In this paper, a novel arrangement for quantizer levels in the Quantization Index Modulation (QIM) method is proposed. Due to perceptual advantages of logarithmic quantization, and in order to solve the problems of a previous logarithmic quantization-based method, we used the compression function of mu-Law standard for quantization. In this regard, the host signal is first transformed into the logarithmic domain using the mu-Law compression function. Then, the transformed data is quantized uniformly and the result is transformed back to the original domain using the inverse function. The scalar method is then extended to vector quantization. For this, the magnitude of each host vector is quantized on the surface of hyperspheres which follow logarithmic radii. Optimum parameter mu for both scalar and vector cases is calculated according to the host signal distribution. Moreover, inclusion of a secret key in the proposed method, similar to the dither modulation in QIM, is introduced. Performance of the proposed method in both cases is analyzed and the analytical derivations are verified through extensive simulations on artificial signals. The method is also simulated on real images and its performance is compared with previous scalar and vector quantization-based methods. Results show that this method features stronger a watermark in comparison with conventional QIM and, as a result, has better performance while it does not suffer from the drawbacks of a previously proposed logarithmic quantization algorithm.

This study tested the hypothesis that adolescents with attention deficit hyperactivity disorder (ADHD) exhibit a higher prevalence of caries than adolescents in a control group. Thirty-two adolescents with ADHD and a control group of 55 adolescents from a population-based sample, all 17 yr of age, underwent a clinical and radiographic dental examination. The mean ± SD number of decayed surfaces (DS) was 2.0 ± 2.2 in adolescents with ADHD and 0.9 ± 1.4 in adolescents of the control group. Thirty-one per cent of the adolescents in the ADHD group had no new caries lesions (DS = 0) compared with 62% in the control group. Six per cent of the adolescents in the ADHD group were caries free [decayed, missing or filled surfaces (DMFS) = 0] compared with 29% in the control group. Adolescents with ADHD also had a higher percentage of gingival sites that exhibited bleeding on probing compared with the control group: 35 ± 39% vs. 16 ± 24% (mean ± SD), respectively. At 17 yr of age, adolescents with ADHD exhibited a statistically significantly higher prevalence of caries compared with an age-matched control group. Adolescents with ADHD need more support regarding oral hygiene and dietary habits. They should be followed up with shorter intervals between dental examinations to prevent caries progression during adulthood.

A Multiplicative Patchwork Method (MPM) for audio watermarking is proposed in this paper. In order to embed watermark data within the host signal, two subsets of the host signal features are selected using two secret keys. Then, watermark data is inserted simply by multiplying one subset and leaving the other one unchanged. In order to have an error free detection in attack-free case, embedding is performed in the selected frames of the host signal which satisfies a certain condition. This method is implemented in the wavelet domain and approximation coefficients are used for data embedding. Furthermore, the inaudibility of watermark insertion is controlled using iterative approach aided by Perceptual Evaluation of Audio Quality (PEAQ) algorithm. Probability of error is derived and the validity of the analytical derivation is verified by simulation. Experimental results show that MPM is more robust than the previous patchwork methods against common attacks such as noise, filtering, MP3 compression, etc. Index Terms-Digital watermarking, Multiplicative PatchworkMethod (MPM), ratio distribution, discrete wavelet transform

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Shielding failure has long been recognized as a possible mode of lightning flashover. This paper reports the development of a method for estimating the shielding failure number of transmission lines using the charge simulation method. The effects of towers, sags of conductors, and a perfectly conducting ground are represented in 3-D computation. In addition, the stepwise descending nature of a downward negative leader-streamer system is taken into account by using an appropriate progression model. Upward leader inception and propagation is also modeled utilizing critical equivalent streamer-length criterion as well as Rizk's formula. The results of the comparison between traditional and proposed techniques with different criteria are also presented.Index Terms-Charge simulation method (CSM), leader, shielding failure number (SFN), transmission line.

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