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This brief introduces a delayed differential feedback chaos generator with a programmable feedback element. The programmable feedback allows us to implement an arbitrary nonlinearity or modulate the feedback delay time. Delayed differential feedback systems have been suggested for secure communications, and the flexibility of the programmable system is shown to enhance security against published cracking algorithms. [ABSTRACT FROM AUTHOR]

The aim of this study was to test the feasibility of employing clinical visual examination at the D1 (enamel and dentine caries) diagnostic threshold, fibre-optic transillumination (FOTI), elective temporary tooth separation (ETTS) and electronic caries measurement (ECM) in the environment of an epidemiological study or clinical trial. It also aimed to compare the diagnostic yield of these diagnostic aides and methods. The sample consisted of 182 Latvian children, mean age 13.3 years (range = 10.6-15.7). For 12-year-old subjects the mean D3MFS was 10.58 (SD 6.05) and the mean D1MFS was 19.97 (SD 10.47). The additional diagnostic yield from FOTI examination of approximal sites was 40.0% at the D1 threshold. The additional apparent yield for ETTS was 52.8% at the D1 threshold. ETTS detected 38.3% more carious surfaces than FOTI at the D1 threshold. Conversely 57 surfaces thought to be carious on FOTI examination were judged sound following ETTS. Although the ECM appeared practical to use, it broke early in the trial and the results obtained prior to breappeared inaccurate. In conclusion, all diagnostic methods were feasible under the conditions of an epidemiological study or clinical trial. [ABSTRACT FROM AUTHOR]

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Sulcular bleeding after stimulation with a periodontal probe has been associated with the presence of an inflammatory lesion in the gingiva. The objective of this study was to evaluate the effect of the placement of the probe in relation to the tooth surface, and the effect of standardising the probing pressure on the intra- and inter-examiner reproducibility of the gingival bleeding when using a well-defined bleeding index. Four different variations were define: parallel bleeding index (ParBI): when the probe is run along the marginal gingiva it is held parallel to the tooth surface. Angulated bleeding index (AngBI): the probe is held at an angle of approximately 60 to the Inogitudinal axis of the tooth and in contact with the sulcular epithelium. Controlled force parallel bleeding index (CF-ParBI)/controlled force angulated bleeding index (CF-AngBI): the same procedure as described for the ParBI and AngBI is followed, but instead of a conventional (WHO-ASH/Dentsply®) probe an adjustable force probe (Brodontic®-ASH/dentsply), adjusted to 0.25 N is used. The results show that the agreement both within and between clinicians could hardly be rated as 'fair' on a site basis. Approximately one in every three sites was given a different assessment on the second examination. This might have been the consequence of the repeat examination. Agreement on a quadrant basis was slightly better. Furthermore, the direction of the probing influence the number of provoked bleeding sites. Angulation of the probe produces consistently less bleeding compared with parallel placement of the probe. [ABSTRACT FROM AUTHOR]