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Dissertations / Theses on the topic 'Lens'
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1
Yan, Yufeng. "Photographic Fisheye Lens Design for 35mm Format Cameras." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613395.
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Fisheye lenses refer to ultra-wide angle lenses that have field of view equal or larger than 180 degrees. Such lenses introduce large amount of barrel distortion to capture at least the entire hemisphere in front of the lens. Fisheye lenses were initially designed for scientific use, such as cloud recording and angle measuring, and were widely used for commercial purposes later. The development of photographic fisheye lenses started in 1960s. However, the lack of detailed references on photographic fisheye lens design makes such design challenging. This thesis provides detailed introduction of photographic fisheye lens design for 35mm format DSLR cameras. A discussion on the history of fisheye lenses is provided to describe the development of fisheye lenses. The tangential and sagittal magnifications are mathematically derived for each fisheye lens projection mapping method to show their differences. The special properties and design issues of photographic fisheye lenses are described in detail. Along with each design issue, some solutions suggested by the author are also provided. The performance of the current diagonal fisheye lenses for 35mm DSLR cameras are evaluated in detail. Then a new diagonal fisheye lens designed by the author is presented and compared with the current diagonal fisheye lenses on the market. Finally, a zoom fisheye lens designed for 35mm DSLR cameras is presented and discussed.
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Shepard, III Ralph Hamilton. "Metamaterial Lens Design." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194734.
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Developments in nanotechnology and material science have produced optical materials with astonishing properties. Theory and experimentation have demonstrated that, among other properties, the law of refraction is reversed at an interface between a naturally occurring material and these so-called metamaterials. As the technology advances metamaterials have the potential to vastly impact the field of optical science.In this study we provide a foundation for future work in the area of geometric optics and lens design with metamaterials. The concept of negative refraction is extended to derive a comprehensive set of first-order imaging principles as well as an exhaustive aberration theory to 4th order. Results demonstrate congruence with the classical theory; however, negative refraction introduces a host of novel properties. In terms of aberration theory, metamaterials present the lens designer with increased flexibility. A singlet can be bent to produce either positive or negative spherical aberration (regardless of its focal length), its contribution to coma can become independent of its conjugate factor, and its field curvature takes on the opposite sign of its focal power. This is shown to be advantageous in some designs such as a finite conjugate relay lens; however, in a wider field of view landscape lens we demonstrate a metamaterial's aberration properties may be detrimental.This study presents the first comprehensive investigation of metamaterial lenses using industry standard lens design software. A formal design study evaluates the performance of doublet and triplet lenses operating at F/5 with a 100 mm focal length, a 20° half field of view, and specific geometric constraints. Computer aided optimization and performance evaluation provide experimental controls to remove designer-induced bias from the results. Positive-index lenses provide benchmarks for comparison to metamaterial systems subjected to identical design constraints. We find that idiosyncrasies in a metamaterial lens' aberration content can be exploited to produce imaging systems that are superior to their conventional counterparts. However, in some circumstances the reduced low-order aberration content in a metamaterial lens reduces the effectiveness of aberration balancing and stop shifting. Through a series of design experiments the relative advantages and challenges of using metamaterials in lens design are revealed.
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Shams-Ul-Bari, Naveed. "Isospectral orbifold lens spaces." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23981.
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Spectral theory is the study of Mark Kac's famous question [K], "can one hear the shape of a drum?" That is, can we determine the geometrical or topological properties of a manifold by using its Laplace Spectrum? In recent years, the problem has been extended to include the study of Riemannian orbifolds within the same context. In this thesis, on the one hand, we answer Kac's question in the negative for orbifolds that are spherical space forms of dimension higher than eight. On the other hand, for the three-dimensional and four-dimensional cases, we answer Kac's question in the affirmative for orbifold lens spaces, which are spherical space forms with cyclic fundamental groups. We also show that the isotropy types and the topology of the singularities of Riemannian orbifolds are not determined by the Laplace spectrum. This is done in a joint work with E. Stanhope and D. Webb by using P. Berard's generalization of T. Sunada's theorem to obtain isospectral orbifolds. Finally, we construct a technique to get examples of orbifold lens spaces that are not isospectral, but have the same asymptotic expansion of the heat kernel. There are several examples of such pairs in the manifold setting, but to the author's knowledge, the examples developed in this thesis are among the first such examples in the orbifold setting.
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Yuan, Sheng. "Aberrations of Anamorphic Optical Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195267.
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A detailed study of the aberrations of anamorphic optical systems is presented. This study has been developed with a theoretical structure similar to that of rotationally symmetric optical systems (RSOS) and can be considered a generalization.A general method of deriving the monochromatic primary aberration coefficient expressions for any anamorphic system types with double plane symmetry has been provided.The complete monochromatic primary aberration coefficient expressions for cylindrical anamorphic systems, toroidal anamorphic systems and general anamorphic systems with aspheric departure have been presented, in a form similar to the Seidel aberrations of RSOS.Some anamorphic image system design examples are provided that illustrate the use and value of the theory developed.
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Wilson, Cynthia Nicole. "A Fully Customizable Anatomically Correct Model of the Crystalline Lens." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20130.
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The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.
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Kumar, Bharat. "The Mechanobiology of the Crystalline Lens." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587649113548924.
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Ollinger, Christoph German Josef. "A waveguide-based lens-less x-ray microscope." Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/ollinger.
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Sasián, José. "Joseph Petzval lens design approach." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627184.
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Gao, Weichuan, and Jose Sasian. "Air lens vs aspheric surface: a lens design case study." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627181.
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We discuss the behavior of air lenses in lens design. The structural aberration coefficients of a thin air lens are derived and compared with their glass thin lens counterpart. Examples are provided for a telephoto lens and the Monochromatic Quartet where air lenses or aspheric surfaces are used.
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DePianto, Daryle Joseph. "Studies on lens fiber cell gene expression & lens differentiation /." Connect to Digital dissertations. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Shu, Daisy Yao. "TGFβ, BMP and EGF interplay in the pathogenesis of fibrotic cataract: a tale of three growth factors." Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20493.
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The ocular lens is bathed by a cocktail of growth factors, such as fibroblast growth factor (FGF), bone morphogenetic protein (BMP), insulin-like growth factor (IGF), epidermal growth factor (EGF) and transforming growth factor-beta (TGFβ) that differentially influence cellular behaviour. While some growth factors such as FGF, BMP and EGF facilitate normal physiological lens processes, TGFβ is unique in that it is a potent inducer of lens cell pathology, namely, epithelial-mesenchymal transition (EMT) leading to fibrotic cataract formation. The studies in this thesis primarily explore the intracellular signalling pathways regulating TGFβ2-induced EMT in the ocular lens using an established rat lens epithelial explant system. We first investigate the role of BMP-7 in antagonising TGFβ2-driven EMT through differential activation of the canonical Smad signalling pathway. We then explore the role of TGFβ-signalling leading to the transactivation of EGF receptor (EGFR) signalling and show how EGFR-signalling forms an integrated network with ERK1/2/MAPK- and Smad-signalling. This led us to examine the role of EGF in augmenting the TGFβ-induced EMT response, through a shift in the activation profiles of TGFβ-induced EGFR-, ERK1/2/MAPK- and Smad-signalling. We conclude by characterising a human anterior subcapsular cataract specimen, and applying a human lens epithelial explant system to translate some of the findings from the rodent model to human. By culturing the normally discarded anterior lens capsulorhexis material obtained during human cataract surgery, we showcase a human model for TGFβ-induced EMT that presents with a striking morphological and biochemical resemblance to our established rodent model. By characterising the roles of downstream intracellular TGFβ-signalling pathways and how they go on to form an integrated network, we endeavour to better understand lens EMT and thus develop effective pharmaceutical alternatives for cataract prevention.
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Yang, Dingjie. "The Network Lens." Thesis, Linnaeus University, School of Computer Science, Physics and Mathematics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-6626.
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A complex network graphics may be composed of hundreds and thousands of objects, such as nodes and edges. Each object may hold a large number of attributes that might be difficult to explore in the network visualization. Therefore, many visualization tools and approaches have been developed to gain more information from the network graphics. In this paper, we introduce the concept of the Network Lens, a new widget that assists the users to deal with a complex network. The Network Lens is an interactive tool that combines data visualization to a magic lens. With the help of the Network Lens, users can display hidden information of the elements in the network graphics based on their interest. Moreover, the Network Lens supports a series of interactive functions that give the users flexible options to define their own lenses.
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Weir, I. J. M. "The thermal lens." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372116.
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Amador, Lui. "Deslanting the Lens." Scholarship @ Claremont, 1999. http://scholarship.claremont.edu/cgu_etd/93.
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Deslanting the Lens examines the historical and sociological implications of how Asian men have been represented in popular American film. From the early days of “yellowface” to caricatures like Long Duck Dong, Asian men have been relegated to perpetual foreigner status in American cinema. This paper will explore why the portrayal of Asian men has been limited to very specific ideas about Asian and Asian Americans are in society. This analysis will also include how socio/political events have shaped and influence popular perceptions about Asians, that inform how Asian men continue to be depicted in film.
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Crouch, Izzy. "Beyond the Lens." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1245.
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Beyond the Lens is a portrait series combining visual images with audiotaped recordings of eight Scripps seniors’ narration of their personal, academic and interpersonal process during the course of their college career. This capstone project seeks to uncover the dynamic nature of the Scripps College community by highlighting the unique evolution of these eight individuals. With this project, I hope to convey that while there is no one specific mold for a Scripps student, there are common threads in the development of key characteristics which propel these participants toward their next steps, among them courage to pursue leadership roles, compassion for underrepresented groups both locally and globally, confidence to make positive changes in their fields of interest and a profound engagement and commitment to their immediate and extended communities. Beyond the Lens not only guides the viewer into the makings of each of these student’s individual profiles but also helps the viewer understand better how the Scripps community shapes their personal ambitions, creating fertile ground for lasting impact. Through the interview process, I examine the enduring imprint of an historically all-women’s college environment, exploring disparate and common threads within each student's experiences, including the effects of in-depth exploration and articulation of multiple perspectives and theoretical positions within academic and non-academic exchanges. Moreover, in these conversations, I ask each student to consider both positive and negative elements of their community and to reflect on their holistic experience at the College in and outside of the classroom. While this capstone is a minute representation of the Scripps community as a whole, it nonetheless provides a glimpse into the influences and processes at play within Scripps College. I aim to demonstrate that being a Scripps student means that we, as a community, are pressed to delve beyond the limited representations so pervasive in our current media soaked lives toward a more complex understanding of ever-evolving forces that occur within ourselves, other members of our community and society at large.
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Nichols, Jason Jay. "Evaporative tear film and contact lens factors associated with dry eye symptoms in contact lens wearers." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1085771728.
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Hott, John Lester. "Photochemical alterations of ocular lens proteins." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30087.
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Sasian, Jose, and Yufeng Yan. "Miniature camera lens design with a freeform surface." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627187.
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We present a miniature camera lens design method that uses a freeform surface based on the pedal curve to the ellipse in polynomial form. Two designs are presented and their benefits of optical performance and tolerance sensitivity are compared to designs with conventional aspheric surfaces. We also reverse a freeform design using even aspherical surfaces to show that the optimization solution of a freeform design cannot be reproduced by even aspherical surfaces.
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Stapleton, Fiona J. "The pathogenesis and epidemiology of contact lens related disease in cosmetic contact lens wearers." Thesis, City University London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280544.
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Rueff, Erin M. "Contact Lens Discomfort, Vision Correction Preferences, and Accommodative Treatment in Presbyopic and Non-Presbyopic Contact Lens Wearers." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1529583462118691.
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Moore, Lori Briggs. "Defining Ray Sets for the Analysis of Lenslet-Based Optical Systems Including Plenoptic Cameras and Shack-Hartmann Wavefront Sensors." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332894.
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Plenoptic cameras and Shack-Hartmann wavefront sensors are lenslet-based optical systems that do not form a conventional image. The addition of a lens array into these systems allows for the aberrations generated by the combination of the object and the optical components located prior to the lens array to be measured or corrected with post-processing. This dissertation provides a ray selection method to determine the rays that pass through each lenslet in a lenslet-based system. This first-order, ray trace method is developed for any lenslet-based system with a well-defined fore optic, where in this dissertation the fore optic is all of the optical components located prior to the lens array. For example, in a plenoptic camera the fore optic is a standard camera lens. Because a lens array at any location after the exit pupil of the fore optic is considered in this analysis, it is applicable to both plenoptic cameras and Shack-Hartmann wavefront sensors. Only a generic, unaberrated fore optic is considered, but this dissertation establishes a framework for considering the effect of an aberrated fore optic in lenslet-based systems. The rays from the fore optic that pass through a lenslet placed at any location after the fore optic are determined. This collection of rays is reduced to three rays that describe the entire lenslet ray set. The lenslet ray set is determined at the object, image, and pupil planes of the fore optic. The consideration of the apertures that define the lenslet ray set for an on-axis lenslet leads to three classes of lenslet-based systems. Vignetting of the lenslet rays is considered for off-axis lenslets. Finally, the lenslet ray set is normalized into terms similar to the field and aperture vector used to describe the aberrated wavefront of the fore optic. The analysis in this dissertation is complementary to other first-order models that have been developed for a specific plenoptic camera layout or Shack-Hartmann wavefront sensor application. This general analysis determines the location where the rays of each lenslet pass through the fore optic establishing a framework to consider the effect of an aberrated fore optic in a future analysis.
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Valley, Pouria. "FLAT LIQUID CRYSTAL DIFFRACTIVE LENSES WITH VARIABLE FOCUS AND MAGNIFICATION." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/145737.
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Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2πzone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm²/2mλ, where r(m) is mth zone radius, and λ is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (±2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera phones. A business plan centered on this technology was developed as part of the requirements for the minor in entrepreneurship from the Eller College of Management. An industrial analysis is presented in this study that involves product development, marketing, and financial analyses (Appendix I).
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Tagliaferri, Angela. "Risk Factors for Contact Lens Induced Papillary Conjunctivitis Associated with Silicone Hydrogel Contact Lens Wear." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1339094018.
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Selby, Alastair Phillip. "Nanoindentation of soft contact lens materials." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/nanoindentation-of-soft-contact-lens-materials(502085d8-3325-4ea8-926c-ad75b15a557d).html.
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The launch of silicone hydrogel contact lenses has led to a rise in the incidence of mechanically-related clinical complications, which is thought to be due to the increased stiffness of these materials compared to conventional hydrogel lens materials. The mechanical characteristics of hydrogel contact lenses have traditionally been investigated using tensile testing which investigated the bulk material characteristics. This thesis presents a study intended to establish a repeatable method for local mechanical measurement of hydrogel contact lenses using nanoindentation. Hydrogel materials in phosphate buffered saline were indented using a Hysitron Triboindenter mounted on a Veeco Explorer AFM using Triboscope software (version 3.5a) with a specially constructed wet cell. A model hydrogel (poly(HEMA-MMA)) was used to validate the methodology and investigate a the effect of controlled change in specimen thickness. A range of commercially available hydrogel contact lenses were then characterised (including conventional and silicone hydrogel lenses) using the same method. Two different analytical techniques were employed to determine the mechanical properties data; elastic analysis and a time-dependent viscoelastic analytical technique.A strong influence of specimen thickness on apparent mechanical properties was seen with the elastic analysis and an empirical relationship was derived to correct for this which was found to be appropriate for all contact lens specimens studied and reported in the thesis. The viscoelastic analysis results were more complex and exhibited a less clear influence of specimen thickness. However, as this is a very simple approximation as contact lenses are suspected to be poroelastic rather than viscoelastic this work could not be fully resolved in the scope of this thesis. For all contact lenses analysed, nanoindentation produced data similar to that found with conventional tensile testing, however, there was evidence for a slight dependence of elastic properties across the lens that does not correlate with sample thickness. This thesis shows the development of a way of accounting for the variation of thickness of a range of contact lenses, and demonstrated that traditional analysis is accurate enough to determine local differences in modulus across contact lenses. The viscoelastic analysis may be more appropriate for hydrogels, however, it produced irregularities that will require further work to fully resolve.
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Jamali, Afsoon Jamali. "LARGE AREA TUNABLE LIQUID CRYSTAL LENS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1541671894328594.
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Dye, Simon. "Gravitational lens mass reconstruction." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/27964.
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A highly desirable technique sought after by cosmology is one which enables the accurate mass measurement of rich galaxy clusters. From observations of their abundance and primarily their mass, clusters give strong constraints on the density parameter of the Universe, models of structure formation and normalisation of the power spectrum of density fluctuations. Gravitational lensing provides such a technique. Prevailing over X-ray temperature and virial velocity methods known to be problematic, lensing permits determination of cluster masses independent of dynamical state. This thesis concentrates mainly on the exploitation of the magnification properties of lenses rather than those of shear analysis which relies upon the quantification of galaxy image distortions. Magnification allows absolute mass measurements, breaking the sheet-mass degeneracy experienced by shear. To this extent, a theoretical analysis of the geometrical magnification of angular separations between galaxies lying behind a lensing cluster is performed. This sees application to the cluster Abell 1689 using V and I band observations to select background galaxies based on their V-I colour. The distribution of source number counts in the observed field of view results in the determination of a radial mass profile and a mass map for Abell 1689. This predicts a projected mass interior to 0.24h-1Mpc of M (< 0.24h-1Mpc) = (0.50 ± 0.09) x 1015h-1M. A new method of directly determining accurate, self-consistent lens mass and shear maps in the strong lensing regime from magnification is presented. The method relies upon pixellization of the surface mass density distribution which generates a simple, solvable set of equations. The concept of pixellization is also directed at shear analysis to give rise to a simplified method of application. Through use of cluster models, the method is verified before the magnification data from the colour-selected number counts is input to compute a self-consistent mass map of Abell 1689. The property of lens magnification to amplify observed background source fluxes is investigated. Using an independent set of observations in nine optically chosen filters, photometric redshifts of objects lying in the field of Abell 1689 are calculated. In addition to providing an unambiguous distinction between cluster members, foreground objects and background sources this also enables computation of the source luminosity function. Comparison of this with the distribution of luminosities in an observed offset field quantifies the lens-induced flux magnification to arrive at an independent mass profile measurement of Abell 1689. A projected mass interior to 0.25h-1Mpc of M(< 0.25h-1Mpc) = (0.48 ± 0.16) x 1015h-1M is found.
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McDermott, Joshua D. "The ovine lens cytoskeleton." Lincoln University, 2007. http://hdl.handle.net/10182/700.
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The lens of the eye is a vital tissue in the visual system, responsible for the collection and focusing of light on to the retina. Comprised of epithelial cells at differing stages of differentiation, the transparency of the lens is dependent on the highly ordered crystalline structure of lens proteins. The lens consists of several proteins including crystallins (α, β, γ) that make up 90% of the soluble protein, and the lens cytoskeletal proteins. Cytoskeletal proteins contribute only a fraction of the total lens protein, but are thought to play an important role in the establishment and maintenance of transparency. Calpain-induced degradation of these proteins may be involved in the development of cataracts. This has been an area of research at Lincoln University where a flock of sheep genetically predisposed to cataract maintained as a cataract development model. The aim of this research was to investigate the distribution of cytoskeletal proteins in the lens, and to examine the effects of calpain proteolysis on these proteins, with the goal of establishing the role of the lens cytoskeletal proteins in the ovine cataract model. A combination of techniques was used including immunohistochemistry, which required the development of a specific protocol for ovine lenses. Cytoskeletal proteins were identified using immunohistochemistry in lens tissue sections and exhibited characteristic distributions. Actin displayed preferential distribution in the short sides of the fibre cells in the cortex of the lens but was absent in the lens nucleus, while spectrin in the cortex and nucleus was associated with the fibre cell membrane. Filensin was observed in the outer cortex of lens sections associated with the fibre cell membrane and cytoplasm, although the pattern of localisation was indistinct due to the abundance of filensin breakdown products. Vimentin displayed membrane and cytoplasmic association in the outer cortex that diminished toward the lens nucleus, with membrane associated vimentin only persisting in the deeper regions of the cortex and nucleus. Additionally, the effect of novel calpain inhibitors (Cat0059 and Cat811) in preventing proteolysis of lens cytoskeletal protein was investigated and compared with calpain inhibitors developed elsewhere (SJA6017). The inhibitors were tested at between 10 and 0.1 μM (100 nM). All inhibitors were effective at 10 μM. SJA6017 provided significant protection to vimentin at 1 μM. Cat0059 was found to protect spectrin and filensin at 1 μM, but not vimentin, while inhibitor Cat811 was found to protect spectrin only. SJA6017 added to assays at 100 nM offered significant protection to spectrin, and Cat0059 was found to protect filensin and spectrin to a significant degree at 100 nM, indicating the novel inhibitors were comparable to those developed elsewhere in terms of their effectiveness. Taken together, the evidence presented in this thesis shows the cytoskeletal proteins as crucial elements in the lens. Their pervasive presence coupled with evidence that lens cytoskeletal proteins are sensitive to calpain-induced proteolysis that is inhibited with novel calpain inhibitors suggests that the lens cytoskeletal proteins may be useful targets in cataract prevention for future research.
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Sparrow, John Martin. "The lens in diabetes." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238162.
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Tomlinson, Richard J. "Lens design for manufacture." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/14554.
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The manufacture of complete optical systems can be broken down into three distinct stages; the optical and mechanical design, the production of both optical and mechanical components and finally their assembly and test. The three stages must not be taken in isolation if the system is to fulfil its required optical performance at reasonable cost. This report looks first at the optical design phase. There are a number of different optical design computer packages on the market that optimise an optical system for optical performance. These packages can be used to generate the maximum manufacturing errors, or tolerances, which are permissible if the system is to meets its design requirement. There is obviously a close relationship between the manufacturing tolerances and the cost of the system, and an analysis of this relationship is presented in this report. There is also an attempt made to optimise the design of a simple optical system for cost along with optical performance. Once the design is complete the production phase begins and this report then examines the current techniques employed in the manufacture, and testing of optical components. There are numerous methods available to measure the surface form generated on optical elements ranging from simple test plates through to complex interferometers. The majority of these methods require the element to be removed from the manufacturing environment and are therefore not in-process techniques that would be the most desirable. The difficulties surrounding the measurement of aspheric surfaces are also discussed. Another common theme for the non-contact test techniques is the requirement to have a test or null plate which can either limit the range of surfaces the designer may chose from or increase the cost of the optical system as the test surface will first have to be manufactured. The development of the synthetic aperture interferometer is presented in this report. This technique provides a non-contact method of surface form measurement of aspheric surfaces without needing null or test plates. The final area to be addressed is the assembly and test stage. The current assembly methods are presented, with the most common industry standard method being to fully assemble the optical system prior to examining its performance. Also, a number of active alignment techniques are discussed including whether the alignment of the individual optical elements is checked, and if need be adjusted, during the assembly phase. In general these techniques rely upon the accuracy of manufacture of the mechanical components to facilitate the optical alignment of the system. Finally a computer aided optical alignment technique is presented which allows the optical alignment of the system to be brought within tolerance prior to the cementing in place of an outer casing. This method circumvents the need for very tight manufacturing tolerances on the mechanical components and also removes the otherwise labour intensive task of assembling and disassembling an optical system until the required level of performance is achieved.
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Matos, Lennia, and Dora Herrera. "Willy Lens (1940 - 2014)." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/100137.
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Maytham-Bailey, Sandra. "One lens three views." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/6844.
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This document explores the complexity of the Zulu Reed Dance in the context of creating a photographic record of the event in various narrative styles within the genre of documentary photography. The authorphotographer acknowledges their subjective contribution in the image making process, and uses this understanding to demonstrate a continuum of subjectivity that operates depending on the visual narrative being constructed. To contextualise the photographers approach, the document explores the social, political and economic landscape, and the dominant visual record produced by media. A qualitative review of six national newspapers demonstrates that the media view is relatively generic and does not attempt to engage with alternative perspectives. The document also explores critical theory on the subject of the qualification of a photographer to provide an accurate record outside of their cultural status. The author considers the validity of image production and the reception of the work as indicative of a continuum of subjectivity. To demonstrate this fluidity, the photographer produces three photo essays, all made at the same event at the same time with very different narrative outcomes. These photo essays can be found the accompanying book titled 'One lens three views'.
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Vidarsson, Freysteinn Vidar. "Dual Polarized Geodesic Lens." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286825.
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Gradient-index (GRIN) lens antennas, such as the Luneburg lens, posses attractive electromagnetic properties. The smooth change in refractive index ensures no internal reflections and the focusing of the electromagnetic waves results in a directive antenna. The main challenge of the design of a GRIN lens is acquiring the required refractive index. Two dimensional dielectric lenses can be realized using 3 dimensional homogeneous surfaces eliminating the challenge of discritizating the continuous change in refractive index. These type of lenses are commonly referred to as geodesic lenses. In this thesis a dual polarized geodesic lens antenna is presented. The antenna consists of two metal plates that form a parallel plate waveguide (PPW) section which is deformed to mimic the behaviour of a Luneburg lens. The antenna operates in the Ka band and polarizer unit cells are employed to alter the polarization state of the antenna. The polarizers are placed in a circular configuration in the flare of the antenna to maintain a compact design and good scanning range. Eleven waveguide feeds are used with 10° separation resulting in a scanning range of ±50° in the azimuth plane. The final design is a lens antenna with a center frequency of 28 GHz and 20 % bandwidth. Simulations of the design show reflection coefficients below -15 dB and crosstalk below -17 dB. The total efficiency at 28 GHz is 90 % and above 85 % for the full frequency band.Lutningsindex-linsantenner (GRIN), till exempel Luneburg-linsen, har attraktiva elektromagnetiska egenskaper. Den jämna förändringen i brytningsindexet garanterar att inga interna reflektioner inträffar och fokuset av de elektromagnetiska vågorna resulterar i en direkt antenn. Den största utmaningen att utforma en GRIN-lins är att bestämma de brytningsindexen som behövs. Plana linser kan man förverkliga med användning av tredimensionella homogena ytor som eliminerar utmaningen att diskretisera den kontinuerliga förändringen i brytningsindex. Denna typ av lins kallas geodetisk lins. I detta examensarbete är en dubbelpolariserad geodetisk linsantenn designad. Antennen består av två metallplattor som bildar en parallell platt vågledare som är deformerad för att efterlikna beteendet hos en Luneburg-lins. Antennen fungerar i Ka- bandet och har polarisator enhetsceller för att ändra antennens polarisationstillstånd. Polarisatorerna placeras i en cirkulär konfiguration i antennen för att bibehålla en kompakt design och ett bra skanningsområde. Elva vågledare används med 10° separation vilket resulterar i ett skanningsområde på ±50° i azimutplanet. Den slutliga designen är en linsantenn med en mittfrekvens på 28 GHz och 20 % bandbredd. Simuleringar av designen visar reflektionskoefficienter under -15 dB och crosstalk under -17 dB. Den totala effektiviteten vid 28 GHz är 90 % och över 85 % för hela frekvensbandet.
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Vice, President Research Office of the. "The Lens of Language." Office of the Vice President Research, The University of British Columbia, 2008. http://hdl.handle.net/2429/2669.
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McClure, Kate Alexandra. "Tear Film Dynamics Associated with Contact Lens Wear." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523579680091666.
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Wang, Zaiqi. "Lens calcium homeostasis and selenite cataract." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042006-164509/.
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Ferreira, Daniele Alves. "Reactions using whole cell biocalytic lens culinaris (lentil)." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8566.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThis paper describes the use of seeds of lentil (Lens culinaris) as intact plant system in biocatalytic reactions of reduction and hydrolysis. Initially, some plant sources were evaluated for their action in the biocatalytic reduction of aromatic ketone acetophenone. The plants that showed positive results in the reduction reaction underwent determination of their protein content by the methods of Lowry and Bradford. Lens culinaris was plant species revealed that most relevant biocatalytic activity, in agreement with their high protein content (1.33 mg / mL and 1.07 mg / mL according to Bradford and Lowry methods, respectively), and thus The plant was selected for further study. Subsequently, always using the model substrate acetophenone as the reaction parameters were optimized: concentration of biocatalyst; reaction kinetics; stirring speed the reaction medium. After selecting these parameters, the bioreduction reactions were extended to other derivatives of prochiral acetophenone, which were observed with bioconversions yields and enantiomeric excess (ee) ranging from low to high percentages. Generally, were observed steric and electronic influences due to the type and relative position of the various substituents on aromatic compounds. In the case of substrates containing two different functional groups susceptible to reduction, low chemoselectivity observed. Investigated also other carbonyl compounds such as aliphatic and aromatic ketones, aromatic aldehydes and aromatic nitro compounds. In addition investigated the possibility that hydrolytic action from compounds belonging functions esters, amides and nitriles. The yields of the reactions were calculated using Gas Chromatography coupled with Mass Spectrometry (GC-MS) and Nuclear Magnetic Resonance Hydrogen (1H NMR). The enantiomeric excess (ee) were determined by High Performance Liquid Chromatography (HPLC) equipped with chiral columns.
Este trabalho relata a utilizaÃÃo das sementes de lentilha (Lens culinaris) como sistema Ãntegro de planta em reaÃÃes biocatalÃticas de reduÃÃo e hidrÃlise. Inicialmente, algumas fontes vegetais foram avaliadas quanto sua aÃÃo biocatalÃtica na reduÃÃo da cetona aromÃtica acetofenona. Os vegetais que revelaram resultados positivos na reaÃÃo de reduÃÃo foram submetidos à determinaÃÃo do seu teor de proteÃnas atravÃs dos mÃtodos de Lowry e Bradford. Lens culinaris foi à espÃcie vegetal que revelou atividade biocatalÃtica mais relevante, em acordo com seu alto teor de proteÃna (1,33 mg/mL e 1,07 mg/mL, segundo os mÃtodos de Bradford e Lowry, respectivamente), e assim, foi o vegetal selecionado para estudos mais aprofundados. Posteriormente, utilizando sempre a acetofenona como substrato modelo foram otimizados os parÃmetros reacionais: concentraÃÃo do biocatalisador; cinÃtica de reaÃÃo; velocidade de agitaÃÃo e meio reacional. ApÃs seleÃÃo desses parÃmetros, as reaÃÃes de biorreduÃÃo foram estendidas a outros derivados prÃ-quirais da acetofenona, onde foram observadas bioconversÃes com rendimentos e excessos enantiomÃricos (ee) que variaram de baixas a elevadas porcentagens. De modo geral, foram observadas influencias eletrÃnica e estÃrica devidas ao tipo e a posiÃÃo relativa dos diferentes substituintes nos compostos aromÃticos. No caso de substratos contendo dois grupos funcionais diferentes suscetÃveis de reduÃÃo, foi observada baixa quimiosseletividade. Foram investigados tambÃm outros compostos carbonilicos, como: cetonas alifÃticas e aromÃticas, aldeÃdos aromÃticos e nitrocompostos aromÃticos. Em adiÃÃo foi investigado a possibilidade de aÃÃo hidrolÃtica a partir de compostos pertencente Ãs funÃÃes Ãsteres, amidas e nitrilas. Os rendimentos das reaÃÃes foram calculados utilizando Cromatografia Gasosa acoplada à Espectrometria de Massas (CG-EM) e RessonÃncia MagnÃtica Nuclear de HidrogÃnio (RMN 1H). Os excessos enantiomÃricos (ee) foram determinados atravÃs de Cromatografia LÃquido de Alta EficiÃncia (CLAE) equipada com colunas quirais.
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O'Leary, Christine Marie. "Expression of the Ets family in the lens." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.78 Mb., 100 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/1428194.
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Tomlinson, Julie. "Calcium in relation to lens physiology and pathology." Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292537.
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Heistand, Mark Richard. "Biomechanics of the lens capsule." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2726.
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Knowledge of the mechanics of the lens capsule is crucial for improving cataract surgery as well as understanding better the physiological role of the lens capsule in the process of accommodation. Previous research on the mechanical properties of the lens capsule contains many gaps and contradictions due to experimental limitations and inappropriate assumptions. Thus, the goal of this work is to quantify fully the regional, multiaxial mechanical behavior of the lens capsule and to calculate the change in stress and strain fields as a result of cataract surgery.
Determining in situ the multiaxial mechanical behavior of the lens capsule required the design and construction of an experimental device capable of altering stresses in the capsule while measuring localized surface deformations. Tests performed on this device reveal that the meridional and circumferential strains align with the principal directions and are equivalent through most of the anterior lens capsule, except close to the equator where the meridional strain is greater. Furthermore, preconditioning effects were also found to be significant. Most importantly, however, these tests provide the data necessary for calculating material properties.
This experimental system is advantageous in that it allows reconstruction of 3D geometry of the lens capsule and thereby quantification of curvature changes, as well as measurement of surface deformations that result from various surgical interventions. For instance, a continuous circular capsulorhexis (CCC) is commonly used during cataract surgery to create a hole in the anterior lens capsule (typically with a diameter of 5 mm). After the introduction of a CCC, strain was found to redistribute evenly from the meridional direction (retractional strain) to the circumferential direction (extensional strain), where both directional components of strain reached magnitudes up to 20% near the edge of the CCC. Furthermore, the curvature was found to increase at the edge of the CCC and remain the same near the equator, indicating that the mere introduction of a hole in the lens capsule will alter the focal characteristics of the lens and must therefore be considered in the design of an accommodative intraocular lens.
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Banks, Eric A. "Connexin 45.6 in lens development : a dissertation /." San Antonio : UTHSC, 2007. http://proquest.umi.com/pqdweb?did=1400957401&sid=1&Fmt=2&clientId=70986&RQT=309&VName=PQD.
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Eom, Youngsub, Dongok Ryu, Dae Wook Kim, Seul Ki Yang, Jong Suk Song, Sug-Whan Kim, and Hyo Myung Kim. "Development of a program for toric intraocular lens calculation considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and effective lens position." Springer, 2016. http://hdl.handle.net/10150/621786.
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Background: To evaluate the toric intraocular lens (IOL) calculation considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and effective lens position (ELP). Methods Two thousand samples of corneal parameters with keratometric astigmatism >= 1.0 D were obtained using boot-strap methods. The probability distributions for incision-induced keratometric and posterior corneal astigmatisms, as well as ELP were estimated from the literature review. The predicted residual astigmatism error using method D with an IOL add power calculator (IAPC) was compared with those derived using methods A, B, and C through Monte-Carlo simulation. Method A considered the keratometric astigmatism and incision-induced keratometric astigmatism, method B considered posterior corneal astigmatism in addition to the A method, method C considered incision-induced posterior corneal astigmatism in addition to the B method, and method D considered ELP in addition to the C method. To verify the IAPC used in this study, the predicted toric IOL cylinder power and its axis using the IAPC were compared with ray-tracing simulation results. Results The median magnitude of the predicted residual astigmatism error using method D (0.25 diopters [D]) was smaller than that derived using methods A (0.42 D), B (0.38 D), and C (0.28 D) respectively. Linear regression analysis indicated that the predicted toric IOL cylinder power and its axis had excellent goodness-of-fit between the IAPC and ray-tracing simulation. Conclusions The IAPC is a simple but accurate method for predicting the toric IOL cylinder power and its axis considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and ELP.
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Andrulaitytė, Giedrė. "Įstrižojo astigmatizmo kompiuterinis modeliavimas sferiniuose ir asferiniuose lęšiuose." Bachelor's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140716_105157-99873.
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Bakalauro darbą „Įstrižojo astigmatizmo kompiuterinis modeliavimas sferiniuose ir asferiniuose lęšiuose“ sudaro įvadas, 5 dėstymo skyriai, išvados ir priedai. Darbe pateikiami 50 paveikslai ir 2 lentelės, cituojami 16 literatūros šaltinių. Darbo apimtis 66 lapai. Darbe apibendrinta literatūra apie lęšių aberacijas, jų įtaką regėjimo kokybei, bei minimalizavimą asferiniais lęšiais. Taip pat pateikiami matematiniai sferinių ir asferinių lęšių modeliai, bei įstrižojo astigmatizmo analizė šiuose lęšiuose. Įvade iškeliami darbo tikslai ir uždaviniai. Pirmajame skyriuje pateikta teorinė medžiaga apie lęšių aberacijas, antrajame – apie sferinius ir asferinius lęšius. Išanalizuoti galimi asferinių lęšių paviršiai ir jų pranašumas prieš sferinius paviršius. Trečiajame skyriuje pateikiamas matematinis spindulių eigos modelis sferiniame paviršiuje. Ketvirtajame – matematinis spindulių eigos modelis asferiniame paviršiuje. Penktajame skyriuje lyginami kompiuterinių modelių pagalba gauti įstrižojo astigmatizmo apibūdinti rezultatai, tangentinėmis paklaidomis.The bachelor’s thesis „The computer modeling of oblique astigmatism in spherical and aspherical lenses” consists of introduction, 5 chapters, conclusions and attachments. The thesis introduces 50 figures, 2 tables and refers to 16 literary sources. The volume of the work is 66 pages. The work summarizes the literature which describes the lens aberrations, its influence to quality of vision and reduction by using aspheric lenses. There is also included mathematical models of spherical and aspheric lenses, and analysis of oblique astigmatism in them. The introduction sets the aims and the goals of the study. The first chapter contains theoretic material about lens aberrations, the second – about spherical and aspheric lenses, the analysis about available surfaces of aspheric lenses and advantages of them. The third chapter contains mathematical model of light rays pathway in spherical lenses. The fourth chapter contains mathematical model of light rays pathway in aspheric lenses. The fifth chapter contains comparison of oblique astigmatism described as tangential errors in those two models.
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Wang, Kai. "Involvement of O-glcnacylation in lens development and cataract formation." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2010r/wang.pdf.
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Bassnett, S. "Ion activity and membrane function in the lens." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377710.
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Ferreira, Daniele Alves. "Reações biocatalíticas usando células íntegras de Lens culinaris (Lentilha)." reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/10915.
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FERREIRA, D. A. Reações biocatalíticas usando células íntegras de Lens culinaris (Lentilha). 2012. 144 f. Tese (Doutorado em Química) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012.Submitted by José Jairo Viana de Sousa (jairo@ufc.br) on 2014-10-17T19:36:21Z No. of bitstreams: 1 2012_tese_daferreira.pdf: 4506710 bytes, checksum: 94cfd04a00906636065e44839b576c29 (MD5)
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This paper describes the use of seeds of lentil (Lens culinaris) as intact plant system in biocatalytic reactions of reduction and hydrolysis. Initially, some plant sources were evaluated for their action in the biocatalytic reduction of aromatic ketone acetophenone. The plants that showed positive results in the reduction reaction underwent determination of their protein content by the methods of Lowry and Bradford. Lens culinaris was plant species revealed that most relevant biocatalytic activity, in agreement with their high protein content (1.33 mg / mL and 1.07 mg / mL according to Bradford and Lowry methods, respectively), and thus The plant was selected for further study. Subsequently, always using the model substrate acetophenone as the reaction parameters were optimized: concentration of biocatalyst; reaction kinetics; stirring speed the reaction medium. After selecting these parameters, the bioreduction reactions were extended to other derivatives of prochiral acetophenone, which were observed with bioconversions yields and enantiomeric excess (ee) ranging from low to high percentages. Generally, were observed steric and electronic influences due to the type and relative position of the various substituents on aromatic compounds. In the case of substrates containing two different functional groups susceptible to reduction, low chemoselectivity observed. Investigated also other carbonyl compounds such as aliphatic and aromatic ketones, aromatic aldehydes and aromatic nitro compounds. In addition investigated the possibility that hydrolytic action from compounds belonging functions esters, amides and nitriles. The yields of the reactions were calculated using Gas Chromatography coupled with Mass Spectrometry (GC-MS) and Nuclear Magnetic Resonance Hydrogen (1H NMR). The enantiomeric excess (ee) were determined by High Performance Liquid Chromatography (HPLC) equipped with chiral columns.
Este trabalho relata a utilização das sementes de lentilha (Lens culinaris) como sistema íntegro de planta em reações biocatalíticas de redução e hidrólise. Inicialmente, algumas fontes vegetais foram avaliadas quanto sua ação biocatalítica na redução da cetona aromática acetofenona. Os vegetais que revelaram resultados positivos na reação de redução foram submetidos à determinação do seu teor de proteínas através dos métodos de Lowry e Bradford. Lens culinaris foi à espécie vegetal que revelou atividade biocatalítica mais relevante, em acordo com seu alto teor de proteína (1,33 mg/mL e 1,07 mg/mL, segundo os métodos de Bradford e Lowry, respectivamente), e assim, foi o vegetal selecionado para estudos mais aprofundados. Posteriormente, utilizando sempre a acetofenona como substrato modelo foram otimizados os parâmetros reacionais: concentração do biocatalisador; cinética de reação; velocidade de agitação e meio reacional. Após seleção desses parâmetros, as reações de biorredução foram estendidas a outros derivados pró-quirais da acetofenona, onde foram observadas bioconversões com rendimentos e excessos enantioméricos (ee) que variaram de baixas a elevadas porcentagens. De modo geral, foram observadas influencias eletrônica e estérica devidas ao tipo e a posição relativa dos diferentes substituintes nos compostos aromáticos. No caso de substratos contendo dois grupos funcionais diferentes suscetíveis de redução, foi observada baixa quimiosseletividade. Foram investigados também outros compostos carbonilicos, como: cetonas alifáticas e aromáticas, aldeídos aromáticos e nitrocompostos aromáticos. Em adição foi investigado a possibilidade de ação hidrolítica a partir de compostos pertencente às funções ésteres, amidas e nitrilas. Os rendimentos das reações foram calculados utilizando Cromatografia Gasosa acoplada à Espectrometria de Massas (CG-EM) e Ressonância Magnética Nuclear de Hidrogênio (RMN 1H). Os excessos enantioméricos (ee) foram determinados através de Cromatografia Líquido de Alta Eficiência (CLAE) equipada com colunas quirais.
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Rogers, Adam. "Gravitational lens modeling with iterative source deconvolution and global optimization of lens density parameters." Journal of the Royal Astronomical Society of Canada, 2012. http://hdl.handle.net/1993/5283.
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Strong gravitational lensing produces multiple distorted images of a background source when it is closely aligned with a mass distribution along the line of sight. The lensed images provide constraints on the parameters of a model of the lens, and the images themselves can be inverted providing a model of the source. Both of these aspects of lensing are extremely valuable, as lensing depends on the total matter distribution, both luminous and dark. Furthermore, lensed sources are commonly located at cosmological distances and are magnified by the lensing effect. This provides a chance to image sources that would be unobservable when viewed with conventional optics.
The semilinear method expresses the source modeling step as a least-squares problem for a given set of lens model parameters. The blurring effect due to the point spread function of the instrument used to observe the lensed images is also taken into account. In general, regularization is needed to solve the source deconvolution problem. We use Krylov subspace methods to solve for the pixelated sources. These optimization techniques, such as the Conjugate Gradient method, provide natural regularizing effects from simple truncated iteration. Using these routines, we are able to avoid the explicit construction of the lens and blurring matrices and solve the least squares source optimization problem iteratively. We explore several regularization parameter selection methods commonly used in standard image deconvolution problems, which lead to previously derived expressions for the number of source degrees of freedom.
The parameters that describe the lens density distribution are found by global optimization methods including genetic algorithms and particle swarm optimizers. In general, global optimizers are useful in non-linear optimization problems such as lens modeling due to their parameter space mapping capabilities. However, these optimization methods require many function evaluations and iterative approaches to the least squares problem are beneficial due to the speed advantage that they offer. We apply our modeling techniques to a subset of gravitational lens systems from the Sloan Lens ACS (SLACS) survey, and are able to reliably recover the parameters of the lens mass distribution with both analytical and regularized pixelated sources.
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Sagawa, Atsushi. "New solution for well test analysis in reservoirs with permeability discontinuities." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/551.
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Mital, Rashmi. "Design and demonstration of a novel optical true time delay technique using polynomial cells based on white cells." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1111161542.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xiii, 195 p.; also includes graphics (some col.) Includes bibliographical references (p. 190-195). Available online via OhioLINK's ETD Center
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Fisher, Damien. "The influence of scleral lens parameters and fitting characteristics on corneal oedema under open and closed eye conditions." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/211357/1/Damien_Fisher_Thesis.pdf.
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Scleral lenses are large rigid contact lenses used to treat diseases that affect the front surface of the eye. This thesis examined how scleral lens fitting characteristics can be optimised to reduce corneal tissue swelling. The results provide clinical guidance for contact lens practitioners and patients worldwide.
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Gilligan, Therese M. "Behind the lens : sensorimotor and cognitive after-effects of prism adaptation." Thesis, Bangor University, 2017. https://research.bangor.ac.uk/portal/en/theses/behind-the-lens(fd8b122f-8110-4aa8-ab21-105d476fe0bd).html.
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Over a century of research into prism adaptation (PA) has provided many insights into general sensorimotor functions including plasticity and the role of prediction. More recently, the therapeutic value of PA for conditions relating to right hemisphere dysfunction such as hemispatial neglect, and to body schema related conditions such as complex region pain syndrome, have generated a wealth of new knowledge – and more questions (Chapter 1). This thesis examines a cross-section of PA effects: sensorimotor adaptation in healthy participants and cognitive after-effects in a neurological population as well as a group of participants with a virtual lesion. Chapter 2 reports that PA does not induce an after-effect shift in a visual straightahead judgment task, while it does induce after-effects in other tasks which are attributable to a change in state estimates of eye position in the orbit. The results suggest that PA prompts complex changes within ocular proprioception and indicate that the assumption of linear additivity of PA sensorimotor after-effects is a concept requiring re-examination. An increase in priming following both right-shifting and left-shifting PA in patients with a left hemisphere lesion provides a first demonstration of the rehabilitative potential of PA for left hemisphere dysfunctions. Intriguingly, this result also widens the possible candidate mechanisms through which PA facilitates cognitive after-effects (Chapter 3). Finally, this thesis explores the potential influence of the cerebellum in the cognitive after-effects of PA (Chapter 4). It reports, for the first time, that neurodisruption of the right cerebellar hemisphere increases and left cerebellar stimulation decreases word association priming. The results indicate that the two cerebellar hemispheres conjointly schedule the facilitation and inhibition of associative priming. Taken together, the novel findings reported here suggest that previous theoretical stand-points need to be revised and provide a new framework for understanding the relationship between sensorimotor adaptation, cerebellar function and hemispheric interactions in human cognition.