Three-dimensional oscillator in magnetic field: the de Haas-van Alphen effect in mesoscopic systems

The theoretical investigation of the cluster de Haas - van Alphen (dHvA) oscillations in three-dimensional systems performed for the first time. Applying a three-dimensional oscillator model to systems with electron numbers $10< N \leq 10^5$ we predict distinctive size effects: the dHvA oscillations can be observed only within a certain temperature range determined by $N$; the lower size limit for $N$ is $\approx 20$; the amount of the dHvA oscillations is reduced with decreasing $N$ which is accompanied by stretching the period of the oscillations.Comment: 14 pages, 6 figure

Variability of Two Plaque Sampling Methods in Quantitation of <i>Streptococcus mutans</i>

The aim of this study was to determine the reproducibility of individual versus pooled plaque sampling of permanent first molars (PFM) to quantitate Streptococcus mutans (SM)/total streptococci (TS). Ten individual and pooled plaque samples were collected from 35 subjects, randomly assigned to individual-first or pooled-first group. Plaque samples were processed and quantified for SM and TS. SM/TS ratio was used to determine the reproducibility within two group samples. Mean percentage of SM/TS in both methods were not significantly different. However, within subject detection of SM was found to be significantly more sensitive for individual sampling method. Despite the lack of a difference between both methods for SM/TS quantitation, the difference in SM detection suggests that individual sampling is more sensitive

Dental caries, gingival health, and oral hygiene of long term survivors of paediatric malignant diseases.

Fifty two children who had had cancer and been treated with chemotherapy, and who were long term event free, were examined for caries prevalence, gingival health, and oral hygiene and compared with a control group. A higher dental caries prevalence for the 14-17 year age group was noted. The restorative index was significantly lower in the age group 10-13. There were no significant differences in gingival index, plaque index, or toothbrushing frequency. It is concluded that these patients should be considered as at high risk for caries after cancer treatment. Professional dental follow up should be integrated in the medical follow up