Field-induced Stark effects in Ag-coated CdS quantum dot structures are presented. We observe clear exciton peaks due to the quantum confinement effect and the surface plasmon effect in Ag-coated CdS quantum dot fabricated by gamma ray irradiation method. In addition, we observed also a dominant red-shift of the CdS exciton absorption peak as the Wannier Stark effect, implying the strong local field effect in the metal-coated semiconductor composite quantum dot system. The Stark shift of the exciton peak is investigated as a function of the local field for different silver thickness and various sizes of quantum dots based on the effective-mass Hamiltonian using the numerical-matrix-diagonalization method.
The transmission and storage became a major dilemma due to the large size of medical imaging data. Clinical CT scanners typically generate sequential data in each patient. Because there are great correlations between continuous slices in these data, we could investigate a significant breakthrough in data compression applying motion estimation and compensation. With motion vector and motion compensated frame difference, we propose a new approach to encode a compressed sequential stream into DICOM image data structure and it may also be possible to efficiently redesign a multiframe header approach, which could improve compression ratios due to the avoidance of duplicative header information of each DICOM file in the same patient. Motion estimation could be retrieved by block matching approaches on 8x8 blocks of image information. For each 8x8 block, a single motion vector was found by minimizing the mean-square error. The compensation of the estimated motion was presented to smooth out the artifacts along block boundaries. In result, we were able to show the higher compression ratios relative to the output file size and effectively transfer a series of CT images at lower bit rates.