Search results for "C35"
showing 10 items of 71 documents
Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy
2020
Plasmonic nanostructures are widely utilized in surface-enhanced Raman spectroscopy (SERS) from ultraviolet to near-infrared applications. Periodic nanoplasmonic systems such as plasmonic gratings are of great interest as SERS-active substrates due to their strong polarization dependence and ease of fabrication. In this work, we modelled a silver grating that manifests a subradiant plasmonic resonance as a dip in its reflectivity with significant near-field enhancement only for transverse-magnetic (TM) polarization of light. We investigated the role of its fill factor, commonly defined as a ratio between the width of the grating groove and the grating period, on the SERS enhancement. We des…
Retinal Straylight Before and After Penetrating Keratoplasty in an Eye with a Post-Herpetic Corneal Scar
2008
Objetivo: Estudio in vivo de la luz dispersa que alcanza la retina en un paciente antes y despues de someterse a una queratoplastia penetrante (o sus siglas en ingles, PKP). Metodos: En un paciente varon de 65 anos con una ulcera corneal herpetica se midio la proporcion de luz dispersa que alcanza la retina tanto antes como despues de una PKP, utilizando para ello un metodo psicometrico denominado "de comparacion por compensacion" («Compensation comparison method», C-Quant straylightmeter, Oculus GmbH, Alemania). Resultados: La cantidad de luz dispersa que alcanza la retina medida antes de la cirugia fue elevada en comparacion con los valores obtenidos en estudios previos en sujetos normale…
Seat Competitiveness and Redistricting: Evidence from Voting on Municipal Mergers
2013
We analyze how (anticipated) changes in the competitiveness of the seats of municipal councilors affect their voting behavior over municipal mergers. The competitiveness of the seats changes because the merger changes the composition of political competitors and the number of available seats in the next election. We use this variation for identification and find that the smaller the increase in the competitiveness of a councilor's seat, the more likely he is to vote for the merger. These effects are not related to the behavioral responses of the voters, but arise from the councilors’ desire to avoid electoral competition.
Variations of OCT measurements corrected for the magnification effect according to axial length and refractive error in children
2018
Purpose: The aim of this paper was to examine the distribution of macular, retinal nerve fiber layer (RNFL) thickness and optic disc parameters of myopic and hyperopic eyes in comparison with emmetropic control eyes and to investigate their variation according to axial length (AL) and spherical equivalent (SE) in healthy children. Methods: This study included 293 pairs of eyes of 293 children (145 boys and 148 girls), ranging in age from 6 to 17 years. Subjects were divided according to SE in control (emmetropia, 99 children), myopia (100 children) and hyperopia (94 children) groups and according to axial AL in 68 short ([Formula: see text]22.00[Formula: see text]mm, 68), medium (from [For…
Biometric characterization of the anterior segment in a Sahrawi pediatric population
2013
Purpose: To examine the biometric characteristics of the anterior segment in a group of Sahrawi children. Methods: A total of 66 children (33 male and 33 female, aged between 8 and 13 years) participated in this prospective, observational study. The non-invasive Pentacam Scheimpflug imaging device was used to measure corneal thickness (CT) (at the thinnest corneal point), mean anterior (Km Ant) and posterior (Km Post) corneal radii, corneal volume (CVol), anterior chamber depth (ACD) and anterior chamber volume (ACVol). The contribution of age and gender to the various parameters was investigated. Results: CT values of the present group of Sahrawi children were 521.70 ± 3.92 m. Boys had thi…
Interocular differences in visual quality due to ocular aberrations and scattering in a patient with post-traumatic anisocoria: A case report
2012
AbstractA 41-year-old patient with visual disturbances after an ocular trauma in right eye three years before was carefully analyzed and discussed. No corneal or intraocular sequelae were present. Only a significant anisocoria could be observed. Right eye (RE) achieved a best spectacle-corrected visual acuity (BSCVA) of 0.05 LogMAR with a refraction of +0.50 sphere and −1.25 cylinder. Left eye (LE) achieved a BSCVA of 0.0 LogMAR with a refraction of +0.75 sphere and −1.00 cylinder. In photopic conditions pupil diameter was 4.96mm for RE and 3.02mm for LE whereas in scotopic conditions, these values were 7.45mm and 6.71mm, respectively. More significant levels of higher-order corneal and ocu…
Preliminary in vivo positional analysis of a posterior chamber phakic intraocular lens by optical coherence tomography and its correlation with clini…
2012
Purpose: To analyze by spectral-domain optical coherence tomography the anatomical relationship of a specific type of posterior chamber phakic intraocular lens (pIOL) implanted in cases of high to moderate myopia with the adjacent intraocular structures and to correlate it with clinical outcomes. Methods: Prospective observational case series including 18 eyes with high to moderate myopia (spherical equivalent between −5.88 and −15.75 D) of 9 patients (age range, 29–49 years) undergoing bilateral Phakic Refractive Lens (PRL, Zeiss) implantation. Postoperative visual acuity, refraction, contrast sensitivity (CS), and ocular higher order aberrations (HOA) were evaluated. Furthermore, the in v…
Anterior chamber depth measurement in teenagers. Comparison of two techniques
2013
Purpose: The aim of this study is to determine the anterior chamber depth (ACD) in teenagers using two different devices: partial coherence interferometry IOLMaster (Carl Zeiss Meditec) and anterior segment optical coherence tomography (Visante TM OCT, Carl Zeiss Meditec) and to evaluate the degree of agreement between ACD measurements carried out by both instruments. Methods: In this prospective study 68 eyes of 34 emmetropic Caucasic patients (18 girls and 16 boys) were analysed. ACD was measured from the anterior corneal surface to anterior surface of the crystalline lens. For each age the ACD size was calculated and the difference between IOLMaster and Visante-OCT measurements was analy…
Visual Performance after AcrySof ReSTOR Aspheric Intraocular Lens Implantation
2008
Purpose: To evaluate distance, intermediate and near visual performance in patients who had undergone implantation of the multifocal aspheric AcrySof ReSTOR intraocular lens (IOL). Methods: Binocular best distance corrected visual acuity (BCVA) at high and low contrast [4 m], best distance corrected near visual acuity (BCNVA) [40 cm], intermediate visual acuity [80 and 60 cm], and distance contrast sensitivity (CS) under photopic [85 cd/m2] and mesopic [3 cd/m2] conditions, were measured in 36 eyes that underwent implantation of the AcrySof ReSTOR Aspheric IOL (SN6AD3). Results: At the 3-month postoperative visit, binocular BCVA was -0.058±0.091, 0.200±0.079, and 0.258±0.071 logMAR, for 100…
Extremal Irregular Digraphs
2018
A digraph is called irregular if its distinct vertices have distinct degree pairs. An irregular digraph is called minimal (maximal) if the removal of any arc (addition of any new arc) results in a non-irregular digraph. It is easily seen that the minimum sizes among irregular n-vertex whether digraphs or oriented graphs are the same and are asymptotic to (√2/3) n3/2; maximum sizes, however, are asymptotic to n2 and n2/2, respectively. Let s stand for the sum of initial positive integers, s = 1, 3, 6, . . . . An oriented graph Hs and a digraph Fs, both large (in terms of the size), minimal irregular, and on any such s vertices, s ≥ 21, are constructed in [Large minimal irregular digraphs, Op…