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Digital image processing techniques have wide applications in different scientific fields including the medicine. By use of image processing algorithms, physicians have been more successful in diagnosis of different diseases and have achieved much better treatment results. In this paper, we propose an automatic method for segmenting the skin lesions and extracting features that are associated to them. At this aim, a combination of Speeded-Up Robust Features (SURF) and Active Contour Model (ACM), is used. In the suggested method, at first region of skin lesion is segmented from the whole skin image, and then some features like the mean, variance, RGB and HSV parameters are extracted from the segmented region. Comparing the segmentation results, by use of Otsu thresholding, our proposed method, shows the superiority of our procedure over the Otsu theresholding method. Segmentation of the skin lesion by the proposed method and Otsu thresholding compared the results with physician's manual method. The proposed method for skin lesion segmentation, which is a combination of SURF and ACM, gives the best result. For empirical evaluation of our method, we have applied it on twenty different skin lesion images. Obtained results confirm the high performance, speed and accuracy of our method.

We investigate theoretically indirect exchange interaction between magnetic impurities mediated by one-dimensional gapped helical states. Such states, containing massive Dirac fermions, may be realized on the edge of a two-dimensional topological insulator when time-reversal symmetry is weakly broken. We find that the indirect exchange interaction consists of Heisenberg, Dzyaloshinsky-Moriya, in-plane and out-of-plane Ising terms. These terms decay exponentially when Fermi level lies inside the bandgap whereas the Dzyaloshinsky-Moriya term has smallest amplitude. Outside the energy gap the massive helical states modify oscillatory behaviors of the range functions so that their periods decrease near the edge of band in terms of energy gap or Fermi energy. In addition, the out-of-plane Ising term vanishes in the case of zero-gap structure but its oscillation amplitude increases versus energy gap and decreases as a function of Fermi energy whereas the oscillation amplitudes of other components remain constant. Analytical results are also obtained for subgap and over gap regimes. Furthermore, the effects of electron-electron interactions are analyzed., Comment: 8 pages, 4 figures

A vertical connection of water is formed when a high voltage electrode is dipped in and pulled out of a container of deionized water. We considered the formation and dynamical characteristics of this vertical water bridge. For the first time in this field, instabilities were observed in the bridge that led to an oscillatory behaviour which we categorized them into three dynamical regimes. some explanations were supplied on the physics behind these dynamics. We report the formation of macroscopic droplets during our experiments, which their dynamics revealed that they are electrically charged. In some cases the droplets levitated in the air due to the equality of gravity and electrical force (acting in the opposite direction). Our results shed light on the physics behind this phenomenon and the horizontal water bridge, which explanations regarding its underlying physics have led to controversial theories and discussions before., Comment: 8 pages, 5 figures, 5 supplementary videos