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PubMed1965

COLOR AND STREPTOMYCETES. REPORT OF AN INTERNATIONAL WORKSHOP ON DETERMINATION OF COLOR OF STREPTOMYCETES.

A report summarizing the results of an international workshop on determination of color of streptomycetes is presented. The results suggest that the color systems which seem most practically appealing and effective to specialists on actinomycetes are those embracing a limited number of color names and groups. The broad groupings allow placement of isolates into reasonably well-defined categories based on color of aerial mycelium. Attempts to expand such systems (more color groups) lead to difficulties. It is common knowledge that many, if not all, of the individual groups would in these broad systems contain strains that differ in many other respects, e.g., spore-wall ornamentation, color of vegetative (substratal) mycelium, morphology of chains of spores, and numerous physiological criteria. Also, cultures of intermediate color can be found, which makes placement difficult. As it now stands, color as a criterion for characterization of streptomycetes and streptoverticillia is in questionable status. Although much useful color information can be obtained by an individual, the application of this information to that in the literature or its use in communication with other individuals leaves much to be desired. More objective methods of color determination are needed. At present, the most effective method that could be used internationally is the color-wheel system of Tresner and Backus. Furthermore, the significance of color in speciation of these organisms is an open question. Obviously, more critical work on the color problem is needed.

Classification↗
PubMedDate not supplied

Color naming and categorization in inherited color vision deficiencies.

Dichromatic subjects can name colors accurately, even though they cannot discriminate among red-green hues (Jameson & Hurvich, 1978). This result is attributed to a normative language system that dichromatic observers developed by learning subtle visual cues to compensate for their impoverished color system. The present study used multidimensional scaling techniques to compare color categorization spaces of color-vision deficient (CVD) subjects to those of normal trichromat (NT) subjects, and consensus analysis estimated the normative effect of language on categorization. Subjects sorted 140 Munsell color samples in three different ways: a free sorting task (unlimited number of categories), a constrained sorting task (number of categories limited to eight), and a constrained naming task (limited to eight basic color terms). CVD color categories were comparable to those of NT subjects. For both CVD and NT subjects, a common color categorization space derived from the three tasks was well described by a three-dimensional model, with the first two dimensions corresponding to reddish-greenish and yellowish-bluish axes. However, the third axis, which was associated with an achromatic dimension in NTs, was not identified in the CVD model. Individual differences multidimensional scaling failed to reveal group differences in the sorting tasks. In contrast, the personal color naming spaces of CVD subjects exhibited a relative compression of the yellowish-bluish dimension that is inconsistent with the typical deutan-type color spaces derived from more direct measures of perceptual color judgments. As expected, the highest consensus among CVDs (77%) and NTs (82%) occurred in the naming task. The categorization behaviors studied in this experiment seemed to rely more on learning factors, and may reveal little about CVD perceptual representation of colors.

Adult↗
PubMed2005

Experimental design for three-color and four-color gene expression microarrays.

MOTIVATION: Three-color microarrays, compared with two-color microarrays, can increase design efficiency and power to detect differential expression without additional samples and arrays. Furthermore, three-color microarray technology is currently available at a reasonable cost. Despite the potential advantages, clear guidelines for designing and analyzing three-color experiments do not exist. RESULTS: We propose a three- and a four-color cyclic design (loop) and a complementary graphical representation to help design experiments that are balanced, efficient and robust to hybridization failures. In theory, three-color loop designs are more efficient than two-color loop designs. Experiments using both two- and three-color platforms were performed in parallel and their outputs were analyzed using linear mixed model analysis in R/MAANOVA. These results demonstrate that three-color experiments using the same number of samples (and fewer arrays) will perform as efficiently as two-color experiments. The improved efficiency of the design is somewhat offset by a reduced dynamic range and increased variability in the three-color experimental system. This result suggests that, with minor technological improvements, three-color microarrays using loop designs could detect differential expression more efficiently than two-color loop designs. AVAILABILITY: http://www.jax.org/staff/churchill/labsite/software SUPPLEMENTARY INFORMATION: Multicolor cyclic design construction methods and examples along with additional results of the experiment are provided at http://www.jax.org/staff/churchill/labsite/pubs/yong.

Algorithms↗
PubMed1987

The color accuracy of the Kubelka-Munk theory for various colorants in maxillofacial prosthetic material.

The reflectance model developed by Kubelka and Munk was evaluated for agreement in color prediction of thick pigmented samples and for linearity of optical absorption and scattering coefficients with concentration of colorant in maxillofacial elastomer. The colorants tested were generic opacifiers, dry mineral earth pigments, and fibrous colorants. Significant linear relationships were commonly found between the optical coefficients and the concentration of the colorants. These relationships indicated occasional optical interaction between the colorants and the elastomer. Color differences between theoretical and observed colors of the thick samples averaged 2.96, 3.47, and 1.60 for the opacifiers, mineral earth pigments, and fibrous colorants, respectively, when measured using the CIELAB uniform-color space. The agreement between theoretical and observed colors was significantly closer for the fibrous colorants than for the dry mineral earth pigments of the same labeled color.

Color↗
PubMedDate not supplied

The color of night: Surface color perception under dim illuminations.

Several studies document rudimentary color vision under dim illumination. Here, hue perceptions of paper color samples were determined for a wide range of light levels, including very low light levels where rods alone mediate vision. The appearances of 24 paper color samples from the OSA Uniform Color Scales were gauged under successively dimmer illuminations from 10-0.0003 Lux. Triads of samples were chosen representing each of eight basic color categories; red, pink, orange, yellow, green, blue, purple, and gray. Samples within each triad varied in lightness. Observers sorted samples into groups that they could categorize with specific color names. Above 0.32 Lux, observers sorted the samples into the originally chosen color groups with few exceptions. For 0.1-0.01 Lux, the red and orange samples were usually correctly identified as either red or orange. The remaining samples tended to be grouped into two categories, associated with the scotopic sample reflectance. The lowest reflectance samples were below threshold and were named black. The higher reflectance group was named predominately as green or blue-green (three observers; the fourth observer used blue or achromatic). At the three dimmest levels (< or = 0.0032 Lux) there continued to be conspicuous color percepts. Color categories were reliably assigned based on relative sample scotopic lightness. Of the samples above threshold, those with lower reflectance were classified as red or orange (all observers) and the higher reflectance samples as green or blue-green (three observers) or achromatic or blue (the fourth observer). Rods and L-cones presumably mediated color percepts at the intermediate light levels used in the study. At the three lowest light levels there were distinct color appearances mediated exclusively by rods. We speculate that at these light levels the visual system estimates probable colors based on prior natural experience.

Color↗
PubMed1998

Complete sparing of high-contrast color input to motion perception in cortical color blindness.

It is widely held that color and motion are processed by separate parallel pathways in the visual system, but this view is difficult to reconcile with the fact that motion can be detected in equiluminant stimuli that are defined by color alone. To examine the relationship between color and motion, we tested three patients who had lost their color vision following cortical damage (central achromatopsia). Despite their profound loss in the subjective experience of color and their inability to detect the motion of faint colors, all three subjects showed surprisingly strong responses to high-contrast, moving color stimuli--equal in all respects to the performance of subjects with normal color vision. The pathway from opponent-color detectors in the retina to the motion analysis areas must therefore be independent of the damaged color centers in the occipitotemporal area. It is probably also independent of the motion analysis area MT/V5, because the contribution of color to motion detection in these patients is much stronger than the color response of monkey area MT.

Adult↗
PubMedDate not supplied

[Positive influence of color experience on result of color-arrangement-test Roth 28-hue (E) desaturated - a clinical study on 44 patients].

BACKGROUND: The color arrangement test can be applied for early diagnosis of diabetic retinopathy, even small confusion of colors influence clinical diagnosis. It is therefore necessary to be aware of influential factors. METHODS: Forty-four patients with color-experience (VW-Werk Wolfsburg) were included and devided in two groups: group 1: non-smokers without ophthalmological and systemic diseases (n = 27, 42+/-9 years), group 2: smokers without ophthalmological and systemic diseases (n = 17; 43+/-8 years). The control group 3 (n = 30; 42+/-4 years) included non-smokers and the control group 4 (n = 10; 42+/-8 years) smokers, both groups without color-experience, ophthalmological and systemic diseases. Besides the ophthalmological examinations (visual acuity, refraction, intraocular pressure, slit lamp and fundus examination) the color-vision was tested by the color-arrangement-test Roth 28-hue (E) desaturated monocularly under standard conditions: The background used was black cardboard, illuminated by two Osram fluorescent lamps (L36W/12LDL Daylight) providing 2000 lux at the test table. RESULTS: Ophthalmological examination in all subjects was without pathological findings. The mean error score in the non-smokers with color-experience (median+/-mean absolute deviation: 48+/-47) was lower than in the non-smokers without color experience (72+/-45; Mann-Withney-U-Test: p = 0.02). The mean error score in the smokers with color-experience (60+/-60) was lower than in the smokers without color-experience (156+/-65; p = 0.0014). No statistically significant difference was found between the measurements of the right and left eye (Wilcoxon-Test: group 1: p = 0.89; group 2: p = 0.9; group 3: p = 0.77; group 4: p = 0.87). CONCLUSION: Color experience improves the results in color-arrangement-tests like the Roth 28-hue (E) desaturated and should be considered in quantitative evaluation.

Adult↗
PubMed1990

Study of estimation of color recognition on the dentist. On the ability of subjects to discriminate color in terms of hue, value and chroma.

The tooth crown color space model was manufactured and the improvement of the color representation and communication on the dental clinic have been trying. The study of color discrimination by dentist and student viewing with the use of tooth crown color chips reported here in basic knowledge on the color sensitivity of human eye. The test card were 55 x 90 mm in size and the color chip, 5 x 10 mm. The paired color chips were placed on the test card to have a 2 mm distance between them. Color difference of two tooth crown color chips on the test cards was 3.5 (delta E*ab), the combination of hue, value and chroma was constant of all cards. The subjects were 22 people, 6 dentists and 16 dental school students with normal color sensibility. In proportion of method of comparison for surface color (JIS Z 8723), the subject observed the test card which were different of hue, value and chroma on the their naked-eye, were investigated to evaluate their judgement of the test cards. The following results were obtained. The standard of judgment for the color discrimination was made firstly in terms of hue, secondly in terms of value, and thirdly in terms of chroma.

Adult↗
PubMed1996

Performance of color-dependent air traffic control tasks as a function of color vision deficiency.

BACKGROUND: This experiment was conducted to validate the requirement for normal color vision in Air Traffic Control Specialist (ATCS) personnel who work at en route center, terminal, and Flight Service Station (FSS) facilities. METHODS: A data base was developed involving 121 individuals with normal color vision, 31 simple and 44 extreme anomalous trichromats, and 48 dichromats; both protans and deutans were included. The performance of subjects with normal color vision was compared with the performance of individuals with various classifications of color vision deficiencies on a battery of color-dependent ATCS tasks. Simulations of the ATC color tasks concerned color coding in flight progress strips (at en route centers), aircraft lights and Aviation Signal Light indicator (in tower operations), and color weather radar (at FSS's). RESULTS: Errors were rare among normal trichromats. Mean errors were significantly higher at every level (degree) of color vision deficiency. Approximately 6% of color deficient subjects were able to perform ATC color tasks without error. The 6% were all from the simple anomalous trichromat category; all extreme anomalous trichromats and dichromats were prone to error on ATC tasks. CONCLUSIONS: We conclude that these findings provide support for the requirement of normal color vision in the initial medical screening of ATCS personnel.

Accidents, Aviation↗
PubMed1990

[Early diagnosis of congenital disorders of color vision with the Velhagen "Pflügerhaken Color Charts for evaluating color perception" in 3,375 preschool children].

In three series of examinations, 3375 male preschool-age children and 93 adult normal trichromates were tested using the Velhagen Pflügerhaken charts. The authors recommend modifying the evaluation of the results slightly by introducing a "doubteful" category for children who make one mistake or who show hesitation and lack of assurance in interpreting the charts. Using this modified form of assessment, diagnoses of "probably achromatopic" and "doubtful" were made in 7.16% and 2.13% respectively of 1689 preschool-age boys. The failure rate during the test and the duration of the examination were age-dependent, and declined with increasing age from 4.15% to 0.45% and from 1.18 min to 0.59 min, respectively. Most mistakes were made with charts nos. 9, 3, and 5. The results of tests with Pflügerhaken charts are fully comparable with those of other internationally used tests for adults. They can be recommended for screening preschool-age children.

Adult↗