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Objective: The aim of this study was to use fractal dimension (FD) analysis on multidetector CT (MDCT) images for quantifying the morphological changes of the pulmonary artery tree in patients with pulmonary hypertension (PH). Materials and Methods: Fourteen patients with PH and 17 patients without PH as controls were studied. All of the patients underwent contrast-enhanced helical CT and transthoracic echocardiography. The pulmonary artery trees were generated using post-processing software, and the FD and projected image area of the pulmonary artery trees were determined with ImageJ software in a personal computer. The FD, the projected image area and the pulmonary artery pressure (PAP) were statistically evaluated in the two groups. Results: The FD, the projected image area and the PAP of the patients with PH were higher than those values of the patients without PH (p < 0.05, t-test). There was a high correlation of FD with the PAP (r = 0.82, p < 0.05, partial correlation analysis). There was a moderate correlation of FD with the projected image area (r = 0.49, p < 0.05, partial correlation analysis). There was a correlation of the PAP with the projected image area (r = 0.65, p < 0.05, Pearson correlation analysis). Conclusion: The FD of the pulmonary arteries in the PH patients was significantly higher than that of the controls. There is a high correlation of FD with the PAP. Index terms: Computed tomography (CT); Pulmonary hypertension; Fractal dimension

In recent years, azobenzene derivates have received much attention for their potential application in optical data storage, biophotonics, holographic memories and waveguide switches optical sensors, and sensitive optical components from laser damage in both civilian and military applications. Experimental and theoretical studies demonstrate clearly the effect of the sonor-pi-acceptor (D- -A) conjugation on the steady-state and time-resolved PL spectra of azobenzene derivate films in multifarious situations, but comparatively little is concerned about the two-photon absorption and refraction involved in a single benzene ring. Furthermore, the excitation laser source on the azobenzene derivates in some investigations is continuum laser or nanosecond pulsed laser, where it is hard to avoid thermal effect on nonlinear optical (NLO) process produced by these lasers. To explore the origin of the azobenzene derivates' D- -A conjugation-dependent NLO process is a challenging task and has great signicance in describing the molecular structures of these azobenzene nanostructures as well as improving the performance of azobenzene derivates' devices. The D- -A conjugation of azobenzene functional material can be modified by mixing the azobenzene derivates with metal nanoparticles, so it is convenient to study how the D- -A conjugation affects the NLO properties by using the azobenzene derivate-metal composites. In this letter, the D- -A conjugation-dependent NLO absorption and refraction of the two kinds of azobenzene derivates 4-((4'-hydroxybenzene) azo) benzyl acid(BN) and N-(3, 4, 5-octanoxyphnyl)-N'-4-[(4-hydroxyphenyl) azophenyl]1, 3, 4-oxadiazole (AOB-t8) are investigated by Z-scan technology using 32 ps laser pulse width at 532 nm. The azobenzene derivates' surface is modified using the D- -A conjugation control and overcoating Au nanoparticles on the azobenzene derivates; and the Au/AOB-t8 composites, BN and AOB-t8 are characterized by Z-scans and absorption/fluorescence spectrum, and also calculated based on plasma resonance. The third-order NLO susceptibility of AOB-t8 is enhanced as compared with BN due to the growing conjugate chain and the increasingly extended bond. However, the third-order NLO susceptibility of AOB-t8 is decreased in the composite(Au/AOB-t8) for the cooperation of the local field effect induced by the gold nanoparticles and the extended bond of organic molecules. This work may be helpful to the understanding of the physical mechanism of the surface states and the surface-related optical nonlinearity of semiconductor QDs.

The photoconductive properties of MBB-PPV/C60 composite films fabricated by the physical jet deposition (PJD) technique have been studied on the basis of the photoinduced charge transfer process. Under the photoexcitation, the transverse photoconductivity of the composite films is greatly enhanced by 4 orders of magnitude due to the efficient excitation transfer process from MBB-PPV (as donor) to C60 (as acceptor) occurring at the interface, the separation of charges and the existence of in-layer free carriers. The results indicate that the conjugated polymer/fullerene composite films optimized by an appropriate configuration have potential applications in photoelectric devices and photonic fields.

This paper describes a detection framework to find a specific person from different videos by combining movement information with color invariant features. Special color invariant moment features based on color clustering are presented. Similarity measure method based on the color invariant moment descriptors is given. This method is applied in a practical application system and the experimental result demonstrates that the proposed features have a stronger ability of color based image region similarity discriminating than the traditional color features.

Objectives To clarify the relationship between quantitative coronary angiography (QCA) parameters and fractional flow reserve (FFR) for screening out ideal angiographic parameters to predict myocardial ischaemia. Methods The study included 121 lesions with QCA and FFR datas from 106 patients. The lesions were grouped into FFR>0.75 group and FFR≤0.75 group. Assessed parameters by QCA included percentage diameter stenosis, minimum luminal diameter (MLD), percentage area stenosis, minimum luminal area (MLA), reference vessel diameter (RVD) and lesion length (LL). Correlation analysis was used to identify the relationship between QCA parameters and FFR value, and receiver operating characteristic (ROC) curve was used to determine predictors of FFR≤0.75. Results When compared to FFR>0.75 group, FFR≤0.75 group had higher LL (14.8±7.9 mm vs 10.7±5.4 mm, p=0.024), lower MLD (1.47±0.31 mm vs 1.82±0.51 mm, p=0.028), lower RVD (2.30±0. 50 mm vs 2.81±0.64 mm, p=0.036), and lower MLA (2.30±1.50 mm 2 vs 3.60±2.30 mm 2 , p=0.038). By correlation analysis, significant negative correlation between QCA parameters and FFR included LL (r=−0.209, p=0.040), significant positive correlation included MLD (r=0.414, p=0.040), RVD (r=0.303, p=0.000) and MLA (r=0.315, p=0.002). By using a ROC, we identified MLD≥1.6 mm to be the best cut-off value to fit with a FFR>0.75 with sensitivity 63%, specificity 82%, and positive predictive value 96%. Conclusions Anatomic parameters of intermediate coronary lesions by QCA show a moderate correlation to FFR value. MLD by QCA may be used as an alternative to FFR when assessing the need for intervention in intermediate coronary lesions.

On the basis of measurement and theoretical analysis, the linear and nonlinear optical properties of the CdSe quantumn dots with different nanoparticle sizes were investigated. The relation between the nanoparticle size and the absorption peak of CdSe quantumn dots was characterized by UV-VIS-NIR spectroscopy, and the dependence of third-order nonlinear susceptibility of quantumn dots on nanoparticle size was investigated by picosecond Z-scan technique with different excitation wavelengths (532nm and 1064nm,resp.). The analysis of optical properties of the films was carried out using the theory of localized field enhancement. The experimental and theoretical results showed the dependence of third-order nonlinear susceptibilities χ(3) on the CdSe nanoparticle size. With CdSe nanoparticle size around 4.3nm and the excitation wavelength of 532nm, which was close to the resonance, the third-order nonlinear susceptibility χ(3) showed a maximum value of 2.0×10-11 esu.