; Buschbeck, Elke K

    2017-09-02

    A key innovation for high resolution eyes is a sophisticated lens that precisely focuses light onto photoreceptors. The eyes of holometabolous larvae range from very simple eyes that merely detect light to eyes that are capable of high spatial resolution. Particularly interesting are the bifocal lenses of Thermonectus marmoratus larvae, which differentially focus light on spectrally-distinct retinas. While functional aspects of insect lenses have been relatively well studied, little work has explored their molecular makeup, especially in regard to more complex eye types. To investigate this question, we took a transcriptomic and proteomic approach to identify the major proteins contributing to the principal bifocal lenses of T. marmoratus larvae. Mass spectrometry revealed 10 major lens proteins. Six of these share sequence homology with cuticular proteins, a large class of proteins that are also major components of corneal lenses from adult compound eyes of Drosophila melanogaster and Anopheles gambiae. Two proteins were identified as house-keeping genes and the final two lack any sequence homologies to known genes. Overall the composition seems to follow a pattern of co-opting transparent and optically dense proteins, similar to what has been described for other animal lenses. To identify cells responsible for the secretion of specific lens proteins, we performed in situ hybridization studies and found some expression differences between distal and proximal corneagenous cells. Since the distal cells likely give rise to the periphery and the proximal cells to the center of the lens, our findings highlight a possible mechanism for establishing structural differences that are in line with the bifocal nature of these lenses. A better understanding of lens composition provides insights into the evolution of proper focusing, which is an important step in the transition between low-resolution and high-resolution eyes. © The Author 2017. Published by Oxford University

  7. Incidence of rhegmatogenous retinal detachment after bag-in-the-lens intraocular lens implantation.

    Science.gov (United States)

    Tassignon, Marie-José; Van den Heurck, Jonas J I; Boven, Kim B M; Van Looveren, Jan; Wouters, Kristien; Bali, Ernesto; Ní Dhubhghaill, Sorcha; Mathysen, Danny G P

    2015-11-01

    To determine the incidence of rhegmatogenous retinal detachment (RRD) and associated risk factors after phacoemulsification and bag-in-the-lens intraocular lens (IOL) implantation. Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. Prospective cohort study. All consecutive bag-in-the-lens IOL implantations performed between January 2001 and December 2007 were included, with the exception of combined procedures and IOL exchanges. The retinal detachment (RD) incidence was studied in the total cohort, in a subgroup of patients with 1 to 5 years of follow-up, and finally in the group remaining after exclusion of all risk factors except gender. RD after bag-in-the-lens IOL implantation in 1323 eyes with an average follow-up of 44.75 months (range 0 to 152 months) was found in 19 eyes (1.44%). The 1-year RD incidence was 0.49% (5 RD cases in 1024 eyes) (0.00% in patients without risk factors). The 2-year cumulative RD incidence was 0.84% (9 RD cases in 931 eyes; 0.15% without risk factors). Four clinically significant risk factors were confirmed: male gender, young age at time of surgery (intellectual property rights to the bag-in-the-lens intraocular lens (U.S. patent 6 027 531; EU patent 009406794; PCT/120268), which is licensed to Morcher GmbH, Stuttgart, Germany. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  8. Intrinsic lens potential of neural retina inhibited by Notch signaling as the cause of lens transdifferentiation.

    Science.gov (United States)

    Iida, Hideaki; Ishii, Yasuo; Kondoh, Hisato

    2017-01-15

    Embryonic neural retinas of avians produce lenses under spreading culture conditions. This phenomenon has been regarded as a paradigm of transdifferentiation due to the overt change in cell type. Here we elucidated the underlying mechanisms. Retina-to-lens transdifferentiation occurs in spreading cultures, suggesting that it is triggered by altered cell-cell interactions. Thus, we tested the involvement of Notch signaling based on its role in retinal neurogenesis. Starting from E8 retina, a small number of crystallin-expressing lens cells began to develop after 20 days in control spreading cultures. By contrast, addition of Notch signal inhibitors to cultures after day 2 strongly promoted lens development beginning at day 11, and a 10-fold increase in δ-crystallin expression level. After Notch signal inhibition, transcription factor genes that regulate the early stage of eye development, Prox1 and Pitx3, were sequentially activated. These observations indicate that the lens differentiation potential is intrinsic to the neural retina, and this potential is repressed by Notch signaling during normal embryogenesis. Therefore, Notch suppression leads to lens transdifferentiation by disinhibiting the neural retina-intrinsic program of lens development. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Modelling and integration of a time-resolved ion beam measurement system for laser ionized beams at ISOLDE

    CERN Document Server

    Ringvall-Moberg, Annie Julia

    2015-01-01

    The purpose of this project was to simulate designs to determine the optimal ion optic configuration for the detection of secondary electrons using a MagneTOF detector. The secondary electrons are emitted from a target plate, made out of aluminum, when an ion beam hits the target plate. The electrons are then emitted according to a cosine distribution. The intention is to detect these electrons with a MagneTOF detector. Since the target plate and the detector were already mounted in a chamber the main tasks were to accelerate and focus the emitted electrons into the entrance of the detector. This was done by using an electrical grid and an Einzel lens. An already existing setup, created in Autodesk Inventor Professional, was used and modified. The setup was then imported into SIMION were the emission of electrons could be simulated. The desired percentage of detected electrons, i.e. the electrons which enter the MagneTOF detector with an energy greater than 1 keV, is in this case 10% or more. This was obtai...

  10. Upgrade of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN.

    Science.gov (United States)

    Toivanen, V; Bellodi, G; Dimov, V; Küchler, D; Lombardi, A M; Maintrot, M

    2016-02-01

    Linac3 is the first accelerator in the heavy ion injector chain of the Large Hadron Collider (LHC), providing multiply charged heavy ion beams for the CERN experimental program. The ion beams are produced with GTS-LHC, a 14.5 GHz electron cyclotron resonance ion source, operated in afterglow mode. Improvement of the GTS-LHC beam formation and beam transport along Linac3 is part of the upgrade program of the injector chain in preparation for the future high luminosity LHC. A mismatch between the ion beam properties in the ion source extraction region and the acceptance of the following Low Energy Beam Transport (LEBT) section has been identified as one of the factors limiting the Linac3 performance. The installation of a new focusing element, an einzel lens, into the GTS-LHC extraction region is foreseen as a part of the Linac3 upgrade, as well as a redesign of the first section of the LEBT. Details of the upgrade and results of a beam dynamics study of the extraction region and LEBT modifications will be presented.

  11. Synchronous imaging of the pulse response of the ciliary muscle and lens with SD-OCT (Conference Presentation)

    Science.gov (United States)

    Chang, Yu-Cherng; Pham, Alex; Williams, Siobhan; Alawa, Karam A.; de Freitas, Carolina; Ruggeri, Marco; Parel, Jean-Marie A.; Manns, Fabrice

    2017-02-01

    Purpose: To determine the dynamic interaction between ciliary muscle and lens during accommodation and disaccommodation through synchronous imaging of ciliary muscle and lens response to pulse stimulus Methods: The ciliary muscle and lens were imaged simultaneously in a 33 year old subject responding to a 4D pulse stimulus (accommodative stimulus at 1.7 s, disaccommodative stimulus at 7.7 s) using an existing imaging system (Ruggeri et al, 2016) consisting of an Anterior Segment Optical Coherence Tomography system, Ciliary Muscle Optical Coherence Tomography system, and custom-built accommodation module. OCT images were recorded at an effective frame rate of 13.0 frames per second for a total scan time of 11.5 s. An automated segmentation algorithm was applied to images of the anterior segment to detect the boundaries of the cornea and lens, from which lens thickness was extracted. Segmentation of the ciliary muscle was performed manually and then corrected for distortion due to refraction of the beam to obtain measurements of thicknesses at the apex and fixed distances from the scleral spur. Results: The dynamic biometric response to a pulse stimulus at 4D was determined for both the ciliary muscle and lens, suggesting the ciliary muscle and lens interact differently in accommodation and disaccommodation. Conclusions: The study introduces new data and analyses of the ciliary muscle and lens interaction during a complete accommodative response from the relaxed to the accommodated state and back, providing insight into the interplay between individual elements in the accommodative system and how their relationships may change with age.

  12. Non-invasive objective and contemporary methods for measuring ocular surface inflammation in soft contact lens wearers - A review.

    Science.gov (United States)

    Chao, Cecilia; Richdale, Kathryn; Jalbert, Isabelle; Doung, Kim; Gokhale, Moneisha

    2017-10-01

    Contact lens wear is one of the primary risk factors for the development of ocular surface inflammatory events. The purpose of this review is to examine and summarize existing knowledge on the mechanisms of contact lens related ocular surface inflammation and the evidence for the effectiveness of current objective methods to measure ocular surface inflammation. Contact lens wear is postulated to trigger an inflammatory response on the ocular surface due to mechanical, chemical, hypoxic stress, or by the introduction of microbes and their toxins. Apart from the traditional signs of inflammation, such as swelling, oedema, redness and heat, on the ocular surface, other methods to measure ocular surface inflammation in sub-clinical levels include tear inflammatory mediator concentrations, conjunctival cell morphology, and corneal epithelial dendritic cell density and morphology. Tear inflammatory mediator concentrations are up- or down-regulated during contact lens wear, with or without the presence of associated inflammatory events. There is higher conjunctival cell metaplasia observed with contact lens wear, but changes in goblet cell density are inconclusive. Dendritic cell density is seen to increase soon after initiating soft contact lens wear. The long term effects of contact lens wear on dendritic cell migration in the cornea and conjunctiva, including the lid wiper area, require further investigation. Currently patient factors, such as age, smoking, systemic diseases and genetic profile are being studied. A better understanding of these mechanisms may facilitate the development of new management options and strategies to minimize ocular surface inflammation related to contact lens wear. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  13. Optical Tests on a Curve Fresnel Lens as Secondary Optics for Solar Troughs

    Directory of Open Access Journals (Sweden)

    D. Fontani

    2017-01-01

    Full Text Available A curve Fresnel lens is developed as secondary concentrator for solar parabolic troughs to reduce the number of photovoltaic cells. Specific measurements and optical tests are used to evaluate the optical features of manufactured samples. The cylindrical Fresnel lens transforms the focal line, produced by the primary mirror, into a series of focal points. The execution of special laboratory tests on some secondary concentrator samples is discussed in detail, illustrating the methodologies tailored to the specific case. Focusing tests are performed, illuminating different areas of the lens with solar divergence light and acquiring images on the plane of the photocell using a CMOS camera. Concentration measurements are carried out to select the best performing samples of curve Fresnel lens. The insertion of the secondary optics within the concentrating photovoltaic (CPV trough doubles the solar concentration of the system. The mean concentration ratio is 1.73, 2.13, and 2.09 for the three tested lenses. The concentration ratio of the solar trough is 140 and approaches 300 after the introduction of the secondary lens.

  14. Rho signaling pathway and apical constriction in the early lens placode.

    Science.gov (United States)

    Borges, Ricardo Moraes; Lamers, Marcelo Lazzaron; Forti, Fabio Luis; Santos, Marinilce Fagundes Dos; Yan, Chao Yun Irene

    2011-05-01

    Epithelial invagination in many model systems is driven by apical cell constriction, mediated by actin and myosin II contraction regulated by GTPase activity. Here we investigate apical constriction during chick lens placode invagination. Inhibition of actin polymerization and myosin II activity by cytochalasin D or blebbistatin prevents lens invagination. To further verify if lens placode invaginate through apical constriction, we analyzed the role of Rho-ROCK pathway. Rho GTPases expression at the apical portion of the lens placode occurs with the same dynamics as that of the cytoskeleton. Overexpression of the pan-Rho inhibitor C3 exotoxin abolished invagination and had a strong effect on apical myosin II enrichment and a mild effect on apical actin localization. In contrast, pharmacological inhibition of ROCK activity interfered significantly with apical enrichment of both actin and myosin. These results suggest that apical constriction in lens invagination involves ROCK but apical concentration of actin and myosin are regulated through different pathways upstream of ROCK. genesis 49:368-379, 2011. 2011 Wiley-Liss, Inc.

  15. Radiation exposure to the eye lens of orthopaedic surgeons during various orthopaedic procedures.

    Science.gov (United States)

    Romanova, K; Vassileva, J; Alyakov, M

    2015-07-01

    The aim of the present study was to assess the radiation dose to the eye lens of orthopaedic surgeons during various orthopaedic procedures and to make efforts to ensure that radiation protection is optimised. The study was performed for Fractura femoris and Fractura cruris procedures performed in orthopaedic operating theatres, as well as for fractures of wrist, ankle and hand/shoulder performed in the emergency trauma room. The highest mean value of the eye lens dose of 47.2 μSv and higher mean fluoroscopy time of 3 min, as well as the corresponding highest maximum values of 77.1 μSv and 5.0 min were observed for the Fractura femoris procedure performed with the Biplanar 500e fluoroscopy systems. At a normal workload, the estimated mean annual dose values do not exceed the annual occupational dose limit for the lens of eye, but at a heavy workload in the department, this dose limit could be achieved or exceeded. The use of protective lead glasses is recommended as they could reduce the radiation exposure of the lens of the eye. The phantom measurements demonstrated that the use of half-dose mode could additionally reduce dose to the operator's eye lens. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Metamaterial magnetoinductive lens performance as a function of field strength.

    Science.gov (United States)

    Algarín, José M; Freire, Manuel J; Breuer, Felix; Behr, Volker C

    2014-10-01

    Metamaterials are artificial composites that exhibit exotic electromagnetic properties, as the ability of metamaterial slabs to behave like lenses with sub-wavelength resolution for the electric or the magnetic field. In previous works, the authors investigated magnetic resonance imaging (MRI) applications of metamaterial slabs that behave like lenses for the radiofrequency magnetic field. In particular, the authors investigated the ability of MRI metamaterial lenses to increase the signal-to-noise ratio (SNR) of surface coils, and to localize the field of view (FOV) of the coils, which is of interest for parallel MRI (pMRI) applications. A metamaterial lens placed between a surface coil and the tissue enhances the sensitivity of the coil. Although the metamaterial lens introduces losses which add to the losses of the tissue, the enhancement of the sensitivity can compensate these additional losses and the SNR of the coil is increased. In a previous work, an optimization procedure was followed to find a metamaterial structure with minimum losses that will maximize the SNR. This structure was termed magnetoinductive (MI) lens by the authors. The properties of surface coils in the presence of MI lenses were investigated in previous works at the proton frequency of 1.5 T systems. The different frequency dependence of the losses in both the MI lenses and the tissue encouraged us to investigate the performance of MI lenses at different frequencies. Thus, in the present work, the SNR and the pMRI ability of MI lenses are investigated as a function of field strength. A numerical analysis is carried out with an algorithm developed by the authors to predict the SNR behavior of a surface coil loaded with a MI lens at the proton frequencies of 0.5 T, 1.5 T and 3 T systems. The results show that, at 0.5 T, there is a gain in the SNR for short distances, but the SNR is highly degraded at deeper distances. However, at 1.5 T and 3T, the MI lenses provide a gain in the SNR up to a

  17. Nanosecond KTN varifocal lens without electric field induced phase transition

    Science.gov (United States)

    Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Yin, Stuart (Shizhuo); Hoffman, Robert C.

    2017-08-01

    This paper presents a nanosecond speed KTN varifocal lens. The tuning principle of varifocal lens is based on the high-speed refractive index modulation from the nanosecond speed tunable electric field. A response time on the order of nanoseconds was experimentally demonstrated, which is the fastest varifocal lens reported so far. The results confirmed that the tuning speed of the KTN varifocal lens could be significantly increased by avoiding the electric field induced phase transition. Such a nanosecond speed varifocal lens can be greatly beneficial for a variety of applications that demand high speed axial scanning, such as high-resolution 3D imaging and high-speed 3D printing.

  18. Acid phosphatase and lipid peroxidation in human cataractous lens epithelium

    Directory of Open Access Journals (Sweden)

    Vasavada Abhay

    1993-01-01

    Full Text Available The anterior lens epithelial cells undergo a variety of degenerative and proliferative changes during cataract formation. Acid phosphatase is primarily responsible for tissue regeneration and tissue repair. The lipid hydroperoxides that are obtained by lipid peroxidation of polysaturated or unsaturated fatty acids bring about deterioration of biological membranes at cellular and tissue levels. Acid phosphatase and lipid peroxidation activities were studied on the lens epithelial cells of nuclear cataract, posterior subcapsular cataract, mature cataract, and mixed cataract. Of these, mature cataractous lens epithelium showed maximum activity for acid phosphatase (516.83 moles of p-nitrophenol released/g lens epithelium and maximum levels of lipid peroxidation (86.29 O.D./min/g lens epithelium. In contrast, mixed cataractous lens epithelium showed minimum activity of acid phosphatase (222.61 moles of p-nitrophenol released/g lens epithelium and minimum levels of lipid peroxidation (54.23 O.D./min/g lens epithelium. From our study, we correlated the maximum activity of acid phosphatase in mature cataractous lens epithelium with the increased areas of superimposed cells associated with the formation of mature cataract. Likewise, the maximum levels of lipid peroxidation in mature cataractous lens epithelium was correlated with increased permeability of the plasma membrane. Conversely, the minimum levels of lipid peroxidation in mixed cataractous lens epithelium makes us presume that factors other than lipid peroxidation may also account for the formation of mixed type of cataract.

  19. Patient compliance during contact lens wear: perceptions, awareness, and behavior.

    Science.gov (United States)

    Bui, Thai H; Cavanagh, H Dwight; Robertson, Danielle M

    2010-11-01

    Patient noncompliance with recommended hygienic practices in contact lens wear is often considered a significant risk factor for microbial keratitis and adverse contact lens-related events. Despite advancements in lens materials and care solutions, noncompliant behavior continues to hinder efforts to maximize contact lens safety. The objective of this pilot study was to assess the relationship between perceived and actual compliance with awareness of risk and behavior. One hundred sixty-two established contact lens wearers were sequentially evaluated after their routine contact lens examination at the Optometry Clinic at the University of Texas Southwestern Medical Center at Dallas, TX. Each patient was questioned by a single trained interviewer regarding his or her lens care practices and knowledge of risk factors associated with lens wear. Eighty-six percent of patients believed they were compliant with lens wear and care practices; 14% identified themselves as noncompliant. Using a scoring model, 32% demonstrated good compliance, 44% exhibited average compliance, and 24% were noncompliant; age was a significant factor (P = 0.020). Only 34% of patients who perceived themselves as compliant exhibited a good level of compliance (Plens case was the only behavior associated with a positive history for having experienced a prior contact lens-related complication (P = 0.002). Perceived compliance is not an indicator for appropriate patient behavior. A large proportion of patients remain noncompliant despite awareness of risk. Education alone is not a sufficient strategy to improve behavior; newer approaches aimed at improving compliance with lens care practices are urgently needed.

  20. Effects of a tryptophan supplemented diet and U.V. radiation on the rat lens.

    Science.gov (United States)

    Mathur, R L; Sahai, P

    1990-01-01

    Rats maintained on a tryptophan supplemented diet and exposed to U.V. radiation showed decreased concentration of ascorbic acid in serum. In the lens, a small increase in the urea-mercaptoethanol soluble fraction was observed suggesting some oxidation of P-SH groups. The decreased concentrations of lens glutathione and ascorbic acid were accompanied with increased concentration of malondialdehyde suggesting increased oxidative stress. The activities of glutathione peroxidase decreased by about 40%. Though the activity of glutathione reductase decreased by about 58%, addition of FAD in the enzyme assay system showed restoration of lost activity. Additive effect of raised serum tryptophan concentration and ultraviolet radiation in causing damage to the eye lens is suggested.

  1. Electron Lens Construction for the Integrable Optics Test Accelerator at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, Mike [Fermilab; Carlson, Kermit [Fermilab; Nobrega, Lucy [Fermilab; Stancari, Giulio [Fermilab; Valishev, Alexander [Fermilab

    2016-06-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. Construction of an electron lens for IOTA is necessary for both electron and proton operation. Components required for the Electron Lens design include; a 0.8 T conventional water-cooled main solenoid, and magnetic bending and focusing elements. The foundation of the design relies on repurposing the Fermilab Tevatron Electron Lens II (TELII) gun and collector under ultra-high vacuum (UHV) conditions.

  2. Compositional Dependence Of Hardness Of Ge-Sb-Se Glass For Molded Lens Applications

    Directory of Open Access Journals (Sweden)

    Park J.K.

    2015-06-01

    Full Text Available Chalcogenide glass in the ternary Ge-Sb-Se system is inherently moldable, thus being considered as a strong candidate material for use in infrared-transmitting lens applications from the viewpoint of thermal and mechanical stability. In an effort to experimentally determine compositional region suitable for the molded lens applications, we evaluate its compositional dependence of hardness. Among the constituent atoms, Ge content turns out to exert a most conspicuous correlation with hardness. This phenomenological behavior is then explained in connection with the structural evolution that Ge brings about.

  3. Acanthamoeba Species Keratitis in a Soft Contact Lens Wearer Molecularly Linked to Well Water

    Directory of Open Access Journals (Sweden)

    Samira Mubareka

    2006-01-01

    Full Text Available Acanthamoeba species keratitis has been associated with soft contact lens wear. In the present report, an epidemiological link was established between the patient's isolate and well water from the home using molecular methods. To the authors' knowledge, this is the first case in Canada where such a link has been established. Primary care practitioners and specialists, including ophthalmologists and infectious diseases specialists, must maintain a high degree of clinical suspicion in soft contact lens wearers with keratitis unresponsive to conventional topical and systemic treatment.

  4. Developments of wide field submillimeter optics and lens antenna-coupled MKID cameras

    Science.gov (United States)

    Sekimoto, Y.; Nitta, T.; Karatsu, K.; Sekine, M.; Sekiguchi, S.; Okada, T.; Shu, S.; Noguchi, T.; Naruse, M.; Mitsui, K.; Okada, N.; Tsuzuki, T.; Dominjon, A.; Matsuo, H.

    2014-07-01

    Wide field cryogenic optics and millimeter-wave Microwave Kinetic Inductance Detector (MKID) cameras with Si lens array have been developed. MKID is a Cooper-pair breaking photon detector and consists of supercon- ducting resonators which enable microwave (~GHz) frequency multiplexing. Antenna-coupled Aluminum CPW resonators are put in a line on a Si substrate to be read by a pair of coaxial cables. A 220 GHz - 600 pixels MKID camera with anti-reflection (AR) coated Si lens has been demonstrated in an 0.1 K cryostat. A compact cryogenic system with high refractive index materials has been developed for the MKID camera.

  5. Improvement of disturbing color effects depending on the axial color of an automotive headlamp lens.

    Science.gov (United States)

    Lee, Hyun Soo; Park, Hyun Jung; Kwak, Joon Seop

    2017-06-10

    Light-emitting diodes (LEDs) are causing big changes in the automotive lighting field. Optical systems with LEDs can use a plastic lens, which means almost all shapes can be made through plastic injection molding. Already, some car manufacturers are adopting this technology in their designs to express their own identities to customers. However, to use this technology, an important defect has to be overcome, which is color aberration near the cutoff line of the low-beam. In this paper, the criteria for measuring the color coordinates are established and simulations for axial color aberration in the plastic lens are carried out.

  6. Wind lens technology and its application to wind and water turbine and beyond

    OpenAIRE

    Ohya Yuji; Karasudani Takashi; Nagai Tomoyuki; Watanabe Koichi

    2017-01-01

    Wind lens is a new type of wind power system consisting of a simple brimmed ring structure that surrounds the rotor causing greater wind to pass through the turbine. As a consequence, the turbine's efficiency of capturing energy from the wind gets dramatically increased. A Wind lens turbine can generate 2–5 times the power of an existing wind turbine given at the same rotor diameter and incoming wind speed. This fluid dynamical effect is also effective in the water. We have developed 1–3 kW W...

  7. [Infections after intraocular lens surgery: implications for refractive surgery].

    Science.gov (United States)

    Taneri, S; Heiligenhaus, A

    2012-09-01

    Apart from the classical indication of removing an opaque lens that is compromising vision, extraction of the crystalline lens is gaining increasing importance as a refractive procedure. This literature review which considers the present guidelines of various ophthalmological societies and recently published studies is intended to give an estimate of the incidence of postoperative endophthalmitis and evidence-based recommendations for its prophylaxis, diagnosis, and therapy. The incidence of endophthalmitis after cataract extraction is reported to be 0.04% to 0.3% in most sizeable studies. Immediate sequential bilateral cataract surgery is internationally gaining popularity. It remains difficult to estimate whether or not the risk of endophthalmitis is affected with this approach. A toxic anterior segment syndrome (TASS) needs to be differentiated from postoperative endophthalmitis. TASS is an acute sterile inflammation after cataract surgery. Remnants of detergents and antiseptics on the surgical instruments are supposed to be main triggers. Additionally, the inappropriate preparation of solutions and antibiotics for intracameral use is considered to be a major cause. A case of TASS was also reported after implantation of an iris-fixated anterior chamber lens in a phakic eye. The cefuroxime solution that was prophylactically used in the ESCRS study and that is recommended for routine cataract surgery is not commercially available in Germany as a ready preparation for intraoperative application. Different measures are undertaken in different countries to prevent postoperative endophthalmitis, whose values are not exactly quantifiable. Antisepsis with povidone-iodine is still considered to be the component with the best evidence. For management of acute postoperative endophthalmitis, the systemic application of antibiotics is recommended in addition to their intravitreal injection. Few case reports have been published describing an infection after the implantation

  8. Anti-mirror effect: A perfect lens brings a brighter feature

    OpenAIRE

    Xu, YaDong; Du, Shengwang; Gao, Lei; Chen, Huanyang

    2010-01-01

    In this letter, we show that a perfect lens can be employed to make multiple objects appear like only one in the far field, leading to a new concept of illusion optics. Numerical simulations are performed to verify the functionalities for both passive and active objects. The conceptual device can be utilized to enhance the illumination brightness for both incoherent and coherent systems.

  9. CLASS B0631+519 : Last of the cosmic lens all-sky survey lenses

    NARCIS (Netherlands)

    York, T; Jackson, N; Browne, IWA; Koopmans, LVE; McKean, JP; Norbury, MA; Biggs, AD; Blandford, RD; de Bruyn, AG; Fassnacht, CD; Myers, ST; Pearson, TJ; Phillips, PM; Readhead, ACS; Rusin, D; Wilkinson, PN

    2005-01-01

    We report on the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the Very Large Array, the Multi-Element Radio-Linked Interferometer Network (MERLIN) and the Very Long Baseline Array (VLBA) reveals a doubly imaged flat-spectrum radio core, a doubly imaged steep-spectrum

  10. Effects of resonator input power on Kerr lens mode-locked lasers

    Indian Academy of Sciences (India)

    Department of Physics, Faculty of Sciences, Shiraz University of Technology, Shiraz, Iran ... In addition, the effect of the input power on the Kerr lens sensitivity ... So, to establish a KLM system, δ must be negative. Furthermore, it must be noted that the value of |δ| ≥ 0.5 is necessary for a. Pramana – J. Phys., Vol. 85, No.

  11. Leading Praxis: Exploring Educational Leadership through the Lens of Practice Architectures

    Science.gov (United States)

    Wilkinson, Jane; Olin, Anette; Lund, Torbjorn; Ahlberg, Ann; Nyvaller, Monica

    2010-01-01

    In this article we investigate educational leadership as a site of practice, utilising the notion of "practice architectures" as our lens. The latter shifts Etienne Wenger's more individualising notion of 'learning architectures' to a broader study of the systems and organisations that prefigure educational practices and potentially,…

  12. Approaching Knowledge Management through the Lens of the Knowledge Life Cycle: A Case Study Investigation

    Science.gov (United States)

    Fowlin, Julaine M.; Cennamo, Katherine S.

    2017-01-01

    More organizational leaders are recognizing that their greatest competitive advantage is the knowledge base of their employees and for organizations to thrive knowledge management (KM) systems need to be in place that encourage the natural interplay and flow of tacit and explicit knowledge. Approaching KM through the lens of the knowledge life…

  13. Spinning pipe gas lens revisited

    CSIR Research Space (South Africa)

    Mafusire, C

    2008-01-01

    Full Text Available The graded index (GRIN-like) medium generated by gas inside a heated steel pipe when rotated about its longitudinal axis has the ability to focus a laser beam. While the effective focal length of such a system has previously been studied...

  14. Effects of Temperature on Hybrid Lens Performance

    Science.gov (United States)

    Askins, Steve; Victoria, Marta; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2011-12-01

    In hybrid Silicone-on-glass Fresnel lenses, an optical silicone is molded onto a glass substrate and forms the Fresnel structure. These lenses offer a cost effective solution as a primary optical element in point-focus concentrator photovoltaic modules, as well as performance advantages. However, these lenses have a high performance variation with temperature due both to the change in index of refraction of silicone as well as to deformations in the facets caused by coefficient of thermal expansion (CTE) mismatch. In this study we perform measurements of the light flux at the focal plane of a family of SOG lenses, varying temperature and lens-to-receiver distances. The effect of varying silicone cure temperature and the depth of the silicone between the lens and the glass substrate on temperature dependence was investigated. A preliminary computer model of this behavior is presented.

  15. Complications caused by contact lens wearing.

    Science.gov (United States)

    Beljan, Jasna; Beljan, Kristina; Beljan, Zdravko

    2013-04-01

    Complications in wearing contact lenses are very rare and caused by poor maintenance, over-extended wear and wearing of contact lenses in a polluted environment. Regular control by a professional person can efficiently reduce the number of complications. This paper describes the most common risks factors for complications, and complications of wearing contact lenses with the classification according to the anatomic parts of the eye: eyelids, tear film, limbus, corneal epithelium, corneal stroma and corneal endothelium. Every complication has been described by the characteristic signs and symptoms, etiology and pathology, as well as therapy and prognosis. The paper describes how to select adequate customers as contact lens users, with proper education in order to ensure minimal incidence of complications due to contact lens wear, thus attracting a lot of satisfied and healthy customers.

  16. A Tribute to Dr. Willy Lens

    Directory of Open Access Journals (Sweden)

    Maarten Vansteenkiste

    2016-07-01

    Full Text Available Dr. Willy Lens, born on December 10th, 1943, passed away on August 29th, 2014. With his passing, the motivation community has lost a seminal member, a mentor, and a friend. Dr. Lens – a Fellow of the Association for Psychological Science and Founding Fellow of the American Educational Research Association – made fundamental contributions to the study of motivation both through his own work and through his caring and thoughtful mentorship of a large community of scholars. With this tribute, we want to honor Dr. Willy Lens’ significance to psychology and education as well as his positive influence, both personally and professionally, on the lives of dozens of scholars. With his contagious enthusiasm and caring mentorship, Willy was an example for our academic community and with this tribute we express our gratitude for the privilege to have collaborated with him.

  17. A polycarbonate ophthalmic-prescription lens series.

    Science.gov (United States)

    Davis, J K

    1978-08-01

    Improvements in polycarbonate material, production techniques, and scratch-resistant coatings, combined with a process-oriented design, have resulted in a precision lens series. Surface quality is comparable to that of untreated glass ophthalmic lenses. The repeatability of the process results in closely controlled axial power and off-axis performance. For most lens prescriptions, the ANSI Z80.1 optical-center specifications for prescription accuracy are maintained through a total field of view of 40 deg for an 8-mm range of center-of-rotation distances. Off-axis astigmatism is controlled for near-point seeing. The lenses are both lighter and thinner than those of crown glass. A scratch-resistant coating reduces the reflections normally associated with high-index (1.586) materials. Impact resistance exceeds that required by ANSI Z80.7 and is many times that required by ANSI Z80.1.

  18. A stereoscopic lens for digital cinema cameras

    Science.gov (United States)

    Lipton, Lenny; Rupkalvis, John

    2015-03-01

    Live-action stereoscopic feature films are, for the most part, produced using a costly post-production process to convert planar cinematography into stereo-pair images and are only occasionally shot stereoscopically using bulky dual-cameras that are adaptations of the Ramsdell rig. The stereoscopic lens design described here might very well encourage more live-action image capture because it uses standard digital cinema cameras and workflow to save time and money.

  19. Sterilization potential of contact lens solutions

    OpenAIRE

    Dada Vijay; Mehta Manoj

    1988-01-01

    In a dynamic field of Contact Lens Solutions maintenance of high standards of anti-microbial activity is a must Resterilization Activity Time′ is a universally accepted yardstick for such an evaluation. In this study eight brands of indigenous popular solutions alongwith two FDA approved solutions were tested for their sterilization efficacy: Standardized suspensions of Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus fumigatus were used for the purpose. ...

  20. Genus two Goeritz groups of lens spaces

    OpenAIRE

    Cho, Sangbum

    2012-01-01

    Given a genus-$g$ Heegaard splitting of a 3-manifold, the Goeritz group is defined to be the group of isotopy classes of orientation-preserving homeomorphisms of the manifold that preserve the splitting. In this work, we show that the Goeritz groups of genus-2 Heegaard splittings for lens spaces $L(p, 1)$ are finitely presented, and give explicit presentations of them.

  1. Studies of extraction and transport system for highly charged ion beam of 18 GHz superconducting electron cyclotron resonance ion source at Research Center for Nuclear Physics.

    Science.gov (United States)

    Yorita, T; Hatanaka, K; Fukuda, M; Ueda, H; Yasuda, Y; Morinobu, S; Tamii, A; Kamakura, K

    2014-02-01

    An 18 GHz superconducting electron cyclotron resonance ion source is installed to increase beam currents and to extend the variety of ions especially for highly charged heavy ions which can be accelerated by cyclotrons of Research Center for Nuclear Physics (RCNP), Osaka University. The beam production developments of several ions from B to Xe have been already done [T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 79, 02A311 (2008) and T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 81, 02A332 (2010)] and the further studies for those beam extraction and its transport have been done in order to increase the beam current more. The plasma electrode, extraction electrode, and einzel lens are modified. Especially extraction electrode can be applied minus voltage for the beam extraction and it works well to improve the extracted beam current. The extraction voltage dependences of transmission and emittance also have been studied for beam current improvement which is injected into azimuthally varying field cyclotron at RCNP.

  2. Pitfalls in aphakic contact lens fitting

    Directory of Open Access Journals (Sweden)

    Dada Vijay

    1990-01-01

    Full Text Available We examined 23 consecutive cases of unilateral aphakia reporting to the contact lens office for endothelial count and morphology, corneal thickness and toricity. The fellow eye served as a control in all the cases. It was found that there is a significant drop in the central endothelial cell density, and change in the size and shape of the cells. These observations indicate a thermodynamically unstable state. The aphakic corneas were thicker than the controls but not to a significant extent. The cell count and pachymetry had no statistical correlation. Toricity of the aphakic corneas make successful fitting of a lens difficult. Since prolonged use of extended wear gas permeable as well as hydrogel lenses have a deleterious effect on the endothelium it is suggested that a careful case selection be made and strict monitoting carried out at follow up. These corneas are liable for decompensation with only mild noxious stimuli. This article is intended to acquaint the ophthalmologist with the pitfalls in aphakic contact lens fitting so that a cautious follow up may be planned.

  3. Achromobacter xylosoxidans keratitis after contact lens usage.

    Science.gov (United States)

    Park, Jung Hyun; Song, Nang Hee; Koh, Jae Woong

    2012-02-01

    To report on Achromobacter xylosoxidans keratitis in two healthy patients who had worn contact lenses foran extended period of time. A 36-year-old female and a 21-year-old female visited our hospital with ocular pain and blurred vision. Both patients had a history of wearing soft contact lenses for over fve years with occasional overnight wear. At the initial presentation, a slit lamp examination revealed corneal stromal infiltrations and epithelial defects with peripheral neovascularization in both patients. Microbiological examinations were performed from samples of corneal scrapings, contact lenses, contact lens cases, and solution. The culture resulting from the samples taken from the contact lenses, contact lens cases, and solution were all positive for Achromobacter xylosoxidans. Confrming that the direct cause of the keratitis was the contact lenses, the frst patient was prescribed ceftazidime and amikacin drops sensitive to Achromobacter xylosoxidans. The second patient was treated with 0.3% gatifoxacin and fortifed tobramycin drops. After treatment, the corneal epithelial defects were completely healed, and subepithelial corneal opacity was observed. Two cases of Achromobacter xylosoxidans keratitis were reported in healthy young females who wore soft contact lenses. Achromobacter xylosoxidans should be considered a rare but potentially harmful pathogen for lens-induced keratitis in healthy hosts.

  4. Radiation dose to the eye lens

    DEFF Research Database (Denmark)

    Baun, Christina; Falch Braas, Kirsten; D. Nielsen, Kamilla

    2015-01-01

    Radiation Dose to the Eye Lens: Does Positioning Really Matter? C. Baun1, K. Falch1, K.D. Nielsen2, S. Shanmuganathan1, O. Gerke1, P.F. Høilund-Carlsen1 1Department of Nuclear Medicine, Odense University Hospital, Odense C, Denmark. 2University College Lillebaelt, Odense, Denmark. Aim: The scan...... field in oncology patients undergoing eyes-to-thighs PET/CT must always include the base of the scull according to department guidelines. The eye lens is sensitive to radiation exposure and if possible it should be avoided to scan the eye. If the patient’s head is kipped backwards during the scan one...... might avoid including the eye in the CT scan without losing sufficient visualization of the scull base. The aim of this study was to evaluate the possibility of decreasing the radiation dose to the eye lens, simply by changing the head position, when doing the PET/CT scan from the base of the scull...

  5. Compensation of Presbyopia With the Light Sword Lens.

    Science.gov (United States)

    Mira-Agudelo, Alejandro; Torres-Sepúlveda, Walter; Barrera, John F; Henao, Rodrigo; Blocki, Narcyz; Petelczyc, Krzysztof; Kolodziejczyk, Andrzej

    2016-12-01

    We present the first physiological evaluation of the use of the light sword lens (LSL) for presbyopia compensation. The LSL is an axially asymmetric optical element designed for imaging with extended depth of focus. A monocular visual simulator setup is implemented to measure visual acuity (VA). Physiological presbyopia is "mimicked" in human subjects by paralysis of the ciliary muscle, using topical application of a muscarinic antagonist. The effect of a contact lens-configured LSL on the mimicked presbyopia visual system is evaluated by measuring VA as a function of target vergence. The ability of the LSL to compensate presbyopia for 2 photopic luminance values was also analyzed. The average VA values for 11 subjects suggest that the LSL can compensate for presbyopia across a wide range of target vergences for which the LSL was designed (-3 to 0 D). However, the proposed corrector element causes a loss of distance VA. The mean logMAR VA in that target vergence range was 0.07. The VA curves also show that luminance does not affect the expected behavior of the LSL-corrected presbyopic eye. These results indicate that the LSL has significant potential as a visual aid for presbyopia.

  6. Bilateral posterior crystalline lens dislocations in an otherwise healthy child

    Directory of Open Access Journals (Sweden)

    AlShehri, Omar A.

    2017-10-01

    Full Text Available Introduction: Ectopia lentis is defined as a crystalline lens displacement, either partially or completely, due to zonular abnormalities. It can be a result of trauma, hereditary ocular disease, or part of systemic diseases, like Marfan syndrome and homocystinuria.Case description: We report a case of a medically free 16-year-old girl, who was referred to our hospital complaining of poor vision and a squint in both eyes since childhood. Her history included a traffic accident when she was one-year-old. She was previously diagnosed with alternating esotropia, which was treated with glasses, alternating patching, and bilateral Botox injections. On examination, she had a visual acuity of 6/7.5 with correction in the right eye and 6/6 with correction in the left eye. She had an esotropia of 60 prism diopters, which was partially corrected to 40 prism diopters for near and distance vision. Fundus examination showed myopic changes in each eye and dislocated lenses in the posterior pole at 6 o’clock. Our case was stable, so we used conservative management with contact lenses.Conclusion: Bilateral posterior lens dislocation is very rare. A proper examination is important and early diagnosis can prevent serious complications, such as retinal detachment or pupillary block glaucoma.

  7. Bilateral posterior crystalline lens dislocations in an otherwise healthy child.

    Science.gov (United States)

    AlShehri, Omar A; Almarzouki, Hashem; Alharbi, Badr A; Alqahtani, Mohammed; Allam, Khaled

    2017-01-01

    Introduction: Ectopia lentis is defined as a crystalline lens displacement, either partially or completely, due to zonular abnormalities. It can be a result of trauma, hereditary ocular disease, or part of systemic diseases, like Marfan syndrome and homocystinuria. Case description: We report a case of a medically free 16-year-old girl, who was referred to our hospital complaining of poor vision and a squint in both eyes since childhood. Her history included a traffic accident when she was one-year-old. She was previously diagnosed with alternating esotropia, which was treated with glasses, alternating patching, and bilateral Botox injections. On examination, she had a visual acuity of 6/7.5 with correction in the right eye and 6/6 with correction in the left eye. She had an esotropia of 60 prism diopters, which was partially corrected to 40 prism diopters for near and distance vision. Fundus examination showed myopic changes in each eye and dislocated lenses in the posterior pole at 6 o'clock. Our case was stable, so we used conservative management with contact lenses. Conclusion: Bilateral posterior lens dislocation is very rare. A proper examination is important and early diagnosis can prevent serious complications, such as retinal detachment or pupillary block glaucoma.

  8. Review of small aspheric glass lens molding technologies

    Science.gov (United States)

    Yin, Shaohui; Jia, Hongpeng; Zhang, Guanhua; Chen, Fengjun; Zhu, Kejun

    2017-03-01

    Aspheric lens can eliminate spherical aberrations, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

  9. A Wirelessly Powered Smart Contact Lens with Reconfigurable Wide Range and Tunable Sensitivity Sensor Readout Circuitry.

    Science.gov (United States)

    Chiou, Jin-Chern; Hsu, Shun-Hsi; Huang, Yu-Chieh; Yeh, Guan-Ting; Liou, Wei-Ting; Kuei, Cheng-Kai

    2017-01-07

    This study presented a wireless smart contact lens system that was composed of a reconfigurable capacitive sensor interface circuitry and wirelessly powered radio-frequency identification (RFID) addressable system for sensor control and data communication. In order to improve compliance and reduce user discomfort, a capacitive sensor was embedded on a soft contact lens of 200 μm thickness using commercially available bio-compatible lens material and a standard manufacturing process. The results indicated that the reconfigurable sensor interface achieved sensitivity and baseline tuning up to 120 pF while consuming only 110 μW power. The range and sensitivity tuning of the readout circuitry ensured a reliable operation with respect to sensor fabrication variations and independent calibration of the sensor baseline for individuals. The on-chip voltage scaling allowed the further extension of the detection range and prevented the implementation of large on-chip elements. The on-lens system enabled the detection of capacitive variation caused by pressure changes in the range of 2.25 to 30 mmHg and hydration level variation from a distance of 1 cm using incident power from an RFID reader at 26.5 dBm.

  10. Holographic display for see-through augmented reality using mirror-lens holographic optical element.

    Science.gov (United States)

    Li, Gang; Lee, Dukho; Jeong, Youngmo; Cho, Jaebum; Lee, Byoungho

    2016-06-01

    A holographic display system for realizing a three-dimensional optical see-through augmented reality (AR) is proposed. A multi-functional holographic optical element (HOE), which simultaneously performs the optical functions of a mirror and a lens, is adopted in the system. In the proposed method, a mirror that is used to guide the light source into a reflection type spatial light modulator (SLM) and a lens that functions as Fourier transforming optics are recorded on a single holographic recording material by utilizing an angular multiplexing technique of volume hologram. The HOE is transparent and performs the optical functions just for Bragg matched condition. Therefore, the real-world scenes that are usually distorted by a Fourier lens or an SLM in the conventional holographic display can be observed without visual disturbance by using the proposed mirror-lens HOE (MLHOE). Furthermore, to achieve an optimized optical recording condition of the MLHOE, the optical characteristics of the holographic material are measured. The proposed holographic AR display system is verified experimentally.

  11. Design of PSIRA with focusing lens concentrating picosecond impulse on biological target.

    Science.gov (United States)

    Petrishia, A; Sasikala, M

    2016-03-04

    The Prolate Spheroidal Impulse Radiating Antenna (PSIRA) is used to radiate very fast pulses in a narrow beam with low dispersion and high field amplitude. The PSIRA is suitable to apply fast, intense pulses without direct contact, for skin cancer treatment. In this proposed work, SWB (Slanted Wire Biconical), EPH (Elliptical Profile Horn), TSVS (Tapered Slot Vivaldi Shape) and Tapered Arm Conical Plate (TACP) feed antenna configurations for Prolate Spheroidal Reflector (PSR) are explored to enhance spatial resolution on biological targets. The feed antenna is placed at the first focal point and the target is located at the second focal point of the PSR. Next, the near field focusing lens is designed to enhance the amplitude and the resolution of the wave incident at the second focus. A 10 layer Log periodic lens system is placed before the target to reduce the spot size of the focused field on the target. The delivery of subnanosecond pulses using reflector in conjunction with and without Log periodic lens system on the biological target is compared for all feed antenna configurations. Tapered Arm Conical Plate (TACP) fed PSR with the 10 layer Log periodic lens system greatly reduces the spot size to 0.75 cm along lateral direction and 1.5 cm along axial direction. The enhancement in spatial resolution is very suitable to reduce the damage to healthy tissues during cancer treatment.

  12. Thermomechanical Assessment of the Collector for the Hollow Electron Lens

    CERN Document Server

    Anderson, George Bowers

    2017-01-01

    The hollow electron lens (HEL) is a system proposed for the High Luminosity upgrade of the Large Hadron Collider LHC (HL-LHC) [1]. Being considered for installation at LHC point 4, the HEL improves halo control and collimation of proton beams in the collider [2]. This is achieved by creating a hollow tube of electrons using an electron gun. This axisymmetric electron cloud travels around the proton beam for a few meters, overlapping with the proton beam halo, until the electron cloud is dissipated in a collector, which is the focus of this project. A 3D image of the HEL system is found in Figure 1 and a further technical description of such electron lenses is available in [3].

  13. N-cadherin regulates signaling mechanisms required for lens fiber cell elongation and lens morphogenesis.

    Science.gov (United States)

    Logan, Caitlin M; Rajakaruna, Suren; Bowen, Caitlin; Radice, Glenn L; Robinson, Michael L; Menko, A Sue

    2017-08-01

    Tissue development and regeneration involve high-ordered morphogenetic processes that are governed by elements of the cytoskeleton in conjunction with cell adhesion molecules. Such processes are particularly important in the lens whose structure dictates its function. Studies of our lens-specific N-cadherin conditional knockout mouse (N-cadcKO) revealed an essential role for N-cadherin in the migration of the apical tips of differentiating lens fiber cells along the apical surfaces of the epithelium, a region termed the Epithelial Fiber Interface (EFI), that is necessary for normal fiber cell elongation and the morphogenesis. Studies of the N-cadcKO lens suggest that N-cadherin function in fiber cell morphogenesis is linked to the activation of Rac1 and myosin II, both signaling pathways central to the regulation of cell motility including determining the directionality of cellular movement. The absence of N-cadherin did not disrupt lateral contacts between fiber cells during development, and the maintenance of Aquaporin-0 and increased expression of EphA2 at cell-cell interfaces suggests that these molecules may function in this role. E-cadherin was maintained in newly differentiating fiber cells without interfering with expression of lens-specific differentiation proteins but was not able to replace N-cadherin function in these cells. The dependence of migration of the fiber cell apical domains along the EFI for lens morphogenesis on N-cadherin provides new insight into the process of tissue development. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. FEM simulation of the human lens compared to ex vivo porcine lens cutting pattern: a possible treatment of presbyopia

    Science.gov (United States)

    Ripken, T.; Breitenfeld, P.; Fromm, M.; Oberheide, U.; Gerten, G.; Lubatschowski, H.

    2006-02-01

    The most probable reason for presbyopia is an age related loss of elasticity of the lens. It progresses typically during the whole life and at the age of about 45 it leads to a considerable loss of the ability to accommodate within the next decade. However, both, the ciliary muscle and the lens capsule stay active and elastic, respectively. With respect to this, one concept is to regain the deformability of the lens without changing the capsule or zonular apparatus. Since the investigations of Ripken et al. proofed that the flexibility of the presbyopic lens tissue can be increased through the creation of fs-laser induced microcuts inside the lens, this is one possible approach to treat presbyopia. On this account a finite-element-method model with ANSYS of the human lens during accommodation will be presented. The analysis premises all lens materials to be linear elastic and allow large displacements. A first analysis of this method for the treatment of presbyopia is accomplished. Therefore the mechanical analysis of untreated and treated lens are compared. In addition ex-vivo elasticity measurements of untreated and treated lenses will be presented. As a result an improvement of the flexibility of the lens tissue is found and as its consequence a change of the lens radii of curvature is established. After suitable processing of the output data the change in optical power between untreated and treated lenses are calculated. The finite element simulation shows similar behaviour compared to the treated porcine lenses.

  15. Camera, handlens, and microscope optical system for imaging and coupled optical spectroscopy

    Science.gov (United States)

    Mungas, Greg S. (Inventor); Boynton, John (Inventor); Sepulveda, Cesar A. (Inventor); Nunes de Sepulveda, legal representative, Alicia (Inventor); Gursel, Yekta (Inventor)

    2012-01-01

    An optical system comprising two lens cells, each lens cell comprising multiple lens elements, to provide imaging over a very wide image distance and within a wide range of magnification by changing the distance between the two lens cells. An embodiment also provides scannable laser spectroscopic measurements within the field-of-view of the instrument.

  16. Achieving high focusing power for a large-aperture liquid crystal lens with novel hole-and-ring electrodes.

    Science.gov (United States)

    Chiu, Chi-Wei; Lin, Yu-Cheng; Chao, Paul C-P; Fuh, Andy Y-G

    2008-11-10

    Aiming to equip commercial camera modules, such as the optical imaging systems with a CMOS sensor module in 3 Mega pixels, an ultra thin liquid crystal lens with designed hole-and-ring electrodes is proposed in this study to achieve high focusing power. The LC lens with proposed electrodes improves the central intensity of electric field which leads to better focusing quality. The overall thickness of the LC lens can be as thin as 1.2 mm and the shortest focal length of the 4 mm-aperture lens occurs at 20 cm under an applied voltage of 30 V at 1 KHz. The inner ring electrode requires only 40% of applied voltage of the external hole electrode. The applied voltages for this internal ring and external hole electrodes can simply be realized by a pre-designed parallel resistance pair and a single voltage source. Experiments are conducted for validation and it shows that the designed LC lens owns good image clearness and contrast at the focal plane. The proposed design reduces the thickness of LC lens and is capable of achieving relative higher focusing power than past studies with lower applied voltage.

  17. APPROACH TO AUTOMATION OF LENS COMPONENTS CENTERING FOR ASSEMBLING OF DIFFERENT DESIGN OBJECTIVES

    Directory of Open Access Journals (Sweden)

    A. Y. Pimenov

    2016-01-01

    Full Text Available Subject of Research.Existing adjustment methods of lens objectives in two mechanical designs have been analyzed, the main ways of centering error compensation have been considered. The algorithm of automated search of optical elements position has been developed based on the existing methods of centering for compensation of residual decentering. The methods of joint application of this algorithm and centering machine “Trioptics Opticentric” have been suggested. Method. Centering errors of the objective lens components are measured on the centering machine. Aberrations of optical system are calculated by using the received data of centering errors entered to the objective mathematical model. For the calculation of aberration compensation, iteration algorithm of searching of optical elements optimal position is used. The image quality is analyzed for each obtained realization of the optical system. The result of program performance is data matrix about optical components location such that compensation of residual aberrations occurs. Based on the obtained information the system assembling is carried out with the use of centering machine “Trioptics Opticentric”. Main Results. Computer modeling of centering errors for 100 lens apochromatic objectives of drop-in mountings lens design has been carried out. The coma of object axial point image has been chosen as quality estimation criterion. The developed algorithm has been applied for the worst realization of the optical system. In this case the value of integral coma of object axial point image has been decreased by two orders and reduced practically to zero. It is noted that the modeling of adjustment process via using the algorithm of automated search enables to predict the possibility of objective assembly with required quality parameters. Practical Relevance. The received results can be applied on the lines of automated assembly of modern lens objectives.

  18. Cytokeratin in lens epithelial cells and its effect on anterior lens capsule opacification.

    Science.gov (United States)

    Budo, C; Montanus, F; Goffinet, G; Goossens, G; Gaill, F

    1993-05-01

    Postoperative lens capsule opacification is a complication of extracapsular cataract extraction. To avoid this problem, we aspirated the epithelial cells lining the internal surface of the capsular bag. Anterior capsule specimens collected three and six years after the first surgical intervention (extracapsular cataract extraction with intercapsular implantation of a poly[methyl methacrylate] intraocular lens) and in vitro studies of epithelial cell cultures revealed the presence of intracellular and extracellular cytokeratin. After several years, the cytokeratin layers were arranged in a pattern analogous to that of liquid crystalline phases and many nonhuman extraocular tissues.

  19. Multipoint photonic doppler velocimetry using optical lens elements

    Science.gov (United States)

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

    A probe including a fisheye lens is disclosed to measure the velocity distribution of a moving surface along many lines of sight. Laser light, directed to the surface and then reflected back from the surface, is Doppler shifted by the moving surface, collected into fisheye lens, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to an index-matching lens and eventually to a fisheye lens. The fiber array flat polished and coupled to the index-matching lens using index-matching gel. Numerous fibers in a fiber array project numerous rays through the fisheye lens which in turn project many measurement points at numerous different locations to establish surface coverage over a hemispherical shape with very little crosstalk.

  20. Geometry-invariant GRIN lens: iso-dispersive contours.

    Science.gov (United States)

    Bahrami, Mehdi; Goncharov, Alexander V

    2012-07-01

    A dispersive model of a gradient refractive index (GRIN) lens is introduced based on the idea of iso-dispersive contours. These contours have constant Abbe number and their shape is related to iso-indicial contours of the monochromatic geometry-invariant GRIN lens (GIGL) model. The chromatic GIGL model predicts the dispersion throughout the GRIN structure by using the dispersion curves of the surface and the center of the lens. The analytical approach for paraxial ray tracing and the monochromatic aberration calculations used in the GIGL model is employed here to derive closed-form expressions for the axial and lateral color coefficients of the lens. Expressions for equivalent refractive index and the equivalent Abbe number of the homogeneous equivalent lens are also presented and new aspects of the chromatic aberration change due to aging are discussed. The key derivations and explanations of the GRIN lens optical properties are accompanied with numerical examples for the human and animal eye GRIN lenses.

  1. Forensic Analysis of a Contact Lens in a Murder Case.

    Science.gov (United States)

    Zwerling, Charles S

    2016-03-01

    Contact lenses have had rare relevance in trials and/or investigations. After 5 years of burial, orbital remnants were retrieved from an exhumed body and subsequently identified as a key piece of material evidence in a murder trial. The exhumed case materials were evaluated under laboratory conditions and were determined to be contact lens remnants. Contact lens fracture and burial simulation studies were performed to provide additional corroboration of the physical findings of the exhumed contact lens remnants. This material evidence was instrumental in providing factual proof refuting the defendant's testimony in the murder trial. A brief history of contact lens composition and use is provided for understanding the methods and observational results. This forensic case study represents the first published documentation of a contact lens from an exhumed body being used in a murder investigation and establishes an operational procedure for future forensic contact lens examinations. © 2016 American Academy of Forensic Sciences.

  2. The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

    Science.gov (United States)

    Park, Suhyun; Yoon, Heechul; Larin, Kirill V.; Emelianov, Stanislav Y.; Aglyamov, Salavat R.

    2017-02-01

    Intraocular pressure (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic wave velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic wave velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear wave elasticity imaging. To generate and then image the elastic wave propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic wave velocity in the cornea increased from 0.96  ±  0.30 m s-1 to 6.27  ±  0.75 m s-1 as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic wave velocity in the crystalline lens with the minimum and the maximum speeds of 1.44  ±  0.27 m s-1 and 2.03  ±  0.46 m s-1, respectively. This study shows that ultrasound shear wave elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.

  3. The Sloan Lens ACS Survey. XIII. Discovery of 40 New Galaxy-scale Strong Lenses

    Science.gov (United States)

    Shu, Yiping; Brownstein, Joel R.; Bolton, Adam S.; Koopmans, Léon V. E.; Treu, Tommaso; Montero-Dorta, Antonio D.; Auger, Matthew W.; Czoske, Oliver; Gavazzi, Raphaël; Marshall, Philip J.; Moustakas, Leonidas A.

    2017-12-01

    We present the full sample of 118 galaxy-scale strong-lens candidates in the Sloan Lens ACS (SLACS) Survey for the Masses (S4TM) Survey, which are spectroscopically selected from the final data release of the Sloan Digital Sky Survey. Follow-up Hubble Space Telescope (HST) imaging observations confirm that 40 candidates are definite strong lenses with multiple lensed images. The foreground-lens galaxies are found to be early-type galaxies (ETGs) at redshifts 0.06–0.44, and background sources are emission-line galaxies at redshifts 0.22–1.29. As an extension of the SLACS Survey, the S4TM Survey is the first attempt to preferentially search for strong-lens systems with relatively lower lens masses than those in the pre-existing strong-lens samples. By fitting HST data with a singular isothermal ellipsoid model, we find that the total projected mass within the Einstein radius of the S4TM strong-lens sample ranges from 3 × 1010 M ⊙ to 2 × 1011 M ⊙. In Shu et al., we have derived the total stellar mass of the S4TM lenses to be 5 × 1010 M ⊙ to 1 × 1012 M ⊙. Both the total enclosed mass and stellar mass of the S4TM lenses are on average almost a factor of 2 smaller than those of the SLACS lenses, which also represent the typical mass scales of the current strong-lens samples. The extended mass coverage provided by the S4TM sample can enable a direct test, with the aid of strong lensing, for transitions in scaling relations, kinematic properties, mass structure, and dark-matter content trends of ETGs at intermediate-mass scales as noted in previous studies. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. These observations are associated with HST program #12210.

  4. Strategies for the prevention of contact lens-related Acanthamoeba keratitis: a review.

    Science.gov (United States)

    Carnt, Nicole; Stapleton, Fiona

    2016-03-01

    Acanthamoeba keratitis is a severe, often sight threatening, corneal infection which in Western countries is predominantly seen in daily wear of contact lenses. This review aims to summarise the pathobiology and epidemiology of contact lens-related Acanthamoeba keratitis, and to present strategies for prevention, particularly with respect to modifiable risk factors in contact lens wear. The virulence of Acanthamoeba and resistance to treatment in keratitis appears to be linked with the production of a low molecular weight protease MIP133 by the organism, in response to binding to corneal epithelial cells through a mannose binding protein, and to the ability of the organism to convert from the trophozoite to the resistant cyst form. Recent epidemiological studies in contact lens relate disease have confirmed the link between solution topping up and Acanthamoeba keratitis and have reinforced the importance of avoidance of tap water, either as part of the care for the contact lens or storage case, handling lenses with wet hands or showering while wearing lenses. In the most recent analysis from the USA, there were no strong effects for solution type, water source or water disinfection process. Wearer age, lens wear time and history to appear to be linked with Acanthamoeba keratitis. Daily disposable contact lens use would be expected to reduce the prevalence of Acanthamoeba disease although this is unproven. While Acanthamoeba keratitis remains challenging to diagnose and manage, strategies to limit the disease severity in contact lens wearers should include attention to recently identified risk factors, particularly those related to water contact. Public health awareness measures, the use of daily disposable contact lenses, a better understanding of the contribution of the host immunity and the development of standardised methods for culture of amoeba and testing of contact lens care systems against Acanthamoeba in the licensing process may be of value. Alternative

  5. A physically-based approach for lens flare simulation

    OpenAIRE

    Keshmirian, Arash

    2008-01-01

    In this thesis, we present a physically-based method for the computer graphics simulation of lens flare phenomena in photographic lenses. The proposed method can be used to render lens flares from nearly all types of lenses regardless of optical construction. The method described in this thesis utilizes the photon mapping technique (Jensen, 2001) to simulate the flow of light within the lens, and captures the visual effects of internal reflections and scattering within (and between) the optic...

  6. Geometry-invariant GRIN lens: iso-dispersive contours

    OpenAIRE

    Bahrami, Mehdi; Goncharov, Alexander V.

    2012-01-01

    A dispersive model of a gradient refractive index (GRIN) lens is introduced based on the idea of iso-dispersive contours. These contours have constant Abbe number and their shape is related to iso-indicial contours of the monochromatic geometry-invariant GRIN lens (GIGL) model. The chromatic GIGL model predicts the dispersion throughout the GRIN structure by using the dispersion curves of the surface and the center of the lens. The analytical approach for paraxial ray tracing and the monochro...

  7. Lens growth and protein changes in the eastern grey kangaroo

    OpenAIRE

    Augusteyn, Robert C.

    2011-01-01

    Purpose Development in marsupials takes place predominantly ex utero while the young is attached to a nipple in the mother?s pouch, very different from that in other species. This study was undertaken to examine whether this affects lens growth and the production of lens proteins in kangaroos. Methods Fresh lenses were obtained at official culls from eastern gray kangaroos (Macropus giganteus). Wet weights were recorded for all and protein contents were determined for one lens from each anima...

  8. Lens regeneration in mice under the influence of vitamin A

    Indian Academy of Sciences (India)

    The effect of vitamin A has been studied on lens regeneration in young (7 days old) as well as adult mice. A longitudinal slit was made under local anesthesia in the cornea over the lens. The lens was extracted intact through the incision. Intraperitonial injection of vitamin A (0.05 ml of 30 IU/ml in young and 0.05 ml of 50 ...

  9. Intraocular lens fixation with Dacron mesh: Part II.

    Science.gov (United States)

    Peyman, G A; Koziol, J; Janevicius, R

    1977-08-01

    We studied the feasibility of fixation of an intraocular lens in the posterior chamber by utilizing Dacron mesh to stimulate cellular ingrowth from the posterior iris surface. Tissue ingrowth into the Dacron mesh occurred five days after Dacron implantation and a firm adhesion between Dacron and the iris developed in a consistent and localized manner. Dacron fibers, when placed in contact with the posterior iris surface, induce fibroblastic and pigmented epithelial tissue ingrowth around the fibers. Fixation of the lens with and without the posterior lens capsule and vitreous is compared in vitrectomized and nonvitrectomized eyes. It is possible to achieve fixation without support from the posterior lens capsule and vitreous.

  10. Lubricant effects on low Dk and silicone hydrogel lens comfort.

    Science.gov (United States)

    Ozkan, Jerome; Papas, Eric

    2008-08-01

    To investigate the influence of three lubricants of varying viscosity, on postinsertion and 6 h comfort with contact lens wear. Comfort and associated symptoms of dryness were assessed in 15 experienced contact lens wearers. Subjects wore a low Dk lens in one eye and a silicone hydrogel in the other and participated in four separate trials involving no lubricant (baseline), saline, and two commercially available lubricants of differing viscosity. The in-eye lubricants were used immediately following lens insertion and every 2 h postinsertion for a 6 h wear period. Postlens insertion comfort was significantly better for both lens types when lubricants or saline were used compared with no lubricant use. After 6 h lens wear, comfort was influenced by lens type and not by in-eye lubricant or saline use. Also after 6 h lens wear, less dryness sensation was reported for silicone hydrogel lenses when using lubricants but not saline. Although lubricant use does help reduce dryness symptoms with silicone hydrogel lens wear, there appears to be minimal longer-term benefit to comfort. Furthermore, increased lubricant viscosity did not lead to improved longer-term comfort.

  11. 600 Volt Stretched Lens Array for Solar Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ENTECH, Auburn, NASA, and others have recently developed a new space photovoltaic array called the Stretched Lens Array (SLA), offering unprecedented performance...

  12. Further studies of contact lens motion during blinking.

    Science.gov (United States)

    Conway, H D; Knoll, H A

    1986-10-01

    Contact lens motion is felt to be of increasing importance in connection with debris elimination, particularly in extended wear lenses. Thus an improved analysis is made of a simple model for investigating the initial motion of a hard contact lens over the eye during blinking. It is shown that the assumption of constant tear film thickness is a reasonable one. This greatly simplifies the analysis. Various vertical force vs. time variations are considered and lens velocity/time graphs and maximum lens displacement calculated. These are in good agreement with the results of experiment.

  13. Lentil (Lens culinaris) Lipid Transfer Protein Len c 3: A Novel Legume Allergen

    NARCIS (Netherlands)

    Akkerdaas, J.; Finkina, E. I.; Balandin, S. V.; Santos Magadán, S.; Knulst, A.; Fernandez-Rivas, M.; Asero, R.; van Ree, R.; Ovchinnikova, T. V.

    2012-01-01

    Background: Lentils are increasingly consumed in many parts of the world. Two allergens, Len c 1 and 2, have been reported previously. Recently, peanut and green bean lipid transfer proteins (LTPs) have been identified as the first two members of an important group of allergens that might be

  14. LENS: web-based lens for enrichment and network studies of human proteins.

    Science.gov (United States)

    Handen, Adam; Ganapathiraju, Madhavi K

    2015-01-01

    Network analysis is a common approach for the study of genetic view of diseases and biological pathways. Typically, when a set of genes are identified to be of interest in relation to a disease, say through a genome wide association study (GWAS) or a different gene expression study, these genes are typically analyzed in the context of their protein-protein interaction (PPI) networks. Further analysis is carried out to compute the enrichment of known pathways and disease-associations in the network. Having tools for such analysis at the fingertips of biologists without the requirement for computer programming or curation of data would accelerate the characterization of genes of interest. Currently available tools do not integrate network and enrichment analysis and their visualizations, and most of them present results in formats not most conducive to human cognition. We developed the tool Lens for Enrichment and Network Studies of human proteins (LENS) that performs network and pathway and diseases enrichment analyses on genes of interest to users. The tool creates a visualization of the network, provides easy to read statistics on network connectivity, and displays Venn diagrams with statistical significance values of the network's association with drugs, diseases, pathways, and GWASs. We used the tool to analyze gene sets related to craniofacial development, autism, and schizophrenia. LENS is a web-based tool that does not require and download or plugins to use. The tool is free and does not require login for use, and is available at http://severus.dbmi.pitt.edu/LENS.

  15. Septic lens implantation syndrome in a cat.

    Science.gov (United States)

    Dalesandro, Nicole; Stiles, Jean; Miller, Margaret

    2011-09-01

    A 13-year-old female spayed domestic shorthair cat was presented initially for a change in the appearance of the left eye. On initial examination, a small penetrating wound was suspected as the cause for a corneal scar, an anterior cortical incipient cataract and mild iritis. The cat was not re-presented until 1 year later at which time ocular pain was marked. Severe anterior uveitis and glaucoma were diagnosed and the eye enucleated. Histopathology documented intralenticular coccoid bacteria and septic lens implantation syndrome. © 2011 American College of Veterinary Ophthalmologists.

  16. Hollow Electron Lens Simulation for the SPS

    CERN Document Server

    Previtali, V; Stancari, G; Valishev, A

    2013-01-01

    The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations

  17. Rat silicone hydrogel contact lens model: effects of high- versus low-Dk lens wear.

    Science.gov (United States)

    Zhang, Yunfan; Gabriel, Manal M; Mowrey-McKee, Mary F; Barrett, Ronald P; McClellan, Sharon; Hazlett, Linda D

    2008-11-01

    This study used a rat contact lens (CL) model to test if high- versus low-Dk lens wear caused changes in (1) conjunctival Langerhans cell (LC) number or location; (2) Bcl-2 expression; and (3) infection risk. Female, Lewis rats wore a high- or low-Dk CL continuously for 2 weeks. Afterward, corneas were harvested and processed for ADPase activity to identify LCs, for immunostaining and for real time-polymerase chain reaction. Contact lens-wearing rats also were challenged with Pseudomonas aeruginosa by placing a bacterial-soaked CL on the eye followed by topical delivery of bacteria. After 48 hrs, slit lamp examination and real time-polymerase chain reaction were used to evaluate the corneal response. Conjunctival LC were significantly increased after low- versus high-Dk CL wear (PDk lens wearing group. Bcl-2 mRNA levels were significantly decreased in low- versus high-Dk CL wearing rats, while Bax, FasL, caspase 3, and caspase 9 levels were unchanged. Immunostaining for Bcl-2 showed fewer positively stained epithelial cells in the low- versus high-Dk lens wearing group. After bacterial challenge, 30% of low- versus none of the high-Dk CL wearing corneas became infected and showed increased mRNA levels for several proinflammatory cytokines/chemokines, inducible nitric oxide synthase and matrix metalloproteinase-9. Low- versus high-Dk or non-CL wear led to an increased number of conjunctival LC, decreased Bcl-2 levels, and increased the risk of bacterial infection.

  18. Fusarium and Candida albicans biofilms on soft contact lenses: model development, influence of lens type and susceptibility to lens care solutions

    Science.gov (United States)

    Fungal keratitis is commonly caused by Fusarium species, while cases of Candida-associated keratitis are less frequent. Recent outbreaks of Fusarium keratitis were associated with contact lens wear and with MoistureLoc contact lens care solution, and biofilm formation on contact lens/lens cases was...

  19. The eyelids and tear film in contact lens discomfort.

    Science.gov (United States)

    Siddireddy, Jaya Sowjanya; Vijay, Ajay Kumar; Tan, Jacqueline; Willcox, Mark

    2017-10-17

    To investigate characteristics of the eyelid margins, meibomian glands and the tear film of contact lens wearers, and to determine whether these characteristics were related to symptoms of contact lens discomfort. A cross sectional study was performed on thirty existing daily wear soft contact lens wearers (6 male; 24 female) with median age of 23 years (range 18-41). Eyelid signs and tear film characteristics were evaluated during a single visit and subjects completed the contact lens and dry eye questionnaire (CLDEQ-8) to evaluate ocular discomfort. Based on the CLDEQ-8 responses, subjects were classified as symptomatic (n=17) or asymptomatic (n=13). Grades of foam at meibomian gland orifices (3±1), expressibility (2±1) and quality of secretions (2±1), tear evaporation rate with (112±54g/m(2)/h) or without (88±45g/m(2)/h) contact lens wear, fluorescein tear breakup time (8±2 seconds) and tear lipid layer thickness (45±17nm) were significantly associated with symptoms of discomfort in symptomatic lens wearers only (r(2)>0.45; p value<0.05). Upper lid-wiper epitheliopathy, meibomian gland acini reflectivity and tear meniscus height showed significant correlations with comfort scores in both symptomatic and asymptomatic contact lens wearers (p<0.05). A greater number of Demodex mites was also observed in the upper eyelid of symptomatic lens wearers (2±1) compared to asymptomatic lens wearers (0±0; p value=0.042). Morphological irregularities of the meibomian glands and alterations to tear film secretions that affect tear evaporative dynamics were associated with symptoms of discomfort amongst the symptomatic lens wearers. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  20. The linear Fresnel lens - Solar optical analysis of tracking error effects

    Science.gov (United States)

    Cosby, R. M.

    1977-01-01

    Real sun-tracking solar concentrators imperfectly follow the solar disk, operationally sustaining both transverse and axial misalignments. This paper describes an analysis of the solar concentration performance of a line-focusing flat-base Fresnel lens in the presence of small transverse tracking errors. Simple optics and ray-tracing techniques are used to evaluate the lens solar transmittance and focal-plane imaging characteristics. Computer-generated example data for an f/1.0 lens indicate that less than a 1% transmittance degradation occurs for transverse errors up to 2.5 deg. In this range, solar-image profiles shift laterally in the focal plane, the peak concentration ratio drops, and profile asymmetry increases with tracking error. With profile shift as the primary factor, the ninety-percent target-intercept width increases rapidly for small misalignments, e.g., almost threefold for a 1-deg error. The analytical model and computational results provide a design base for tracking and absorber systems for the linear-Fresnel-lens solar concentrator.

  1. The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations.

    Science.gov (United States)

    Bimurzaev, S B; Aldiyarov, N U; Yakushev, E M

    2017-10-01

    The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field. Two of the simplest versions of the corrector are considered: a corrector with a two-electrode electrostatic mirror and a corrector with a three-electrode electrostatic mirror. It is shown that using the two-electrode mirror one can eliminate either spherical or chromatic aberration of the objective lens, without changing the value of its linear magnification. Using a three-electrode mirror, it is possible to eliminate spherical and chromatic aberrations of the objective lens simultaneously, which is especially important in designing electron microscopes with extremely high resolution. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Detecting the spatial chirp signals by fractional Fourier lens with transformation materials

    Science.gov (United States)

    Chen, J.; Hu, J.

    2018-02-01

    Fractional Fourier transform (FrFT) is the general form of the Fourier transform and is an important tool in signal processing. As one typical application of FrFT, detecting the chirp rate (CR, or known as the rate of frequency change) of a chirp signal is important in many optical measurements. The optical FrFT that based on graded index lens fails to detect the high CR chirp because the short wave propagation distance of the impulse in the lens will weaken the paraxial approximation condition. With the help of transformation optics, the improved FrFT lens is proposed to adjust the high CR as well as the impulse location of the given input chirp signal. The designed transformation materials can implement the effect of space compression, making the input chirp signal is equivalent to have lower CR, therefore the system can satisfy the paraxial approximation better. As a result, this lens can improve the detection precision for the high CR. The numerical simulations verified the design. The proposed device may have both theoretical and practical values, and the design demonstrates the ability and flexibility of TO in spatial signal processing.

  3. The Role of Type IV Collagen in Developing Lens in Mouse Fetuses

    Directory of Open Access Journals (Sweden)

    Mehdi Jalali

    2009-09-01

    Full Text Available Objective(sExtracellular matrix (ECM and basement membrane (BM play important roles in many developmental processes during development and after birth. Among the components of the BM, collagen fibers specially type IV are the most important parts. The aim of this study was to determine the time when collagen type IV appears in the BM of lens structure during mouse embryonic development.Materials and MethodsIn this experimental study, 22 female Balb/C mice were randomly selected and were kept under normal condition, finding vaginal plug was assumed as day zero of pregnancy. From embryonic day 10 to 20, all specimens were sacrificed by cervical dislocation and their heads were fixed, serially sectioned and immunohistochemistry study for tracing collagen type IV in lens were carried out.ResultsOur data revealed that collagen type IV appeared at the early stage of gestation day 12 in BM of anterior epithelial lens cells and the amount of this protein gradually increased until days 15-17 in ECM and posterior capsule epithelium. After this period, severe reaction was not observed in any part of the lens.ConclusionThese findings establish the important role of collagen IV in developing optic cup and any changes during critical period of pregnancy may be result in severe visual system defect

  4. PLASMA LENS FOR US BASED SUPER NEUTRINO BEAM AT EITHER FNAL OR BNL.

    Energy Technology Data Exchange (ETDEWEB)

    HERSHCOVITCH,A.; WENG, W.; DIWAN, M.; GALLARDO, J.; KIRK, H.; JOHNSON, B.; KAHN, S.; GARATE, E.; VAN DRIE, A.; ROSTOKER, N.

    2007-06-25

    The plasma lens concept is examined as an alternative to focusing horns and solenoids for a neutrino beam facility. The concept is based on a combined high-current lens/target configuration. Current is fed at an electrode located downstream from the beginning of the target where pion capturing is needed. The current is carried by plasma outside the target. A second plasma lens section, with an additional current feed, follows the target. The plasma is immersed in a relatively small solenoidal magnetic field to facilitate its current profile shaping to optimize pion capture. Simulations of the not yet fully optimized configuration yielded a 25% higher neutrino flux at a detector situated at 3 km from the target than the horn system for the entire energy spectrum and a factor of 2.47 higher flux for neutrinos with energy larger than 3 GeV. A major advantage of plasma lenses is in background reduction. In anti-neutrino operation, neutrino background is reduced by a factor of close to 3 for the whole spectrum, and for and for energy larger than 3 GeV, neutrino background is reduced by a factor of 3.6. Plasma lenses have additional advantages: larger axial currents, high signal purity: minimal neutrino background in anti-neutrino runs. The lens medium consists of plasma, consequently, particle absorption and scattering is negligible. Withstanding high mechanical and thermal stresses in a plasma is not an issue.

  5. INVESTIGATION OF PARALLAX ISSUES FOR MULTI-LENS MULTISPECTRAL CAMERA BAND CO-REGISTRATION

    Directory of Open Access Journals (Sweden)

    J. P. Jhan

    2017-08-01

    Full Text Available The multi-lens multispectral cameras (MSCs, such as Micasense Rededge and Parrot Sequoia, can record multispectral information by each separated lenses. With their lightweight and small size, which making they are more suitable for mounting on an Unmanned Aerial System (UAS to collect high spatial images for vegetation investigation. However, due to the multi-sensor geometry of multi-lens structure induces significant band misregistration effects in original image, performing band co-registration is necessary in order to obtain accurate spectral information. A robust and adaptive band-to-band image transform (RABBIT is proposed to perform band co-registration of multi-lens MSCs. First is to obtain the camera rig information from camera system calibration, and utilizes the calibrated results for performing image transformation and lens distortion correction. Since the calibration uncertainty leads to different amount of systematic errors, the last step is to optimize the results in order to acquire a better co-registration accuracy. Due to the potential issues of parallax that will cause significant band misregistration effects when images are closer to the targets, four datasets thus acquired from Rededge and Sequoia were applied to evaluate the performance of RABBIT, including aerial and close-range imagery. From the results of aerial images, it shows that RABBIT can achieve sub-pixel accuracy level that is suitable for the band co-registration purpose of any multi-lens MSC. In addition, the results of close-range images also has same performance, if we focus on the band co-registration on specific target for 3D modelling, or when the target has equal distance to the camera.

  6. Investigation of Parallax Issues for Multi-Lens Multispectral Camera Band Co-Registration

    Science.gov (United States)

    Jhan, J. P.; Rau, J. Y.; Haala, N.; Cramer, M.

    2017-08-01

    The multi-lens multispectral cameras (MSCs), such as Micasense Rededge and Parrot Sequoia, can record multispectral information by each separated lenses. With their lightweight and small size, which making they are more suitable for mounting on an Unmanned Aerial System (UAS) to collect high spatial images for vegetation investigation. However, due to the multi-sensor geometry of multi-lens structure induces significant band misregistration effects in original image, performing band co-registration is necessary in order to obtain accurate spectral information. A robust and adaptive band-to-band image transform (RABBIT) is proposed to perform band co-registration of multi-lens MSCs. First is to obtain the camera rig information from camera system calibration, and utilizes the calibrated results for performing image transformation and lens distortion correction. Since the calibration uncertainty leads to different amount of systematic errors, the last step is to optimize the results in order to acquire a better co-registration accuracy. Due to the potential issues of parallax that will cause significant band misregistration effects when images are closer to the targets, four datasets thus acquired from Rededge and Sequoia were applied to evaluate the performance of RABBIT, including aerial and close-range imagery. From the results of aerial images, it shows that RABBIT can achieve sub-pixel accuracy level that is suitable for the band co-registration purpose of any multi-lens MSC. In addition, the results of close-range images also has same performance, if we focus on the band co-registration on specific target for 3D modelling, or when the target has equal distance to the camera.

  7. Cosmological Constraints from Gravitational Lens Time Delays

    Science.gov (United States)

    Coe, Dan; Moustakas, Leonidas A.

    2009-11-01

    Future large ensembles of time delay (TD) lenses have the potential to provide interesting cosmological constraints complementary to those of other methods. In a flat universe with constant w including a Planck prior, The Large Synoptic Survey Telescope TD measurements for ~4000 lenses should constrain the local Hubble constant h to ~0.007 (~1%), Ω de to ~0.005, and w to ~0.026 (all 1σ precisions). Similar constraints could be obtained by a dedicated gravitational lens observatory (OMEGA) which would obtain precise TD and mass model measurements for ~100 well-studied lenses. We compare these constraints (as well as those for a more general cosmology) to the "optimistic Stage IV" constraints expected from weak lensing, supernovae, baryon acoustic oscillations, and cluster counts, as calculated by the Dark Energy Task Force. TDs yield a modest constraint on a time-varying w(z), with the best constraint on w(z) at the "pivot redshift" of z ≈ 0.31. Our Fisher matrix calculation is provided to allow TD constraints to be easily compared to and combined with constraints from other experiments. We also show how cosmological constraining power varies as a function of numbers of lenses, lens model uncertainty, TD precision, redshift precision, and the ratio of four-image to two-image lenses.

  8. Scleral lens for keratoconus: technology update

    Directory of Open Access Journals (Sweden)

    Rathi VM

    2015-10-01

    Full Text Available Varsha M Rathi,1 Preeji S Mandathara,2 Mukesh Taneja,1 Srikanth Dumpati,1 Virender S Sangwan1 1L V Prasad Eye Institute, Hyderabad, India; 2School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia Abstract: Scleral lenses are large diameter lenses which rest over the sclera, unlike the conventional contact lenses which rest on the cornea. These lenses are fitted to not touch the cornea and there is a space created between the cornea and the lens. These lenses are inserted in the eyes after filling with sterile isotonic fluid. Generally, scleral contact lenses are used for high irregular astigmatism as seen in various corneal ectatic diseases such as keratoconus, pellucid marginal degeneration, or/and as liquid bandage in ocular surface disorders. In this article, we review the new developments, that have taken place over the years, in the field of scleral contact lenses as regard to new designs, materials, manufacturing technologies, and fitting strategies particularly for keratoconus. Keywords: keratoconus, scleral lens, technology update, PROSE

  9. Contact lens-related acanthamoeba keratitis.

    Science.gov (United States)

    Stapleton, Fiona; Ozkan, Jerome; Jalbert, Isabelle; Holden, Brien A; Petsoglou, Con; McClellan, Kathy

    2009-10-01

    Acanthamoeba keratitis is a rare but severe disease, with more than 95% of cases occurring in contact lens wearers. With a worldwide resurgence of contact lens-related disease, this report illustrates the clinical characteristics and treatment challenges representative of this disease. This report describes Acanthamoeba keratitis in a 47-year-old female using extended wear silicone hydrogel contact lenses, with a history of swimming in a home pool and failure to subsequently disinfect the contact lenses. The diagnosis was based on clinical signs, disease course, and confocal microscopy results despite a negative result for corneal smear and culture. The corneal signs included an epithelial defect, epithelial irregularities, anterior stromal infiltrates, perineural infiltrates, an anterior stromal ring infiltrate, and hypopyon. The case was diagnosed as an infective keratitis and treated promptly using intensive topical administration of fortified gentamicin and cephalothin. The high likelihood Acanthamoeba prompted immediate use of polyhexamethylbiguanide and chlorhexidine, with propamide and adjunct treatment using atropine and oral diclofenac. Steroids were added on day 3, and the frequency of administration of antibacterial treatment was gradually reduced and ceased by day 10. The analgesia was stopped at 3 months. The frequency of administration of antiamoeba therapy and steroid treatment was slowly reduced and all treatment was ceased after 18 months. Despite considerable morbidity in terms of the treatment duration, hospitalization, outpatient appointments, and associated disease costs, the final visual outcome (6/6) was excellent.

  10. Convex Lens-Induced Nanoscale Templating

    Science.gov (United States)

    Berard, Daniel; Michaud, Francois; McFaul, Christopher; Mahsid, Sara; Reisner, Walter; Leslie, Sabrina

    2014-03-01

    We demonstrate a new platform, ``Convex Lens-Induced Nanoscale Templating'' (CLINT), for dynamic manipulation and trapping of single DNA molecules. In the CLINT technique, the curved surface of a convex lens is used to deform a flexible coverslip above a substrate containing embedded nanotopography, creating a nanoscale gap that can be adjusted during an experiment to confine molecules within the embedded nanostructures. Critically, CLINT has the capability of actively transforming a macroscale flow-cell into a nanofluidic device without need for high-temperature direct bonding, leading to ease of sample loading and greater accessibility of the surface. Moreover, as DNA molecules present in the gap will be driven into the embedded topography from above, CLINT eliminates the need for the high pressures or electric fields necessitated by direct bonded nanofluidic devices for loading DNA in the confined structures. To demonstrate the versatility of CLINT, we confine DNA to nanogroove structures, demonstrating DNA nanochannel-based stretching. Using ionic strengths that are in line with typical biological buffers, we have successfully extended DNA in sub 30nm nanochannels, achieving high stretching (90%) that is in good agreement with Odijk deflection theory.

  11. Non-Invasive Early Detection and Molecular Analysis of Low X-ray Dose Effects in the Lens

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, Lee [Boston University

    2014-07-02

    This is the Final Progress Report for DOE-funded research project DE-PS02-08ER08-01 titled “Non-Invasive Early Detection and Molecular Analysis of Low X-ray Dose Effects in the Lens”. The project focuses on the effects of low-linear energy transfer (LET) radiation on the ocular lens. The lens is an exquisitely radiosensitive tissue with a highly-ordered molecular structure that is amenable to non-invasive optical study from the periphery. These merits point to the lens as an ideal target for laser-based molecular biodosimetry (MBD). Following exposure to different types of ionizing radiations, the lens demonstrates molecular changes (e.g., oxidation, racemization, crosslinkage, truncation, aggregation, etc.) that impact the structure and function of the long-lived proteins in the cytosol of lens fiber cells. The vast majority of proteins in the lens comprise the highly-ordered crystallins. These highly conserved lens proteins are amongst the most concentrated and stable in the body. Once synthesized, the crystallins are retained in the fiber cell cytoplasm for life. Taken together, these properties point to the lens as an ideal system for quantitative in vivo MBD assessment using quasi-elastic light scattering (QLS) analysis. In this project, we deploy a purpose-designed non-invasive infrared laser QLS instrument as a quantitative tool for longitudinal assessment of pre-cataractous molecular changes in the lenses of living mice exposed to low-dose low-LET radiation compared to non-irradiated sham controls. We hypothesize that radiation exposure will induce dose-dependent changes in the molecular structure of matrix proteins in the lens. Mechanistic assays to ascertain radiation-induced molecular changes in the lens focus on protein aggregation and gene/protein expression patterns. We anticipate that this study will contribute to our understanding of early molecular changes associated with radiation-induced tissue pathology. This study also affords potential for

  12. Isofocusing and immunological investigations on cephalopod lens proteins

    NARCIS (Netherlands)

    Brahma, S.K.; Lancieri, M.

    1979-01-01

    Soluble lens proteins from Octopus vulgaris, Sepia officinalis, and Loligo vulgaris were analyzed by thin-layer isoelectric focusing and compared by various immunochemical methods using antibodies directed against total soluble lens protein antigens from the said three species. The results show

  13. 21 CFR 886.1415 - Ophthalmic trial lens frame.

    Science.gov (United States)

    2010-04-01

    ...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1415 Ophthalmic trial lens frame. (a) Identification. An opthalmic trial lens frame is a mechanical device intended to hold trial lenses for vision testing. (b) Classification. Class I (general controls). The device is exempt from the premarket...

  14. Incidence of contact lens-associated microbial keratitis

    NARCIS (Netherlands)

    Cheng, K.H.; Leung, S.L.; Hoekman, J.W.; Beekhuis, W.H.; Mulder, P.G.H.; Geerards, A.J.M.; Kijlstra, A.

    1999-01-01

    Background. The incidence of contact-lens-associated microbial keratitis is uncertain and its related morbidity in the general population of contact-lens wearers is not known. We examined these issues in a prospective epidemiological study. Methods. We surveyed all practising ophthalmologists in the

  15. Cytokine changes in tears and relationship to contact lens discomfort.

    Science.gov (United States)

    Willcox, Mark D P; Zhao, Zhenjun; Naduvilath, Thomas; Lazon de la Jara, Percy

    2015-01-01

    To determine the reproducibility of a multiplex bead assay for measuring cytokines in tears and correlations between ocular discomfort with or without contact lens wear and the concentration of cytokines in tears. Ninety participants (divided into two groups) were enrolled in this prospective study. They were asked to rate their ocular comfort and collect their tears in the morning and just before sleep for 10 days with or without contact lenses. The participants collected their tears using a glass microcapillary tube for both stages. Galyfilcon A lenses were worn on a daily disposable basis during the contact lens stage, and comfort scores and tears were collected before lens insertion and prior to lens removal at the end of the day. Tears were analyzed for cytokine concentrations using a 27-plex multibead assay. Correlations were sought between cytokine concentrations and comfort. There was a significant (pocular comfort over the day with or without lens wear. The magnitude of ocular discomfort was significantly greater (p-0.5 Log pg/ml, p-0.2 Log pg/ml, ptears was correlated to ocular comfort, but this was not changed by contact lens wear. Ocular comfort during the day is magnified by contact lens wear. However, the increase in the change in comfort during lens wear was not associated with changes in 15 cytokines in the tear film.

  16. Optimal lens design and use in laser-scanning microscopy.

    NARCIS (Netherlands)

    Negrean, A.; Mansvelder, H.D.

    2014-01-01

    In laser-scanning microscopy often an off-the-shelf achromatic doublet is used as a scan lens which can reduce the available diffraction-limited field-of-view (FOV) by a factor of 3 and introduce chromatic aberrations that are scan angle dependent. Here we present several simple lens designs of

  17. 21 CFR 800.10 - Contact lens solutions; sterility.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Contact lens solutions; sterility. 800.10 Section 800.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL Requirements for Specific Medical Devices § 800.10 Contact lens solutions; sterility. (a)(1) Informed medical opinion is...

  18. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable...

  19. 21 CFR 886.5925 - Soft (hydrophilic) contact lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Soft (hydrophilic) contact lens. 886.5925 Section 886.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5925 Soft (hydrophilic) contact lens. (a) Identification. A soft (hydrophilic)...

  20. 21 CFR 886.1385 - Polymethylmethacrylate (PMMA) diagnostic contact lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polymethylmethacrylate (PMMA) diagnostic contact lens. 886.1385 Section 886.1385 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1385 Polymethylmethacrylate (PMMA) diagnostic contact lens. (...