Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.

The effect of increasing cement thickness on the fracture strength of aluminous porcelain jacket crowns was investigated in this study. Thirty-three aluminous porcelain jacket crowns were divided into three groups. In Group 1, only platinum foil was used to provide cement space. In Group 2 two layers and Group 3 four layers of die spacer were painted onto the metal die before impression taking. Each crown was cemented onto a metal die with zinc phosphate cement and loaded until fracture. The maximum force to break each crown was recorded. The average fracture load was 408 N for Group 1,365 N for Group 2 and 324 N for Group 3. ANOVA (SPSS) found a significant difference (p < 0.05) between groups. A Scheffe Test revealed a significant difference between Groups 1 and 3. It was concluded that increasing the cement thickness above 70 microns reduced the fracture strength of porcelain jacket crowns.

A ferrule is a metal ring or cap used to strengthen the end of a stick or tube. It has been proposed that the use of a ferrule as part of the core or artificial crown may be of benefit in reinforcing root-filled teeth. A review of the literature investigating this effect is presented. The literature demonstrates that a ferrule effect occurs owing to the artificial crown bracing against the dentine extending coronal to the crown margin. Overall, it can be concluded that a ferrule is desirable, but should not be provided at the expense of the remaining tooth/root structure.

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