ABSTRACT
Image-based target tracking methods rely on continuous image acquisition and post-processing, which will result in low tracking efficiency. To realize real-time tracking of fast moving objects, we propose an image-free target tracking scheme based on the discrete cosine transform and single-pixel detection. Our method avoids calculating all the phase values, so the number of samples can be greatly reduced. Furthermore, complementary modulation is applied to reduce the measurement noise, and background subtraction is applied to enhance the contrast. The results of simulations and experiments demonstrate that the proposed scheme can accomplish the tracking task in a complex background with a sampling ratio of less than 0.59% of the Nyquist-Shannon criterion, thereby significantly reducing the measurement time. The tracking speed can reach 208 fps at a spatial resolution of 128 × 128 pixels with a tracking error of no more than one pixel. This technique provides a new idea for real-time tracking of fast-moving targets.
ABSTRACT
The Raman spectra of PolyA, PolyU and their double-stranded complex were measured, and the spectral changes upon the formation of double-stranded complex were studied. The experimental results show: (1) Under the experimental conditions used in the present work (0.14 mol x L(-1) NaCl, 1 mmol x L(-1) Tris solution, neutral pH and 15 degrees C), PolyU, PolyA and PolyA x PolyU occur as random-coiled, A-single-stranded helical and A-double-stranded helical conformations, respectively. One of the main spectral differences between the latter two conformations and the former one is the Raman band near 814 cm(-1) of ordered structures. Another difference is in the full width at half the maximum (i.e. FWHM) of the band near 1100 cm(-1). The FWHM of the band 1100 cm(-1) of PolyA is the same as that of PolyA x PolyU, while the band of PolyU shows remarkable broadening. In addition, we found that the conformation of PolyA is somewhat not so ordered as that of its duplex, which can be concluded from the value of I814/I1100 of the two polynucleotides. (2) The formation of duplex makes base-base stacking interactions much stronger, and the conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some corresponding band shift. In this process, PolyU underwent more significant spectral changes than PolyA. As spectral markers, these results can be of great importance in Raman spectral signal detection of gene-chips.
