Full-field strain of regenerated bone tissue in a femoral fracture model.

The mechanical behaviour of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X-ray Computed Tomography (XCT) has been extensively used to assess the progress of mineralised tissues in regeneration and when combined with in situ mechanics and digital volume correlation (DVC) has been proven a powerful tool to understand the mechanical behaviour and full-field three-dimensional (3D) strain distribution in bone. The purpose of this study is therefore to use in situ XCT mechanics and DVC to investigate the strain distribution and load-bearing capacity in a regenerating fracture in the diaphyseal bone, using a rodent femoral fracture model stabilised by external fixation. Rat femurs with 1 mm and 2 mm osteotomy gaps were tested under in situ XCT step-wise compression in the apparent elastic region. High strain was present in the newly formed bone (εp1 and εp3 reaching 29 000 µÎµ and -43 000 µÎµ, respectively), with a wide variation and inhomogeneity of the 3D strain distribution in the regenerating tissues of the fracture gap, which is directly related to the presence of unmineralised tissue observed in histological images. The outcomes of this study will contribute in understanding natural regenerative ability of bone and its mechanical behaviour under loading.

Detection and tracking of sea-surface targets in infrared and visual band videos using the bag-of-features technique with scale-invariant feature transform.

Sea-surface targets are automatically detected and tracked using the bag-of-features (BOF) technique with the scale-invariant feature transform (SIFT) in infrared (IR) and visual (VIS) band videos. Features corresponding to the sea-surface targets and background are first clustered using a training set offline, and these features are then used for online target detection using the BOF technique. The features corresponding to the targets are matched to those in the subsequent frame for target tracking purposes with a set of heuristic rules. Tracking performance is compared with an optical-flow-based method with respect to the ground truth target positions for different real IR and VIS band videos and synthetic IR videos. Scenarios are composed of videos recorded/generated at different times of day, containing single and multiple targets located at different ranges and orientations. The experimental results show that sea-surface targets can be detected and tracked with plausible accuracies by using the BOF technique with the SIFT in both IR and VIS band videos.

Adaptive enhancement of sea-surface targets in infrared images based on local frequency cues.

Image enhancement is an important preprocessing step of infrared (IR) based target recognition and surveillance systems. For a better visualization of targets, it is vital to develop image enhancement techniques that increase the contrast between the target and background and emphasize the regions in the target while suppressing noises and background clutter. This study proposes what we believe to be a novel IR image enhancement method for sea-surface targets based on local frequency cues. The image is transformed blockwise into the Fourier domain, and clustering is done according to the number of expected regions to be enhanced in the scene. Based on the variations in the elements in any cluster and the differences between the cluster centers in the frequency domain, two gain matrices are computed for midfrequency and high frequency images by which the image is enhanced accordingly. We provide results for real data and compare the performance of the proposed algorithm through subjective and quantitative tests with four different enhancement methods. The algorithm shows a better performance in the detail visibility of the target.

Localization of myocilin/trabecular meshwork--inducible glucocorticoid response protein in the human eye.

PURPOSE: To study distribution and cellular localization of myocilin/trabecular meshwork-inducible glucocorticoid response protein (TIGR) in the human eye. METHODS: A peptide antibody against a portion of the myosin-like domain of myocilin/TIGR was developed. Different ocular tissues from three human donors were investigated by one- and two-dimensional gel electrophoresis and Western blot analysis. Immunohistochemistry was performed on 25 human eyes enucleated because of posterior choroidal melanoma and on 7 normal human donor eyes. RESULTS: By Western blot analysis, a band at approximately 57 kDa was visualized in cornea, trabecular meshwork, lamina cribrosa, optic nerve, retina, iris, ciliary body, and vitreous humor. By immunohistochemistry, immunoreactivity for myocilin/TIGR was observed in cells of the corneal epi- and endothelium and extracellularly in the corneal stroma and sclera. In the trabecular meshwork, cells of the uveal and corneoscleral meshwork were stained, as was the cribriform area directly adjacent to Schlemm's canal. Positive staining was seen in cells of the ciliary epithelium, ciliary muscle, lens epithelium, and in stromal and smooth muscle cells of the iris. Throughout the entire vitreous body, fine filamentous material was positively labeled. In the retina, staining was seen along the outer surface of rods and cones, in neurons of the inner and outer nuclear layer, and in the axons of optic nerve ganglion cells. Optic nerve axons were stained in the prelaminar, laminar, and postlaminar parts of the nerve. In the region of the lamina cribrosa, astrocytes in the glial columns and cribriform plates were positively labeled. CONCLUSIONS: Myocilin TIGR is expressed in almost every ocular tissue. Depending on the respective tissue, it is observed extra- or intracellularly. The presence of myocilin/TIGR in optic nerve axons and lamina cribrosa astrocytes indicates that the trabecular meshwork might not be the only target of abnormal myocilin/TIGR in GLC1A-linked open-angle glaucoma.