Search results for "structures"

Structure and optical properties of a monolayer single crystal of a cyanine dye

1992

Abstract Molecularly thin single crystals of a cyanine dye prepared by adsorption at a charged surfactant monolayer are studied by polarized optical spectroscopy and electron diffraction. Both techniques independently show a herringbone arrangement of the dye with the long axes of translationally inequivalent molecules forming an angle of 80°. The dye arranges in a primitive rectangular unit cell (a=21.2 A, b=6.14 A) adjacent to an epitaxially related hexagonal cell of the aliphatic tails of the surfactant.

The interplay between cooperativity and diversity in model threshold ensembles

2014

The interplay between cooperativity and diversity is crucial for biological ensembles because single molecule experiments show a significant degree of heterogeneity and also for artificial nanostructures because of the high individual variability characteristic of nanoscale units. We study the cross-effects between cooperativity and diversity in model threshold ensembles composed of individually different units that show a cooperative behaviour. The units are modelled as statistical distributions of parameters (the individual threshold potentials here) characterized by central and width distribution values. The simulations show that the interplay between cooperativity and diversity results …

Beals–Hecht syndrome and choroidal neovascularization

2010

Roberto Gallego-Pinazo1, Ruth López-Lizcano1, José María Millán2,3, J Fernando Arevalo5, J Luis Mullor6, Manuel Díaz-Llopis1,3,41Department of Ophthalmology, 2Department of Genetics, Unit of Experimental Opthalmology, Hospital Universitario La Fe, Valencia, Spain; 3Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain; 4Faculty of Medicine, University of Valencia, Valencia, Spain; 5Retina and Vitreous Service, Clínica Oftalmológica Centro Caracas, Caracas, Venezuela; 6Unit of Experimental Opthalmology, Fundación Parala Investigación del…

Acute endothelial failure after cosmetic iris implants (NewIris®)

2011

Maria Garcia-Pous1, Patricia Udaondo2, Salvador Garcia-Delpech2, David Salom1, Manuel Díaz-Llopis21Faculty of Medicine, University of Valencia, Valencia, Spain; 2Ophthalmology Department, Hospital Universitario La Fe, Valencia, SpainAbstract: We report a case of an acute endothelial failure after the implantation of a new cosmetic, colored, artificial iris diaphragm implant called NewIris®. A 21-year-old woman came to us complaining of progressive loss of vision and pain after NewIris lenses had been implanted. Decreased visual acuity, corneal edema, and increased intraocular pressure in both eyes appeared only 3 weeks after the surgery. The lenses were removed as soon as…

Visual fields in a chloroquine treatment

2014

María del Carmen García-Domene,1,2 María Amparo Díez-Ajenjo,1,3 María Dolores de Fez,4 María José Luque2 1Fisabio Oftalmología Médica, València, 2Departament d'Òptica, Facultat de Física, Universitat de València, Burjassot, 3Clínica Optométrica Fundación Lluís Alcanyís, Valencia, 4Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Alicante, SpainPurpose: In this study, we describe contrast sensitivity losses in the visual field of a …

2019

Abstract Frequency tagging has been widely used to study the role of visual selective attention. Presenting a visual stimulus flickering at a specific frequency generates so-called steady-state visually evoked responses. However, frequency tagging is mostly done at lower frequencies (

<title>Selective filters for improvement of color discrimination</title>

2003

Colored filters have been used as possible aids for perception in case of congenital color vision abnormalities. Higher stimulation for L cones in one eye (red filter) and for M cones (green) in other eye acts as a simple method to interfere in human color vision processing. Influence on subjective and objective vision performances as binocular functions, fusion, stereopsis and color vision has been tested. Special colored glasses have been created, taking into account each subjects refraction for distance and tested for the 5 months adaption time. No negative influence on binocular functions, no changes of heterophoria and lowering in fusion ability and stereopsis have been stated due to u…

Color induction via non-opponent lateral interactions in the human retina

1992

Retinal connections causing colors in Benham's top (pattern induced flicker colors, PIFCs) are investigated by psychophysical experiments. PIFCs are still seen when stimuli to different cones are demodulated selectively, indicating the involvement of non-opponent channels. PIFCs also occur on retinal areas next to those affected by modulated stimuli; further, both monochromat and dark-adapted trichromats perceive PIFCs which are achromatic. These additional findings point to horizontal cells as neuronal mediators of modulated excitation leading to PIFCs. The unspecifity of the postulated connection with respect to cone types agrees with anatomic findings of Boycott, B. B., Hopkins, J. M. an…

Motion detection in goldfish investigated with the optomotor response is “color blind”

1996

AbstractThe action spectrum of the optomotor response in goldfish was measured to investigate which of the four cone types involved in color vision contributes to motion detection. In the dark-adapted state, the action spectrum showed a single maximum in the range of 500–520 nm, and resembled the rod spectral sensitivity function. Surprisingly, the action spectrum measured in the light-adapted state also revealed a single maximum only, located in the long wavelength range between 620 and 660 nm. A comparison with spectral sensitivity functions of the four cone types suggests that motion detection is dominated by the L-cone type. Using a two colored, “red-green” cylinder illuminated with two…

Visual fields in a chloroquine treatment

2014

Purpose: In this study, we describe contrast sensitivity losses in the visual field of a patient affected by chloroquine toxicity, measured with stimuli favoring different visual mechanisms. We have compared these results with those of other, usual clinical tests. Methods: The vision of a patient who underwent ten years of chloroquine treatment was analyzed by a battery of clinical tests: visual acuity (VA), Amsler’s grid, Farnsworth–Munsell 100-hue test, spectral domain optical coherence tomography, multifocal electroretinogram (ERG), white-on-white and red-on-white Humphrey perimetries, chromatic and achromatic contrast sensitivity perimetry tests, and fluorescein angiography. Measurement…