Search results for "Eye"
showing 10 items of 2511 documents
Conservation of optical purity of amino acids: a principal problem in biochemical and proto-biochemical systems.
1981
Dor L-amino acids, regardless of their state (peptide-bound or free, in the solid state or in aqueous solution), tend to racemize. In a living cell this racemization is usually compensated by specific degradation and replacement of the unwanted polypeptides that contain the wrong enantiomers. But a few long-lived proteins that are synthesized at or near birth are never replaced. Well investigated is the racemization of L-aspartic acid at a rate of 0.1 to 1.14 per cent per year in proteins from lenses and dentine. Increased racemization of eye lens proteins has been related to a form of human eye disease known as brunescent cataracts. Also quite well investigated is the racemization of amino…
An approach to the measurement of the nonlinear refractive index of very short lengths of optical fibers
2018
A method for the measurement of the nonlinear-refractive index coefficient in single-mode optical fibers is presented. It takes advantage of the high sensitivity of the acousto-optic interaction effect in optical fibers to the fiber properties. Direct measurement of the nonlinear-refractive index change resulting from cross-phase modulation between a probe and a pump signal is obtained from the fiber's acousto-optic interaction performance. It is a non-interferometric method in which a very short length of fiber (<0.25 m) is required.
Optic fibre as a transducer of tendomuscular forces
1996
Direct in vivo tendon force measurements open up new possibilities for understanding of muscle-tendon loads during natural locomotion. The present report presents a new optic fibre method for such applications. The method is based on light intensity modulation by mechanical modification of the geometric properties of the optic fibre. A special optic fibre with a plastic covering buffer and with a total diameter of either 265 microns or 500 microns was carefully prepared at both ends for receiving and transmitting light. The fibre was inserted through the rabbit common calcaneal tendon with a 20 gauge needle. By removing the needle the optic fibre remained in situ. Static loading demonstrate…
<title>Study of color centers in optical fibers to be used for ITER plasma diagnostics</title>
2007
ABSTRACT The paper presents a comparative study, by off-line measurements of the irradiation induced optical attenuation in several large diameter (600 µm) optical fibers subjected to gamma-rays and neutron irradiation. The optical fiber samples fall into two categories: optical fibers with an enhanced UV transmission (high OH content core) and solarization resistant optical fibers. The irradiation conditions were as follows: a) gamma irradiation at a 60 Co source, with a dose rate of 0.33 kGy/h +/- 5%, up to the maximum total irradiation dose of 313 kGy; b) neutron irradiation (mean energy 5.2 MeV) using a deuteron beam (13 MeV) and a thick beryllium target, for a total fluence of 6x10 12 …
Intraspecific Differences in Spectral Reflectance Curves as Indicators of Reduced Vitality in High-Arctic Plants
2017
Remote sensing is a suitable candidate for monitoring rapid changes in Polar regions, offering high-resolution spectral, spatial and radiometric data. This paper focuses on the spectral properties of dominant plant species acquired during the first week of August 2015. Twenty-eight plots were selected, which could easily be identified in the field as well as on RapidEye satellite imagery. Spectral measurements of individual species were acquired, and heavy metal contamination stress factors were measured contemporaneously. As a result, a unique spectral library of dominant plant species, heavy metal concentrations and damage ratios were achieved with an indication that species-specific chan…
Optical Quality Comparison of Conventional and Hole-Visian Implantable Collamer Lens at Different Degrees of Decentering
2012
To compare the optical quality of implantable Collamer lens (ICL) with and without central hole (Hole ICL and conventional ICL) at different degrees of decentering.Experimental laboratory investigation.Wavefront aberrations of the -3, -6, and -12 diopter (D) V4b and -3, -6, and -12 D V4c ICLs were measured in 3 conditions-centered and decentered 0.3 and 0.6 mm-at 3-mm and 4.5-mm pupils. The root mean square of total higher order aberrations, trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, point spread function and simulated retinal images of ICLs were calculated from the wavefront aberrations for each ICL and all conditions of decenteri…
Correlation between optics quality of multifocal intraocular lenses and visual acuity
2009
Purpose To study the relationship between the optics quality of multifocal intraocular lenses (IOLs) and distance-corrected near, intermediate, and distance visual acuity to determine the degree to which optics quality must change to produce a significant difference in visual acuity. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Methods Monocular distance-corrected visual acuity (decimal and logMAR) was measured at 4 m, 70 cm, and 30 cm under photopic and mesopic conditions in eyes with 1 of 3 multifocal IOL models. Visual acuity versus the “average modulation” of the IOL was assessed. Results The pupil diameter and patient age were similar between the 3 IOL groups (20 …
Can ‘Fellow of the European Board of Ophthalmology Subspecialty Diploma in Glaucoma,’ a subspecialty examination on glaucoma induce the qualification…
2016
From 2015, the examination of Fellow of the European Board of Ophthalmology Subspecialty Diploma in Glaucoma (FEBOS-Glaucoma) was launched by the European Board of Ophthalmology (EBO) in cooperation with the European Glaucoma Society (EGS). This opinion aims at disclosing the background of the examination, prerequisite to the examination, and the value of the FEBOS-Glaucoma diploma.
285 DOWNREGULATION OF ORGANIC CATION TRANSPORTERS OCT1 (SLC22A1) AND OCT3 (SLC22A3) IN HUMAN HEPATOCELLULAR CARCINOMA AND THEIR PROGNOSTIC SIGNIFICAN…
2012
Background Organic cation transporters (OCT) are responsible for the uptake and intracellular inactivation of a broad spectrum of endogenous substrates and detoxification of xenobiotics and chemotherapeutics. The transporters became pharmaceutically interesting, because OCTs are determinants of the cytotoxicity of platin derivates and the transport activity has been shown to correlate with the sensitivity of tumors towards tyrosine kinase inhibitors. No data exist about the relevance of OCTs in hepatocellular carcinoma (HCC).
Human brain organoids assemble functionally integrated bilateral optic vesicles
2021
During embryogenesis, optic vesicles develop from the diencephalon via a multistep process of organogenesis. Using induced pluripotent stem cell (iPSC)-derived human brain organoids, we attempted to simplify the complexities and demonstrate formation of forebrain-associated bilateral optic vesicles, cellular diversity, and functionality. Around day 30, brain organoids attempt to assemble optic vesicles, which develop progressively as visible structures within 60 days. These optic vesicle-containing brain organoids (OVB-organoids) constitute a developing optic vesicle's cellular components, including primitive corneal epithelial and lens-like cells, retinal pigment epithelia, retinal progeni…