Color Defects Research Articles

Multidimensional luminescence microscope for imaging defect colour centres in diamond

We report a multidimensional luminescence microscope providing hyperspectral imaging and time-resolved (luminescence lifetime) imaging for the study of luminescent diamond defects. The instrument includes crossed-polariser white light transmission microscopy to reveal any birefringence that would indicate strain in the diamond lattice. We demonstrate the application of this new instrument to detect defects in natural and synthetic diamonds including N3, nitrogen and silicon vacancies. Hyperspectral imaging provides contrast that is not apparent in conventional intensity images and the luminescence lifetime provides further contrast.

Incidence of dyschromatopsy in glaucoma.

As proven in studies dating back to the eighteenth century, color vision changes may occur early in the course of glaucoma. Our aim was to reevaluate the incidence of acquired color vision deficiency in glaucoma patients of the University hospital Zürich by using the Panel D-15 test. Inclusion criteria of the study involved a diagnosis of glaucoma, age equal or greater than 18years with no upper limit and a best-corrected visual acuity (BCVA) smaller than ≤ 0.7 logMAR. All volunteers were tested twice monocularly for color vision with (1) the Ishihara color plate test and (2) the Farnsworth and Lanthony Panel D-15 test by one examiner (L.B.). Using the Moment of Inertia Method of Vingrys and King-Smith (Investig Ophthalmol Vis Sci 29(1):50-63, 1988), we measured the color defect type (blue-yellow, red-green or non-selective). One hundred and fifty-one eyes of 87 glaucoma patients were included in this study. Nine eyes showed a deficient result in the Ishihara test, which proves a congenital red-green weakness. Fifty-one (33.8%) eyes showed color vision anomalies in the desaturated test and 24 (15.9%) eyes in the saturated Panel D-15 test. A total of 25.2% and 8.6% of eyes in the desaturated and saturated test were diffuse dyschromatopsia, respectively. The second most prevalent deficiencies were blue-yellow defects with 4.0% and 4.6% of saturated and desaturated results. Just the covariate visual acuity had a significant influence on the Panel D-15 result, whereas other variables like age, sex or intraocular pressure did not show any impact. This study ascertains that the long-known theory of color vision defects in patients with glaucoma is also relevant in our sample of 151 eyes, providing continuity to claims firstly reported many years ago. Despite our results highlighting more diffuse dyschromatopsia than other similar experiments, we have also proven that the tritanomalous defects occur more frequently than other color defects.

Arabidopsis DXO1 possesses deNADding and exonuclease activities and its mutation affects defense-related and photosynthetic gene expression.

RNA capping and decapping tightly coordinate with transcription, translation, and RNA decay to regulate gene expression. Proteins in the DXO/Rai1 family have been implicated in mRNA decapping and decay, and mammalian DXO was recently found to also function as a decapping enzyme for NAD+ -capped RNAs (NAD-RNA). The Arabidopsis genome contains a single gene encoding a DXO/Rai1 protein, AtDXO1. Here we show that AtDXO1 possesses both NAD-RNA decapping activity and 5'-3' exonuclease activity but does not hydrolyze the m7 G cap. The atdxo1 mutation increased the stability of NAD-RNAs and led to pleiotropic phenotypes, including severe growth retardation, pale color, and multiple developmental defects. Transcriptome profiling analysis showed that the atdxo1 mutation resulted in upregulation of defense-related genes but downregulation of photosynthesis-related genes. The autoimmunity phenotype of the mutant could be suppressed by either eds1 or npr1 mutation. However, the various phenotypes associated with the atdxo1 mutant could be complemented by an enzymatically inactive AtDXO1. The atdxo1 mutation apparently enhances post-transcriptional gene silencing by elevating levels of siRNAs. Our study indicates that AtDXO1 regulates gene expression in various biological and physiological processes through its pleiotropic molecular functions in mediating RNA processing and decay.

Alternative Farnsworth-Munsell Scoring Methodology for Testing Eyewear

The Farnsworth-Munsell 100 Hue Test (FM100) has been used in clinical and ophthalmic settings for many years. It is a sensitive test for determining individual color defects and is one tool available to the human factors practitioner. However, like many individual evaluation tools developed, it is not completely appropriate as a product assessment tool as is. The FM100 has two main limitations when used as an assessment tool for determining color defects imposed by tinted eyewear such as laser protective lenses. First, the test assumes color defects are bipolar, which is not always true of eyewear. Second, the chromaticity graphs are not always easily understood by non-practitioners. Third, computation of cap scores depends upon adjacent caps, which can absorb or mask differences. A recent assessment of laser protective lens eyewear led to the development of an alternative scoring methodology to remedy the standard score issues when evaluating eyewear.

School screening in Coastal Karnataka

Objective. The objective of this study was to determine the prevalence of visual impairment and blindness among students in 13 schools in coastal Karnataka and to determine the most common causes for the same. Materials and Methods. This was a prospective cross-sectional study. A total of 833 students from 13 different schools were screened as a part of the school screening programme. The examiners were an ophthalmologist and an ophthalmic assistant. For all the students, visual acuity (VA) was measured with a Snellen chart, color vision was done using an Ishiaras chart, fundus examination was done using a direct ophthalmoscope, while students with subnormal vision (VA ≤ 6/ 9) were examined using pinhole, and referred for detailed eye examination and clinical refraction. Results. The age range was from 6 to 16 years comprising 390 males and 443 females. Refractive error in either eye was present in 69 of these students of which myopic astigmatism was the commonest type. This was followed by allergic conjunctivitis 15 cases, amblyopia 3, squint 2, lids and adnexal disorders in 2 students; defective color vision was seen in 8 students, all of whom were males. Spectacle usage was found to be present only in 11 students, who showed lack of awareness concerning eye care and possibly the lack of access to health care. There were no students with retinal or posterior segment disorders. Conclusions. Uncorrected refractive error is the most common visual impairment found in schools students in coastal Karnataka and there is a need for the establishment of a regular school vision-screening program to detect such problems in order to prevent the burden on society due to the long life span ahead.

“I don't like wonky carrots”- an exploration of children's perceptions of suboptimal fruits and vegetables

Children's perceptions of suboptimal fruits and vegetables have not been studied in the suboptimal foods domain. Using two qualitative research methods, this study investigates children's (N = 97) edibility perceptions of suboptimal produce with varied appearance defects. The results show that unlike adult samples previously studied, children are more accepting of suboptimal produce. Defects in shape, size, and certain colour defects were positively perceived, reflecting retailers' opportunities to market suboptimal produce. High levels of brown discolorations and superficial blemishes were not acceptable, implying that produce with such defects could be repurposed as ingredients in foods prepared and sold in-store. These implications reflect retailers' opportunities in marketing suboptimal produce to children, who by their familial influence may also be able to get families to buy and consume suboptimal produce. The importance of familiarity in improving suboptimal food acceptance is also recognised for future research to explore.

Logic NOT gates of the intensity–noise correlation and squeezing in a diamond nitrogen-vacancy center

Color defects in a diamond nitrogen-vacancy (NV) center represent an important physical system for emergent quantum technologies such as logic gates and registers at room temperature. We realized an optical logic NOT gate by inducing a phase shift in a diamond NV center under nonlinear Kerr effect of spontaneous parametric four-wave mixing (SP-FWM). Also, we discussed the intensity–noise correlation and intensity-difference squeezing of SP-FWM and composite signals (SP-FWM+fluorescence) under self-phase modulation (SPM) and cross-phase modulation (XPM) induced by the nonlinear Kerr effect in V-type and double V-type atomic systems. Our experimental results provide an advanced technique of switching contrast by approximately 90%. Different parameters, such as the power of input laser beam and boxcar gate position, were also configured to control the SPM and XPM, which determine the switching phenomenon for correlation and squeezing.

A feasible image-based colorimetric assay using a smartphone RGB camera for point-of-care monitoring of diabetes

Urinary glucose determination using a glucose test strip is simple and convenient in daily self-monitoring of diabetes. However, diabetic patients exhibit acquired impaired color vision (ICV), which results in the inability to discriminate between hues. Even with the assistance of a color chart, it is still not easy for these patients to read the urinary glucose results with the naked eye. In this study, a smartphone camera using an image-based colorimetric detection method was successfully developed for quantitative analysis of urine glucose. A horseradish peroxidase-hydrogen peroxide-3,3′5,5′-tetramethylbenzidine (HRP–H2O2–TMB) system was optimized for a reliable and gradual color fading process via a glucose oxidase (GOD) catalyzed oxidation reaction. The color changes of the peroxidase-H2O2 enzymatic reactions in the 96-well microplate were captured by a smartphone RGB camera with subsequent detection of red, green, and blue (RGB) intensities decreasing at each image pixel. The highly quantitative relationships between the glucose concentrations and the color characteristic values of the blue channel of the captured images were successfully established. The high accuracy of this method was demonstrated in urine glucose measurements with a linear response over the 0.039 mg mL−1 to 10.000 mg mL−1 glucose concentration range and a 0.009 mg mL−1 detection limit. The method has great potential as a point-of-need platform for diabetic patients with defective color vision and features high accuracy and low cost.

Traumatic optic neuropathy in head injury

Introduction: Head injury accounts for approximately 3.4% of all emergency presentations. The role of ocular injuries secondary to head trauma in the causation of blindness continues to be an immense public health problem. This study is aimed to estimate the incidence of traumatic optic neuropathy, to obtain demographic data and to document concurrent injuries in cases of head injury. Materials and Methods: A total of 510 patients presenting with head injury were examined for all the ocular injuries. Severity of head injury which was graded according to Glasgow Coma Scale (GCS). Computed tomography (CT) scan of head was done in all the patients. Visually evoked potential (VEP) was done in patients who had relative afferent pupillary defect (RAPD) and defective color vision. Diagnosis of traumatic optic neuropathy was confirmed on the basis of VEP. Results: Majority of the people affected were males (77.5%). Patients between 16-45 years were affected most. The most frequent site of injury was roadside (72.55%). Ophthalmic involvement was observed in 313 individuals (61.4%). Abnormal uni-ocular color vision was found in 21(4.11%) patients. RAPD was found in 24 (4.70%) patients. VEP was abnormal in 10 (1.96%) patients, of all the cases of head injury. Conclusion: There was a 1.96% incidence of traumatic optic neuropathy in patients of head injury. Among all the ocular findings, eyelid ecchymosis with edema was most common. Intracranial hemorrhage was the most common CT scan finding in head injury patients. Chances of ophthalmic manifestations are much more when there is intracranial bleeding and facial fractures. Keywords: Traumatic optic neuropathy, Head injury.

Polycrystalline diamond photonic waveguides realized by femtosecond laser lithography

In recent years, the perception of diamond has changed from it being a pure gemstone to a universal high-tech material. In the field of photonics, an increased interest is emerging due to its outstanding optical properties, such as its high refractive index, a spectrally wide transmission window, and high Raman coefficient. Furthermore, the capability to host color defects for room temperature single photon generation makes diamond an attractive platform for quantum photonics. Known as nature’s hardest material, the fabrication and handling of crystalline diamond for integrated optics remains challenging. Here, we report on the fabrication of three-dimensional Type III depressed cladding waveguides in polycrystalline diamond substrates by direct laser writing. Single mode waveguiding is demonstrated in the near-infrared telecommunication C-band. We believe that this enables the fabrication of three-dimensional large-scale photonic circuits, which are essential for advanced classical and quantum diamond photonics.

A century of gray: A genomic locus found in 2 distinct Pseudomonas spp. is associated with historical and contemporary color defects in dairy products worldwide

Some gram-negative bacteria, including Pseudomonas spp., can grow at refrigeration temperatures and cause flavor, odor, and texture defects in fluid milk. Historical and modern cases exist of gray and blue color defects in fluid milk due to Pseudomonas, and several recent reports have detailed fresh cheese spoilage associated with blue-pigment-forming Pseudomonas. Our goal was to investigate the genomes of pigmented Pseudomonas isolates responsible for historical and modern pigmented spoilage of dairy products in the United States to determine the genetic basis of pigment-forming phenotypes. We performed whole genome sequencing of 9 Pseudomonas isolates: 3 from recent incidents of gray-pigmented fluid milk (Pseudomonas fluorescens group), 1 from blue-pigmented cheese (P. fluorescens group), 2 from a historical blue milk spoilage incident (Pseudomonas putida group), and 3 with no evidence for blue or gray pigment formation (2 from P. fluorescens group and 1 from Pseudomonas chlororaphis group). All 6 isolates collected from products with a gray or blue pigment defect were confirmed to produce pigment using potato dextrose agar or pasteurized milk. A subset of 2 isolates was selected for inoculation into milk and onto the surface of a model cheese for subsequent color measurement. These isolates produced different colors on potato dextrose agar, but produced nearly identical color defects in milk and on model cheese. For the same subset of 2 isolates, the gray color defect in milk was produced only in containers with ample headspace and not in full containers, suggesting that oxygen is vital for pigment formation. This work also demonstrated that a Pseudomonas isolate from cheese can produce a pigment defect in milk, and vice versa. Comparative genomics identified an accessory locus encoding tryptophan biosynthesis genes that was present in all isolates that produced gray or blue pigment under laboratory conditions and was only previously reported in 2 P. fluorescens isolates responsible for blue mozzarella in Italy. Because this locus was found in genetically distant isolates belonging to different Pseudomonas species groups, it may have been acquired via horizontal gene transfer. These data suggest that several past and present gray- or blue-pigmented dairy spoilage events share a common genetic etiology that transcends species-level identification and merits further investigation to determine mechanistic details and modes of prevention.

A REVIEW OF VISION BASED DEFECT DETECTION USING IMAGE PROCESSING TECHNIQUES FOR BEVERAGE MANUFACTURING INDUSTRY

Vision based quality inspection emerged as a prime candidate in beverage manufacturing industry. It functions to control the product quality for the large scale industries; not only to save time, cost and labour, but also to secure a competitive advantage. It is a requirement of International Organization for Standardization (ISO) 9001, to appease the customer satisfaction in term of frequent improvement of the quality of products and services. It is totally impractical to rely on human inspector to handle a large scale quality control production because human has major drawback in their performance such as inconsistency and time consuming. This article reviews defect detection using image processing techniques for beverage manufacturing industry. There are comparative studies on techniques suggested by previous researchers. This review focuses on shape defect detection, color concentration inspection and level of liquid products measurement in a container. Shape, color and level defects are the main concern for bottle inspection in beverage manufacturing industry. The development of practical testing and the services performance are also discussed in this paper.

Transformation and Formation of Radiation-Induced Point Defects in Irradiated Lithium Fluoride Crystals After Their Mechanical Fragmentation

Changes in the concentrations of ordinary radiation defects and formation of near-cluster radiation defects (color centers) are shown to occur in nanocrystals fabricated by mechanical fragmentation of irradiated LiF crystals. Concentrations of near-cluster color centers increase to a steady value after fragmentation and remain constant at room temperature for a long time. UV irradiation of fabricated nanocrystals after termination of center formation processes in them causes the concentration of near-cluster defects containing three anion vacancies and two electrons to increase significantly. It is demonstrated that there are single-vacancy color centers as well as ordinary and near-cluster aggregate centers in unirradiated nanocrystals fabricated by fragmentation of unirradiated crystals.

Evaluation of Aircrew Low-Intensity Threat Laser Eye Protection

Prototype low-intensity threat laser eye protection (LIT-LEP) spectacles were evaluated for US Coast Guard (USCG) cockpits and night vision goggle compatibility. The impetus for interest in aviation LIT-LEP is driven in part by the fact that easily accessible 0.5-2.0 W high-power laser pointers exceed safety standards for direct on-axis viewing. A repeated-measures experimental design was used to assess LIT-LEP performance relative to a no-LEP control for the following tasks: Near- and far contrast acuity, night vision goggle far-contrast acuity, emissive and non-emissive light source color-vision screening, and USCG multifunctional display color symbol discrimination reaction time and accuracy. Near- and far-contrast acuity results demonstrated good LIT-LEP performance for typical in- and out-of-cockpit lighting conditions. Night vision goggle performance suffered marginally at only one contrast level (85%; 20/30 acuity line). Color vision test results showed good color balance in that S-, M-, and L-cone performance did not demonstrate a clinical diagnostic color defect for emissive or non-emissive light sources when wearing LIT-LEP. Color symbol discrimination reaction-time-task results based on inverse efficiency scores revealed that some non-primary flight display colors exhibited a combination of slower speed and decreased accuracy. The findings will contribute to an acquisition decision as well as guide future LEP designs.

Efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test

BackgroundThe aim of this study was to evaluate the efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test (MLT). MethodsThirty subjects with a known color vision defect were enrolled after consent. The color vision was assessed using Ishihara test, D15 test, and MLT. The error scores were recorded. The test was repeated after using a red contact lens. ResultsThe mean error scores were 7.87 (±1.00), 3.33 (±3.15), and 5.67 (±2.52) on Ishihara, MLT, and D15 test, respectively. The error scores reduced to 3.93 (±3.78), 1.33 (±1.34), and 2.77 (±2.12) Ishihara, MLT, and D15 test, respectively (P value < 0.05, Wilcoxon rank test). None of the subjects were in color perception (CP) II at presentation but 47.5% became CP II with the lens on Ishihara test. Ninety percent could pass the MLT CP III standard. ConclusionThis study shows that red lens reduced error scores and subjects could pass the color vision tests. Notwithstanding the improvement in performance on color vision tests, lens is not recommended for personnel on active combat duty. The recruiting medical officer needs to be aware of the fact that a subject with defective color vision can pass various tests with a red contact lens.

Spans of fundamental colors for people with defective color

Spans of fundamental colors for people with defective color

Effect of pruning season and tool on knot occlusion and stem discolouration in &lt;i&gt;Betula pendula&lt;/i&gt; – situation five years after pruning

This paper investigates and models the effects of pruning season and tool on wound occlusion with varying tree and branch characteristics of silver birch (Betula pendula Roth) stems at the pruning height of 0−4 metres. Dates of eight secateurs prunings, three saw prunings and two sticks prunings as well as unpruned control were tested in permanent plots on four sites. Knot occlusion and discolouration in stemwood were measured from about 1600 studied knots of 112 sample trees felled five to six years after pruning in 2010. Knot occlusion rate was modelled according to pruning tool, date, tree growth, and branch characteristics. The occlusion was the fastest in trees pruned in spring or early summer, and the slowest in trees pruned in autumn. Stubs of living branches occluded faster than the dead ones with the same diameter. Saw pruning resulted in clearly better occlusion rates than secateurs pruning, caused by the shorter knot stubs after saw pruning. Hitting dead branches away with a stick resulted in the worst occlusion status. The colour defects spread more often upward from the knot than downward. Discolouration in stemwood was detected more frequently near to the pruned branches than the unpruned ones, and more widely near to the stubs of dead branches than the living ones. Most saw and secateurs pruned branches were completely occluded during the experiment, so these prunings were suitable for all branches under 20 mm in diameter, and for living branches even up to 30 mm in fast-growing trees.

Yield Improvement in Color Filter Manufacturing Using Taguchi Methods and TRIZ’s Substance–Field Analysis

Thin-film transistor liquid crystal display (TFT-LCD) has been widely applied to electronic merchandise in daily lives. All panel makers are trying every possible way to produce high-quality products to fight for market share. However, the particle issue in the clean room often causes scrapped panel and increased costs. In the past, engineers in factory usually carried out quality improvement via the trial-and-error and empirical method, yet the results were rather poor, which often delayed the schedule of mass production of new product. A problem-solving procedure has been proposed in this paper, and we use a TFT-LCD maker as an example to explain the effectiveness of this procedure. The particle and gel defects in the process critical to quality are defined via the historical data analysis of the case company. The statistical analysis is utilized to screen out the factors with a significant impact on defective color filter (CF), Taguchi methods are used to find out optimal parameters combination, and the substance–field analysis in the Teoriya Resheniya Izobretatelskikh Zadatch (Russian) and 76 standard solutions come up with the optimal improvement plan to verify the effectiveness of improvement. Finally, the obtained improvement plan is standardized, and a relevant operating standard is revised. The results indicate that the process yield of CF has been improved, which has led to a hard saving of more than U.S. $3.7 million.

Optical Detection of Green Emission for Non-Uniformity Film in Flat Panel Displays

Among colours, the green colour has the most sensitivity in human vision so that green colour defects on displays can be effortlessly perceived by a photopic eye with the most intensity in the wavelength 555 nm of the spectrum. With the market moving forward to high resolution, displays can have resolutions of 10 million pixels. Therefore, the method of detecting the appearance of the panel using ultra-high resolutions in TFT-LCD is important. The machine vision associated with transmission chromaticity spectrometer that quantises the defects are explored, such as blackening and whitening. The result shows the significant phenomena to recognize the non-uniformity of film-related chromatic variation. In contrast, the quantitative assessment illustrates that the just noticeable difference (JND) of chromaticity CIE xyY at 0.001 is the measuring sensitivity for the chromatic variables (x, y), whereas JND is a perceptible threshold for a colour difference metric. Moreover, an optical device associated with a 198Hg discharge lamp calibrates the spectrometer accuracy.

Colour Vision Status of Staff Working with Radiation in Public Hospital

Growing application of radiation sources and lack of awareness among workers in practicing protective measures imply an increased risk of radiation exposure to eye. This study determined the status of colour vision and its association with working duration amongst staff working with radiation in a university hospital. A total of 55 employees (28 exposed (RS) and 27 not directly exposed to radiation (NRS)) were recruited and 30 employees were used as controls. Visual acuity (VA) was measured using Snellen chart. Colour vision assessments were conducted using Ishihara plates, D15 panel and FM 100 hues and the results were analysed using one way ANOVA. The subjects’ age ranged between 29 and 44 years old. Mean VA for all subjects was 6/6. More than 50% of the subjects has colour defects, 3.45% of RS failed D15, 37.93% failed FM 100 hue, 7.4% of NRS failed D15 and 55.56% failed FM 100 hue. Significant difference was found in the total error scores between RS (77.10 ± 6.05) and NRS (84.89 ± 7.76) with the controls (41.47 ± 3.10) [ANOVA F(2,83)=16.084, p=0.00]. There was no association between working duration and severity of colour defect [r(104)= -0.123, p>0.05]. This study concludes that majority of the studied subjects has color deficiency but not significantly correlated with their working duration. Protective measures need to be taken to improve the situation.