SEARCH · PubMed Health

Results for “Color”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources

PubMed2006

Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis.

The Himalayan blue poppy, Meconopsis grandis, has sky blue-colored petals, although the anthocyanidin nucleus of the petal pigment is cyanidin. The blue color development in this blue poppy involving ferric ions was therefore studied. We analyzed the vacuolar pH, and the organic and inorganic components of the colored cells. A direct measurement by a proton-selective microelectrode revealed that the vacuolar pH value was 4.8. The concentrations of the total anthocyanins in the colored cells were around 5mM, and ca. three times more concentrated flavonols were detected. Fe was detected by atomic analysis of the colored cells, and the ratio of Fe to anthocyanins was ca. 0.8 eq. By mixing the anthocyanin, flavonol and metal ion components in a buffered aq. solution at pH 5.0, we were able to reproduce the same blue color; the visible absorption spectrum and CD were identical to those in the petals, with Fe(3+), Mg(2+) and flavonol being essential for the blue color. The blue pigment in Meconopsis should be a new type of metal complex pigment that is different from a stoichiometric supramolecular pigment such as commelinin or protocyanin.

Anthocyanins↗

PubMed2004

Influence of acidulated phosphate fluoride solution on the color stability of indirect composites.

STATEMENT OF PROBLEM: Although acidulated phosphate fluoride (APF) agents are known to be useful for caries-preventive interventions, few studies have examined the influence of APF agents on indirect composite materials. PURPOSE: This study examined whether exposure to APF agents affects color stability when a composite is exposed to a common staining agent. MATERIALS AND METHODS: Forty light-polymerized composite disks (8 x 2.0 mm) were fabricated with midifilled (Cesead II; n = 20) and microfilled (Newmetacolor Infis; n = 20) composites. The specimens were polymerized with a light for 90 seconds on each side, ground with silicon carbide paper, finished using a polishing kit, and colorimetrically evaluated to determine baseline L*a *b* values. After storage in distilled water at 37 degrees C for 24 hours, half of the disks for each composite (n = 10) was treated with an APF solution (Fluodent A) for 32 minutes, while the remaining half of the specimens were untreated (controls). Half the treated and untreated specimens were immersed in tea or distilled water (n = 5, respectively), and after 4 weeks color changes were measured. To determine the influence of APF on each composite, the CIE L*a*b* color difference baseline values after 4 weeks were compared using 2- and 1-way analyses of variance and post-hoc Sheffe's S intervals (alpha=.05). RESULTS: The color differences of both materials when immersed in tea were significantly influenced by APF (P < .05). The mean DeltaE values of APF-treated Cesead II and Newmetacolor Infis immersed in tea were 5.4 +/- 1.2 and 4.5 +/- 1.3, respectively, while the untreated values were 3.8 +/- 0.6 and 3.0 +/- 0.1, respectively. When immersed in water, neither material was affected by APF in respect to change in color. CONCLUSION: The color of both composites tested were significantly influenced by APF treatment when immersed in tea, indicating that the in vitro color stability of the indirect composites was negatively affected by applications of APF.

Acidulated Phosphate Fluoride↗

PubMed2007

Color Doppler US pulmonary artery vessel signal: a sign for predicting the benign lesions.

The lung cancer blood supply originates from the bronchial artery. If vessel signals within pulmonary lesions can be confirmed to be those of the pulmonary artery, color Doppler ultrasound (US) should be able to predict and differentiate benign lesions from lung cancers. Two hundred sixty-four patients with abutting thoracic lesions (including 125 lung cancers and 139 benign lesions) underwent color Doppler US examinations. A pulsatile flow, with the vessel signal length on sonographic appearance > or =1 cm demonstrated by color Doppler US, was arbitrarily defined as a pulmonary artery vessel signal. Of the 264 thoracic lesions, 73 (58%) lung cancers and 107 (77%) benign lesions had detectable color Doppler US pulsatile flow vessel signals. Analyzing the pulsatile flow vessel signals, the color Doppler US pulmonary artery vessel signal was present in 74 (53%) benign lesions, but was found in only two (2%) lung cancers of a specific alveolar cell carcinoma with lobar consolidation. Using the pulmonary artery vessel signal, color Doppler US can be valuable in predicting and differentiating benign lesions from lung cancers (p < 0.0001, sensitivity = 0.53, specificity = 0.98 and positive likelihood ratio 26.5). In conclusion, color Doppler US pulmonary artery vessel signal sign is useful in predicting and differentiating benign lesions from lung cancers.

Adolescent↗

PubMed2005

The watercolor effect: quantitative evidence for luminance-dependent mechanisms of long-range color assimilation.

When a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour, the brighter color will spread into the entire enclosed area. This is known as the watercolor effect (WCE). Here we quantified the effect of color spreading using both color-matching and hue-cancellation tasks. Over a wide range of stimulus chromaticities, there was a reliable shift in color appearance that closely followed the direction of the inducing contour. When the contours were equated in luminance, the WCE was still present, but weak. The magnitude of the color spreading increased with increases in luminance contrast between the two contours. Additionally, as the luminance contrast between the contours increased, the chromaticity of the induced color more closely resembled that of the inside contour. The results support the hypothesis that the WCE is mediated by luminance-dependent mechanisms of long-range color assimilation.

Adult↗

PubMed2004

Return sludge employed in enhancement of color removal in the integrally industrial wastewater treatment plant.

In this study, the recirculation of chemical sludge and integrated sludge were employed for enhancement of color removal in an integrally industrial wastewater treatment plant. The jar test was conducted for simulating chemical coagulation process with different coagulants, aluminum sulfate and polyaluminum chloride (PACl), after different activated sludge systems (with air or high-purity oxygen). The results showed that with sludge recirculation the process of coagulation for the color removal has up to 35% enhancement in comparison with no sludge recirculation. Meanwhile, the color removal enhancement of coagulant aluminum sulfate was approximately 2 to 3-times the color removal enhancement of coagulant PACl at the optimum ratio of return sludge. In coagulation process with influent color of 1220 true color unit (TCU), the optimum dosage of return sludge was 3010mg/L, when coagulant PACl or aluminum sulfate was employed. In coagulation process with influent color of 536 TCU, the optimum dosages of return sludge were 2340 and 4680mg/L using PACl and aluminum sulfate, respectively.

Alum Compounds↗

PubMed2006

Does binding of synesthetic color to the evoking grapheme require attention?

The neural mechanisms involved in binding features such as shape and color are a matter of some debate. Does accurate binding rely on spatial attention functions of the parietal lobe or can it occur without attentional input? One extraordinary phenomenon that may shed light on this question is that of chromatic-graphemic synesthesia, a rare condition in which letter shapes evoke color perceptions. A popular suggestion is that synesthesia results from cross-activation between different functional regions (e.g., between shape and color areas of the ventral pathway). Under such conditions binding may not require parietal involvement and could occur preattentively. We tested this hypothesis in two synesthetes who perceived grayscale letters and digits in color. We found no evidence for preattentive binding using a visual search paradigm in which the target was a synesthetic inducer. In another experiment involving color judgments, we show that the congruency of target color and the synesthetic color of irrelevant digits modulates performance more when the digits are included within the attended region of space. We propose that the mechanisms giving rise to this type of synesthesia appear to follow at least some principles of normal binding, and even synesthetic binding seems to require attention.

Adult↗

PubMed2003

Variability of porcelain color reproduction by commercial laboratories.

STATEMENT OF PROBLEM: Many investigations in the field of metal ceramics have examined materials, manipulative variables, and the relationship of these factors to a restoration's color. However, the effect of the artistic component of restoration fabrication is not known. PURPOSE: The purpose of this study was to determine through instrumental colorimetry the variability in color reproduction for metal ceramic crowns fabricated by commercial dental laboratory technicians. MATERIALS AND METHODS: Fifty metal ceramic crowns were fabricated on standardized metal frameworks to the same shade specifications by 5 commercial dental laboratories (n=10). Laboratory prescriptions requested that the technician match the shade and translucency of a provided Vita Lumin A3.5 shade tab. Technicians used the porcelain and technique of their own selection to match the tab. Color differences were determined by use of a colorimeter between crowns and the prescribed shade tab at middle and incisal sites. Analysis of variance was used to determine whether differences in color reproduction existed among laboratories. Where statistically significant interactions existed, the Tukey honestly significant difference test was used to determine significant differences between laboratories according to sites (alpha=.05). RESULTS: Color reproduction was significantly different (P <.0001) among laboratories for both sites. Mean color difference from shade tabs ranged from 3.5 to 11.1 DeltaE units. All laboratories were better at matching shades in the incisal third of the crown. CONCLUSION: Within the limitations of this study, the ability to reproduce the color of the target shade tab differed among laboratories. Most crowns fabricated by the laboratories in this study, when compared to the prescribed shade tab, were above the clinical threshold for an acceptable shade match under intraoral conditions (DeltaE 3.7).

Analysis of Variance↗

PubMed1997

Effects of chemical disinfectants on the surface characteristics and color of denture resins.

PURPOSE: Because dentures are disinfected repeatedly and for various amounts of time, it was of clinical interest to determine whether chemical disinfectants altered the surface texture or inherent color. MATERIAL AND METHODS: Five chemical disinfectants (Clorox, Banicide, Cidex-7, Biocide, and Multicide) in combination with five denture resins (Dentsply reline material, Hygenic HyFlo, Hygenic Perm, Lucitone 199, and Triad VLC reline resin) were evaluated at four different times of immersion (10 minutes, 30 minutes, 24 hours, and 7 days). Changes from baseline for surface roughness and color were recorded. Surface roughness data were recorded with a surface analyzer. Color data in CIE L*a*b* color space were measured with a colorimeter. Data were analyzed with repeated-measures analysis of variance and single-factor analysis of variance. RESULTS: Although statistical differences were demonstrated among disinfectants and resins for both measured parameters, the magnitudes of change in color and roughness was most often clinically insignificant. CONCLUSIONS: One disinfectant (Multicide) cannot be used on all five resins, and the remaining four disinfectants can be used on any of the five resins for up to a period of 30 minutes. All resins tested can be immersed in the four remaining disinfectants for up to 30 minutes without appreciable alteration to surface texture or color. Lucitone 199 resin can be immersed in any of the four disinfectants for up to 7 days without perceivable color change.

Acrylic Resins↗

PubMed1999

Effects of chemical disinfectants on surface characteristics and color of three fixed prosthodontic crown materials.

STATEMENT OF PROBLEM: Dental restorations should reproduce similar optical effects as natural tooth structure to achieve a good color match. Mismatch can result in unsatisfactory shade matching. PURPOSE: This study determined whether chemical disinfectants affected the surface texture and color of 3 fixed prosthodontic materials. MATERIAL AND METHODS: Five chemical disinfectants (Clorox, Banicide, Cidex-7, Biocide, and Multicide) in combination with 3 restorative materials (Dicor, Vita VMK ceramometal porcelain, Midas ADA type III noble casting alloy) were evaluated at 4 different times of immersion (10 minutes, 30 minutes, 24 hours, and 7 days). Changes from baseline for surface roughness and color were evaluated. Surface roughness data were recorded with a surface analyzer and color data in CIE L*a*b* color space were measured with a colorimeter. Data were analyzed with repeated measures analysis of variance and single factor analysis of variance. RESULTS: There were no statistical differences in surface roughness among disinfectants and restorative materials. However, there were statistical differences of changes in color, increase in deltaE and decrease in deltaL, among disinfectants and the noble casting alloy. CONCLUSION: Only 2 of the 3 materials evaluated, Dicor and Vita VMK ceramometal porcelain, can be used with all 5 disinfectants up to 7 days of immersion. Three chemical disinfectants (Biocide, Clorox, and Multicide) caused clinically significant color changes with the noble casting alloy after 7 days of immersion.

Analysis of Variance↗

PubMed1999

Assessment of the functional role of accessory pudendal arteries in erection by transrectal color Doppler ultrasound.

PURPOSE: Anatomical studies have demonstrated accessory pudendal arteries originating from supralevator vessels in about two-thirds of men. Injury to accessory pudendal arteries derived from inferior vesical and obturator arteries has been reported to be responsible for vasculogenic impotence after nerve sparing radical prostatectomy. We performed transrectal and perineal color Doppler ultrasound in patients before radical pelvic surgery to identify accessory pudendal arteries and assess their functional role during erection. MATERIALS AND METHODS: A total of 12 patients with a mean age of 60 years were examined before radical prostatectomy (10) or cystoprostatectomy (2). Transrectal and perineal color Doppler flow imaging and spectral waveform analysis were performed. Peak systolic velocity, end diastolic velocity, resistive index and arterial diameter were measured before and during pharmacologically induced erection. Transrectal color Doppler ultrasound data were compared with intraoperative findings. RESULTS: Transrectal color Doppler ultrasound visualized accessory pudendal arteries derived from supralevator arteries in 9, and prostatic and seminal vesicle arteries in all patients. Perineal color Doppler ultrasound visualized internal pudendal arteries in all patients. After intracavernosal injection of papaverine accessory and internal pudendal arteries displayed similar significant hemodynamic changes. Diameter as well as peak systolic and end diastolic velocities increased, and resistive index decreased. Prostatic and seminal vesicle arteries showed no significant change. Presence and location of accessory pudendal arteries demonstrated by transrectal color Doppler ultrasound were confirmed by intraoperative findings. CONCLUSIONS: During pharmacologically induced erection hemodynamic changes in accessory and internal pudendal arteries are similar to those described in cavernous arteries, thus demonstrating the functional role of accessory pudendal arteries in penile erection. Color Doppler ultrasound appears to be reliable to examine internal and accessory pudendal arteries based on morphological and functional criteria.

Aged↗

PubMed2004

In vitro evaluation of color change in maxillofacial elastomer through the use of an ultraviolet light absorber and a hindered amine light stabilizer.

STATEMENT OF PROBLEM: External prostheses composed of silicone elastomers exhibit an unwanted color change over time. PURPOSE: This study evaluated color stability when an ultraviolet light absorber and hindered amine light stabilizer were mixed in the maxillofacial elastomer containing either organic or inorganic pigments. MATERIAL AND METHODS: The materials used were an RTV silicone elastomer, 1 natural inorganic dry-earth pigment (burnt sienna) and 2 synthesized organic pigments (hansa yellow and alizarin red), ultraviolet light absorber (UVA) and hindered amine light stabilizer (HALS). Specimens (n=160) were fabricated in a custom mold and randomly assigned and exposed to weathering sites in Miami and Phoenix for approximately 3 months. Eight test groups (2 of each 4 material types with or without additives) of 10 specimens each were assigned to each site. L*, a*, b* readings were obtained before and after weathering from a spectrocolorimeter. Nonpigmented elastomers served as the control. Three-factor ANOVA was conducted to examine interaction effects between weathering sites, specimen type, and the presence of additive (alpha=.05). Overall color change (Delta E) and change in color coordinates (Delta L*, Delta a*, Delta b*) of specimen groups with and without additive were analyzed with independent sample t tests. RESULTS: In specimen groups with the additives (UVA and HALS), color change decreased significantly (P<.05) in burnt sienna and hansa yellow in Phoenix and in the control and hansa yellow in Miami. Additives did not affect color change in the alizarin red group. CONCLUSION: UVA and HALS were shown to be effective in retarding color change in some circumstances.

Absorption↗

PubMed2002

Color-selective analysis of luminance-varying stimuli.

Alternating adaptation to red and green luminance-varying gratings of different spatial frequencies simultaneously induces opposing color-selective size aftereffects (Blakemore & Sutton, 1969) in the same retinal locus. With single-color adaptation, the aftereffect is larger and affects test patterns of both colors, though not equally. The color-insensitive portion of the effect shows very substantial interocular and cross-orientation transfer. The color-selective aftereffect, which accounts for about 1/3 of the total effect, is highly selective for both orientation and eye of origin. Thus, both color-selective and color-insensitive mechanisms participate in determining the perceptual characteristics of luminance-varying patterns.

Adaptation, Ocular↗

PubMed2003

The influence of color on the perception of luminance motion.

We examined the role of color in the processing of motion of a luminance-varying pattern by alternating the color of a moving pattern and measuring the luminance contrast required for accurate discrimination of the motion direction. We report that the contrast threshold for perceiving the direction of motion of luminance-varying patterns is greatly elevated when the mean chromaticity of the moving luminance pattern alternates between two hues. Thus, color plays a critical role in the discrimination of luminance motion direction. The magnitude of the threshold elevation is directly related to the magnitude of the LM opponent color contrast produced by the color alternation. S-cone contrast produces little or no effect. The interference produced by color alternation was greatly reduced in the retinal periphery. Our results indicate that first-order luminance motion mechanisms are sensitive to the color of moving objects as coded by a differencing of the outputs of L and M cones. Contrary to the widely accepted notion that luminance-defined motion is processed primarily in the spectrally broadband magnocellular (M) pathway, our results suggest that the hue-selective parvocellular (P) mechanisms provide input to first-order motion detectors.

Color Perception↗

PubMed2003

Attentional selection of superimposed surfaces cannot be explained by modulation of the gain of color channels.

When two differently colored, superimposed patterns of dots rotate in opposite directions, this yields the percept of two superimposed transparent surfaces. If observers are cued to attend to one set of dots, they are impaired in making judgments about the other set. Since the two sets of dots are overlapping, the cueing effect cannot be explained by spatial attention. This has led to the interpretation that the impairment reflects surface-based attentional selection. However, recent single-unit recording studies in monkeys have found that attention can modulate the gain of neurons tuned for features such as color. Thus, rather than reflecting the selection of a surface, the behavioral effects might simply reflect a reduction in the gain of color channels selective for the color of the uncued set of dots (feature-based attention), as if viewing the surfaces through a colored filter. If so, then the impairment should be eliminated when the two surfaces are made the same color. Instead, we find that the impairment persists with no reduction in strength. Our findings thus rule out the color gain explanation.

Adult↗

PubMed1997

Adaptation and the color statistics of natural images.

Color perception depends profoundly on adaptation processes that adjust sensitivity in response to the prevailing pattern of stimulation. We examined how color sensitivity and appearance might be influenced by adaptation to the color distributions characteristic of natural images. Color distributions were measured for natural scenes by sampling an array of locations within each scene with a spectroradiometer, or by recording each scene with a digital camera successively through 31 interference filters. The images were used to reconstruct the L, M and S cone excitation at each spatial location, and the contrasts along three post-receptoral axes [L + M, L - M or S - (L + M)]. Individual scenes varied substantially in their mean chromaticity and luminance, in the principal color-luminance axes of their distributions, and in the range of contrasts in their distributions. Chromatic contrasts were biased along a relatively narrow range of bluish to yellowish-green angles, lying roughly between the S - (L + M) axis (which was more characteristic of scenes with lush vegetation and little sky) and a unique blue-yellow axis (which was more typical of arid scenes). For many scenes L - M and S - (L + M) signals were highly correlated, with weaker correlations between luminance and chromaticity. We use a two-stage model (von Kries scaling followed by decorrelation) to show how the appearance of colors may be altered by light adaptation to the mean of the distributions and by contrast adaptation to the contrast range and principal axes of the distributions; and we show that such adjustments are qualitatively consistent with empirical measurements of asymmetric color matches obtained after adaptation to successive random samples drawn from natural distributions of chromaticities and lightnesses. Such adaptation effects define the natural range of operating states of the visual system.

Adaptation, Ocular↗

PubMed1997

Color Doppler imaging in predicting the biologic behavior of prostate cancer: correlation with disease-free survival.

OBJECTIVES: We investigated the association of transrectal color Doppler imaging (CDI) signal detection in localized prostate cancer with biologic behavior as assessed by tumor Gleason grade, seminal vesicle invasion, capsular and margin status, and actuarial biochemical freedom from relapse. METHODS: From 1991 to 1996, transrectal ultrasound with CDI and biopsy was performed in 2718 men using a 7.0-MHz probe optimized to detect color-coded blood flow within the gland and along the capsular margin. Color flow was graded on a scale from 0 to 2+, with 0 and 1+ representing no detectable flow and normal flow, and 2+ indicating increased flow. Color flow maps were constructed in 47 men with clinically localized prostate cancer treated by radical prostatectomy (RP) and compared to their whole mount RP specimen step sections. RESULTS: Color flow detected within the index tumor was graded as 2+ in 22 of 47 patients and 0 or 1+ in the remaining 25. Tumors graded 2+ correlated with higher Gleason grade, higher incidence of seminal vesicle invasion, and higher relapse rate, with only 11 of 22 patients disease free based on undetectable prostate-specific antigen (PSA) levels. In contrast, 24 of 25 patients with tumors graded 0 or 1+ are free of biochemical relapse with a median follow-up of 30.9 months. Patients with increased flow were 10.2 times more likely to relapse even after correction for other prognostic variables. In addition, tumors with 2+ capsular flow correlated with a higher incidence of non-organ-confined disease. CONCLUSIONS: Color-coded Doppler flow within the tumor and overlying capsule appears to correlate with both tumor grade and stage, respectively. Detection and grading of color-coded flow within biopsy-proven cancers may identify patients with a high likelihood of biochemical relapse.

Adenocarcinoma↗

PubMed1997

An electrophysiological study of the selection of the color and shape of alphanumeric characters in response choice.

We examined the functional and temporal organization of task-directed selective processing of the color and shape of alphanumeric characters. Dependent variables were measures derived from event-related brain potentials (onset latency of selection negativity (SN) and the lateralized readiness potential). We found SNs related to the relevance for correct task-performance of the color, the global shape and the local shape of the characters. The onset latencies of these SNs suggested that color and global shape were identified at the same time and earlier than local shape. The absence of an SN to global shape if the color was irrelevant suggested that selection on the basis of the global shape depended hierarchically on that of color. Selection of the local shape was independent of color relevance. The lateralized readiness potentials suggested that response selection occurred when the conjunction of color, global shape and local shape had been identified. No evidence was found for temporal overlap between stimulus identification and response selection. These findings show that selective task-directed processing can be studied at multiple levels in a single paradigm. They are inconsistent with the central assumption of several continuous information transmission models that relevant partial information is used to activate associated responses as soon as it becomes available.

Adult↗

PubMed2003

Transrectal ultrasound color Doppler in the evaluation of recurrence of anal canal cancer.

OBJECTIVE: aim was to obtain elements for a differential diagnosis between post-radiation fibrosis and residual tumor or local relapse in anal canal cancer through detection of presence/absence of intralesional blood flow. Transrectal ultrasound and color Doppler were compared. METHODS: 43 patients underwent transrectal ultrasound sonography and color Doppler before and after therapy to assess intralesional blood flow and flow pattern (spotty and linear signals). All diagnostic imaging results were compared to histological analysis. Specificity was submitted to statistical analysis using McNemar test. RESULTS: before therapy 34 lesions (79%) showed color signal; no signal in 9 (21%), which were excluded from our analysis. Eighteen of the 34 patients considered, presented complete response to therapy, 14 partial response and two no response. After therapy, signal disappeared in 17 patients (94%); one false-positive (6%) presented spotty signals; 16 of 34 patients presented changed color signal. Color Doppler showed higher specificity than grey scale transrectal ultrasound in the differentiation of fibrosis from tumor. Response was confirmed by histological examination, considered gold standard. McNemar test demonstrated the significance of color Doppler (P < 0.0001). CONCLUSION: color Doppler considerably increases transrectal ultrasound specificity in differentiating tumor relapse from fibrosis in anal canal cancer.

Anal Canal↗