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Objective. Multi-contrast magnetic resonance (MR) imaging super-resolution (SR) reconstruction is an effective solution for acquiring high-resolution MR images. It utilizes anatomical information from auxiliary contrast images to improve the quality of the target contrast images. However, existing studies have simply explored the relationships between auxiliary contrast and target contrast images but did not fully consider different anatomical information contained in multi-contrast images, resulting in texture details and artifacts unrelated to the target contrast images. Approach. To address these issues, we propose a dual contrast attention-guided multi-frequency fusion (DCAMF) network to reconstruct SR MR images from low-resolution MR images, which adaptively captures relevant anatomical information and processes the texture details and low-frequency information from multi-contrast images in parallel. Specifically, after the feature extraction, a feature selection module based on a dual contrast attention mechanism is proposed to focus on the texture details of the auxiliary contrast images and the low-frequency features of the target contrast images. Then, based on the characteristics of the selected features, a high- and low-frequency fusion decoder is constructed to fuse these features. In addition, a texture-enhancing module is embedded in the high-frequency fusion decoder, to highlight and refine the texture details of the auxiliary contrast and target contrast images. Finally, the high- and low-frequency fusion process is constrained by integrating a deeply-supervised mechanism into the DCAMF network. Main results. The experimental results show that the DCAMF outperforms other state-of-the-art methods. The peak signal-to-noise ratio and structural similarity of DCAMF are 39.02 dB and 0.9771 on the IXI dataset and 37.59 dB and 0.9770 on the BraTS2018 dataset, respectively. The image recovery is further validated in segmentation tasks. Significance. Our proposed SR model can enhance the quality of MR images. The results of the SR study provide a reliable basis for clinical diagnosis and subsequent image-guided treatment. [ABSTRACT FROM AUTHOR]

This is an examination of the determinants of corporate bond credit spreads using both weekly and monthly option-adjusted spreads for nine Merrill Lynch corporate bond indexes from January 1997 through [...]

We report on the implementation of a confocal microscopy system based on an injection-seeded terahertz parametric generator working at 1.76 THz. The system has a fairly reliable long-term stable operation with pulse energy fluctuations <5 %. We experimentally demonstrate a subwavelength lateral resolution of 158 μm, corresponding to 0.93λ. We also demonstrate the capability of resolving overlapping objects at the different longitudinal surfaces by imaging a designed sample. This is the first detailed demonstration of confocal microscopy based on a THz parametric source, which is helpful for the practical application of THz imaging technology. [ABSTRACT FROM AUTHOR]