Ontogeny of biological order.
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Biological Evolution↗
Biomedical subjects
B K Davis
Publications and source records attributed to B K Davis.
Allele frequencies in a cat population in Budapest.
Allelic frequencies were determined for the domestic cat population of Budapest, Hungary. Most of the frequencies are in the range of those of western European populations, but there are two unusual features. The first is the apparent absence of blotched tabby and a relatively high frequency of Abyssinian tabby. The second is in the distribution of frequencies of white spotting phenotypes. There is an approximately normal distribution around the most common pattern, which is 50 percent white fur, contrasted to western populations in which frequency is maximal between approximately 10-30 percent white fur and declines with increasing white fur.
Alleles↗
Asymmetry in sister chromatids of human chromosomes.
Human metaphase chromosomes show identical lateral bands in sister chromatids when stained with quinacrine mustard or with Giemsa after trypsin treatment. A hybrid of these two methods produces banding patterns that are different in sister chromatids. Homologs may have similar patterns, so that a given chromatid is more like a homologous chromatid than its sister chromatid. It is suggested that asymmetry of sister chromatids may be important in regular mitotic disjunction.
Chromatids↗
Colorimetric evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers.
The effect of porcelain veneer opacity on the resultant shade of a veneer-substrate system was evaluated colorimetrically. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted resin composite luting agent. A custom shade guide was fabricated. All samples were analyzed with a Chrome Meter using Munsell and CIE LAB notation. ANOVA showed significant differences (P less than .05) for each coordinate in both the Munsell and CIE LAB color space for all groups. The smallest delta E*ab for all groups was noted with shade tab C2. The resultant shade was neither the shade of the porcelain (A1) nor the substrate (C4). The data indicate that the translucent porcelain has as great or greater effect on the color coordinates of the veneer-substrate system as the substrate material.
Analysis of Variance↗
Subjective evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers.
The effect of porcelain veneer opacity on the resultant shade of a veneer/substrate system was subjectively evaluated. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted composite resin luting agent. Clinicians were instructed to match samples with a custom and a commercial shade guide, and to sort veneers into groups of similar shade. The Farnsworth-Munsell 83 Hue test was used to measure the clinicians' color vision. Results indicated that the participants were unable to distinguish any difference between veneer groups (kappa = 0.33). Shade C2 was the predominant shade chosen for all groups. All veneers provided some masking of the underlying substrate. Varying the percentage of translucent porcelain had little effect on the final shade assessment.
Color↗
Kubelka-Munk reflectance theory applied to porcelain veneer systems using a colorimeter.
The purpose of this study was to demonstrate the ability of Kubelka-Munk reflectance theory to predict color parameters of veneer porcelain on various backings using colorimetric measurements. Tristimulus absorption and scattering coefficients were used to predict the respective tristimulus reflectance values of A1, D3, and translucent porcelain samples after they had been bonded to light and dark substrates using universal, opaque, and untinted shades of bonding resin. Observed and predicted reflectance values exhibited high correlation (r2 > or = 0.93 for each porcelain shade). Kubelka-Munk theory offers an accurate prediction for the resultant colorimetric reflectance parameters of veneer porcelain bonded to variously colored backings.
Absorption↗
Environmental transformation of toxic metals.
Because toxicity varies enormously with the chemical state of metals, transformations in the environment control the level of the human health hazard. Important transformation processes include adsorption and desorption from soils and sediments, oxidation and reduction (redox) reactions, biotic metabolism, formation of organic metal compounds, and bioaccumulation. The six metals detailed in this chapter--arsenic, cadmium, chromium, lead, mercury, and selenium--were chosen because of their toxicity, frequency of occurrence at hazardous waste sites, and involvement in environmental contamination.
Animals↗