Bayesian scale space analysis of temporal changes in satellite images

We consider the detection of land cover changes using pairs of Landsat ETM+ satellite images. The images consist of eight spectral bands and to simplify the multidimensional change detection task, the image pair is first transformed to a one-dimensional image. When the transformation is non-linear, the true change in the images may be masked by complex noise. For example, when changes in the Normalized Difference Vegetation Index is considered, the variance of noise may not be constant over the image and methods based on image thresholding can be ineffective. To facilitate detection of change in such situations, we propose an approach that uses Bayesian statistical modeling and simulation-based inference. In order to detect both large and small scale changes, our method uses a scale space approach that employs multi-level smoothing. We demonstrate the technique using artificial test images and two pairs of real Landsat ETM+satellite images.     

前列腺癌发病机制中雄激素和雄激素受体信号的作用

雄激素和雄激素受体(AR)信号在前列腺发育和腺体内环境的稳定中是必要的。AR信号几乎驱动着所有前列腺癌细胞的生长。为了驱动前列腺癌生长,在前列腺癌细胞中的AR信号功能得到完好的保留,所以,在转移性前列腺癌中的雄激素和AR信号作用得到了良好地证明。虽然雄激素和AR信号密切参与着正常前列腺的发育和晚期前列腺癌的转移,但是否雄激素和AR信号也参与了前列腺癌的发生和增殖的早期阶段,这一过程依然不明确。本文综述了前列腺组织中雄激素和AR信号的作用,以及前列腺癌从发生到转移至去势抵抗的知识,并阐述了雄激素和AR在前列腺癌启动的早期阶段中的潜在作用。     

基于压缩感知的智能天线DO A估计算法

波达方向（direction of arrival，DOA）估计是利用具有一定空间结构的天线阵元对空间信源的来波方向进行估计。为解决MUSIC算法和ESPRIT算法在智能天线DOA估计中空间谱分辨率和抗噪声性能方面的不足，依据压缩感知理论的贪婪算法思想，将匹配追踪（matching pursuit，MP）算法和子空间追踪（subspace pursuit，SP）算法应用在DOA估计中，即提出2种新的算法MP-DOA和SP-DOA。这2种算法主要包括原子库建立、信号投影、最佳匹配原子筛选及信号特征提取等过程。4种算法的仿真实验与对比分析结果表明，MP-DOA算法在低信噪比情况下较其他3种算法性能更优越，SP-DOA算法在角度分辨率和对信源数的包容方面的性能较其他3种算法优越，也验证了应用压缩感知理论的优越性。