María Isabel Suero

A new colour vision test in a PC-based screening system

Abstract The most commonly used method to examine the ability of the visual system to discriminate colours and detect colour vision deficiencies is based on pseudoisochromatic plates, such as the Ishihara plates. We describe a computer-based method to determine red–green colour deficiencies based on an anomaloscope simulator, which gave good results in a study of red–green discrimination is studied. It was shown experimentally that this computer-based method discriminates between subjects with colour deficiencies and subjects without colour deficiencies.

Characterization of dichromat and trichromat observers using a PC-based anomaloscope

Abstract A system is presented for characterizing anomalous colour observers according to the type of colour vision deficiency that they suffer. The system is based on the simulation of a Pickford–Nicholson type anomaloscope using a cathode ray tube and a personal computer. By means of this method, it has been possible to determine the type of deficiency of the red–green chromatic channel presented by various anomalous observers.

Infrared and Raman Spectra of Tribromoacetic Acid and Its Potassic Salt

Abstract Infrared and Raman spectra of tribromoacetic acid and its potassic salt have been recorded as solid and aqueous solutions. A general assignment of the vibrational spectrum of the acid has been proposed on the basis of a symmetry of centrosymmetric dimers. The results agree with those for other halogen derivatives of acetic acid.

Influence of the correlated color temperature of a light source on the color discrimination capacity of the observer.

It is well known that there are different preferences in correlated color temperature of light sources for daily living activities or for viewing artistic paintings. There are also data relating the capacity of observers to make judgments on color differences with the spectral power distribution of the light source used. The present work describes a visual color discrimination experiment whose results confirm the existence of a relationship between the correlated color temperature of a light source and the color discrimination capacities of the observers.

Vibrational Spectra of α-Pyrazinamide and 15N-α-Pyrazinamide

Abstract α-Pyrazinamide and its α-Pyrazinamide-d2 as well as the 15N-isotopic derivative were synthesized with an isotopic content of 99.4% and their Raman and infrared spectra were recorded and assigned on the basis of isotopic shifts.

Optimization of the correlated color temperature of a light source for a better color discrimination

In a previous work [J. Opt. Soc. Am. A29, A209 (2012)], we presented a visual color discrimination experiment whose results established the existence of a relationship between the correlated color temperature (CCT) of a light source and the color discrimination capacities of the observers. The results indicated the existence of a statistically significant difference in the color discrimination of unequal sample pairs when using light sources of different color temperatures, with the discrimination capacity being greater the higher the light sources color temperature. That previous work employed an RGBA-LED light source configured with three color temperatures: 2800, 5000, and 6500 K. In order to go a further step in this line, this work expanded the range of color temperatures up to 9700 K. The results showed that there is an optimum CCT of around 5000 K at which observers were found to have a greater color discrimination capability.

Converting a fluorescence spectrophotometer into a three-channel colorimeter for color vision research

An old fluorescence spectrophotometer was recycled to make a three-channel colorimeter. The various modifications involved in its design and implementation are described. An optical system was added that allows the fusion of two visual stimuli coming from the two monochromators of the spectrofluorimeter. Each of these stimuli has a wavelength and bandwidth control, and a third visual stimulus may be taken from a monochromator, a cathode ray tube, a thin film transistor screen, or any other light source. This freedom in the choice of source of the third chromatic channel, together with the characteristics of the visual stimuli from the spectrofluorimeter, give this design a great versatility in its application to novel visual experiments on color vision.

Infrared and Raman spectra of pyrazine-2,3-dicarboxylic acid and its dipotassic salt

Abstract Infrared spectra of pyrazine-2,3-dicarboxylic acid normal and with both acid groups deuterated, as well as its dipotassic salt haven been recorded as solid and aqueous solutions. Raman spectra with polarization measurements have been recorded and investigated for the first time. A general assignments of the vibrational spectrum has been proposed on the basic of a C2 symmetry.

Chromatic characterization of a three-channel colorimeter using back-propagation neural networks

This work describes a method for the chromatic characterization of a three-channel colorimeter of recent design and construction dedicated to color vision research. The colorimeter consists of two fixed monochromators and a third monochromator interchangeable with a cathode ray tube or any other external light source. Back-propagation neural networks were used for the chromatic characterization to establish the relationship between each monochromator’s input parameters and the tristimulus values of each chromatic stimulus generated. The results showed the effectiveness of this type of neural-network-based system for the chromatic characterization of the stimuli produced by any monochromator.

Misconceptions persistence on the electric circuits of direct current

In this work we seek to check that the misconceptions that the students possess on the electric circuits of direct current they are commons to students of different ages and they are so strongly ingrained that neither the instruction during many years allows to modify them.