Improved target detection method for space-based optoelectronic systems.

The detection of faint and small targets by space-based surveillance systems is difficult owing to the long distances, low energies, high speeds, high false alarm rates, and low algorithmic efficiencies involved in the process. To improve space object detection and help prevent collisions with critical facilities such as satellites, this study proposes an improved method for the detection of faint and small space-based targets. The proposed method consists of two components: star atlas preprocessing and space-based target detection. The star atlas preprocessing step applies multi-exposure image pyramidal weighted fusion to the original image containing the faint and small space-based target. After obtaining the image pyramidal weighted fusion result atlas, the algorithm employs threshold segmentation to improve the overall image clarity, highlight image details, and provide additional information for target detection. The detection of targets partially relies on the local symmetry of the image. Accordingly, a diffusion function describing the local symmetry is established to precisely locate stars by measuring the symmetry factor in a small area surrounding each pixel in the star atlas. This effectively removes the background stars while retaining high-definition and high-contrast images. The efficacy of the algorithm is validated using simulated datasets consisting of space-based and real images. The results demonstrate that the proposed technique improves the applicability of the multistage hypothesis testing (MHT) method in the context of a complex space environment, thus improving the performance of the space-based electro-optical detection system to better catalogue, identify, and track space targets.

Constraint Mechanism of Power Device Design Based on Perovskite Quantum Dots Pumped by an Electron Beam.

This paper studied the constraint mechanism for power device design based on perovskite quantum dots pumped by an electron beam. Combined with device designing, an experimental system of self-saturation luminescence and aging failure was designed for CsPbBr3 films. On this basis, we further completed the self-saturation luminescence and aging failure experiment and constructed a model of self-saturation luminescence and aging failure for CsPbBr3 device designing. Three constraints were proposed after analyzing and discussing the experimental data. Firstly, too high of a pumping current density makes it difficult to effectively promote the enhancement of luminescence efficiency. Secondly, radiation decomposition and aging failure of CsPbBr3 films are mainly related to the polarized degree of CsPbBr3 nanocrystals. Thirdly, by increasing the pumping electric field, the pumping energy can be effectively and widely delivered to the three-dimensional quantum dots film layer space, and there is a nonlinear relationship between the attenuation of the pumping energy density and the increment of the pumping electric field, which will effectively avoid the local high-energy density of instantaneous optical pumping.

Image denoising and enhancement strategy based on polarization detection of space targets.

Polarization detection of space targets is one of the most important research directions in the field of space target recognition. In view of the fact that there are problems such as strong background noise and inconspicuous details of contour features in the polarization image of space targets, an image denoising and enhancement strategy is proposed. To solve the problem of high intensity of Gaussian noise in degree of polarization (DoP) images, a denoising method named adaptive noise template prediction (ANTP) is proposed to eliminate the noise. Compared to the existing methods, the ANTP algorithm performs better at reducing noise and improving image quality. Aiming at the difficulty of separating the background noise from angle of polarization (AoP) images, a denoising method named gray analysis of local area (GALA) is proposed. Compared to traditional methods, the GALA algorithm can effectively extract the contour features of targets and improve the contrast of AoP images. An image fusion method based on discrete cosine transform and local spatial frequency (LSF) is used to fuse the denoised DoP image and AoP image. The experimental results of the simulated and real space target polarization detection confirm the effectiveness of our proposed strategy.

Effect of variation in RANTES promoter on serum RANTES levels and risk of recurrent wheezing after RSV bronchiolitis in children from Han, Southern China.

To investigate the association among RANTES (regulated on activation normal T cell expressed and secreted) gene promoter polymorphism, serum RANTES levels, and recurrent wheezing after RSV (respiratory syncytial virus) bronchiolitis in children (1-12 months of age) from Han, Southern china. Three hundred twenty children with RSV bronchiolitis and 272 controls were enrolled in the 3-year follow-up study. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP), enzyme-linked immunosorbent assay (ELISA) kit and luciferase analysis were the mainly used methods, which were used to genotype the RANTES (-403 G/A), assess the serum RANTES levels and the RANTES promoter activity. As the results showed, the RANTES (-403 G/A) in the promoter region was associated with recurrent wheezing after RSV bronchiolitis (p < 0.05) and serum RANTES levels (RANTES genotype G/G: 26.03 +/- 7.46 ng/ml G/A: 28.22 +/- 6.44 ng/ml A/A: 30.12 +/- 5.88 ng/ml). Functional analyses of RANTES promoter activity indicated that the RANTES (-403 G to A) mutation increases the transcriptional activity of the RANTES promoter. In conclusion, the RANTES (-403 G/A) polymorphism increases RANTES transcriptional activity resulted in a high serum RANTES levels, thus increased the risk of recurrent wheezing after RSV bronchiolitis.

[The correlation factor about respiratory syncytial virus bronchiolitis and post-bronchiolitis wheezing in infant].

OBJECTIVE: To observe the correlation factor about early-life RSV bronchiolitis and sequential recurrent wheezing for two years. METHODS: Follow up the RSV bronchiolitis patients for two years in order to analyze the occurrence of wheezing post-bronchiolitis. Single and multiple logistic regression analysis were used to determined the risk factors such as individual atopy history and familial atopy history, pet feeding, breast milk, secondhand smoke for RSV bronchiolitis and subsequent wheezing. RESULTS: (1) Not breast feeding, exposure to cigarette smoke and the deficiency of VitA, D were the significant risk factors contributed to the RSV branchiolitis. (2) Exposure to cigarette smoke, the deficiency of VitA, D, the personal history of atopy and the family history of atopy were the significant risk factors contributed to the post-bronchiolitis wheezing in children. (3) Those patients who eosinophilia, high serum IgE, RANTES and decreased TH1 to TH2 Ratio were more likely to have wheezing after RSV bronchiolitis. CONCLUSION: (1) Not breast feeding, exposure to cigarette smoke and the deficiency of VitA, D were the significant risk factors contributed to the RSV bronchiolitis. (2) Exposure to cigarette smoke, the deficiency of VitA, D, the personal history of atopy and the family history of atopy were the significant risk factors contributed to the post-bronchiolitis wheezing in children.

[Association of RANTES gene promoter -28C/G polymorphism with respiratory syncytial virus bronchiolitis].

OBJECTIVE: Respiratory syncytial virus (RSV) infects nearly all children under two years of age. It is poorly understood why a few children who were infected with RSV develop bronchiolitis that require hospital admission while most have a relatively minor illness. Several recent studies have obtained some indications for the involvement of genetic heterogeneity in RSV bronchiolitis, implying that the clinical outcome of RSV infection perhaps is determined by genetic factors. Regulated on activation, normal T cell expressed and secreted RANTES plays a key role in the pathophysiology of RSV bronchiolitis. The purpose of this study was to explore the genetic association between the RANTES gene promoter -28C/G polymorphism and RSV bronchiolitis in Chinese Han ethnic group population. METHODS: The study recruited 238 hospitalized patients (186 male and 52 female) under 12 months of age, with a clinical diagnosis of bronchiolitis due to RSV, the sex, age, hospital stay, SaO2 at the time of admission, personal and family history of atopy were recorded. The 288 healthy control subjects (206 male and 82 female), who had no evidence of personal or familial history of atopy and no history of wheezing, were chosen at the same time. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to identify the polymorphism at position -28C/G of the RANTES promoter. The total IgE concentrations in serum samples were measured by enzyme-linked immunosorbent assay (ELISA). The absolute peripheral blood eosinophil counts were measured by using an automated hematology analyzer. RESULTS: The distribution of RANTES -28C/G gene polymorphism was in accordance with Hardy-Weinberg equilibrium. Compared to control subjects, significant difference was demonstrated for genotypes and allele frequencies of the RANTES -28C/G polymorphism in patients with RSV bronchiolitis (G = 10.22, P < 0.01; chi2 = 9.708, P < 0.01). Compared with the wild type CC, the -28G allele carriers demonstrated a 2.09-fold increased risk of RSV bronchiolitis (OR = 2.09, 95% CI = 1.32 - 3.30, P < 0.01). Interestingly, both the percentage of personal history of atopy and the percentage of family history of atopy for the -28G allele carriers were significantly higher (P < 0.05) than that for those CC homozygotes carriers in RSV bronchiolitis. Compared with the wild type CC, the -28G allele carriers demonstrated a 1.85-fold increased risk of the personal history of atopy (OR = 1.85, 95% CI = 1.01 - 3.38, P = 0.045) and a 1.91-fold increased risk of the family history of atopy (OR = 1.91, 95% CI = 1.03 - 3.54, P = 0.037), and the absolute peripheral blood eosinophil counts for the -28G allele carriers were significantly higher (P < 0.05). CONCLUSION: The RANTES gene promoter -28C/G polymorphism is associated with the susceptibility to RSV bronchiolitis, and the -28G allele is an important predisposing factor for the personal history of atopy and the family history of atopy in RSV bronchiolitis.

[Association between interleukin-8 gene-251 locus polymorphism and respiratory syncytial virus bronchiolitis and post-bronchiolitis wheezing in infants].

OBJECTIVE: Respiratory syncytial virus (RSV) infects nearly all children under two years of age. It is not understood why some develop serious bronchiolitis. Whether there is a genetic component is not known. The nature of the association between RSV bronchiolitis and subsequent wheezing remains unknown. interleukin-8 (IL-8) is a potent neutrophil chemokine and activator, which plays a role in virus-induced wheezing diseases. The purpose of this study was to assess the genetic association between the IL-8 gene promoter -251A/T polymorphism and RSV bronchiolitis and post-bronchiolitis wheezing in children. METHODS: Totally 320 children who were hospitalized for bronchiolitis together with positive immunofluorescence for RSV were recruited in this study from Jan. 2002 to Jan. 2004. A group of 272 healthy children were enrolled as controls. The age of these children ranged from 1 to 12 months. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to identify the polymorphism at position-251 of the IL-8 promoter in RSV bronchiolitis and control groups. The total IL-8 and IgE concentrations in serum samples were measured by enzyme-linked immunosorbent assay (ELISA). The patients with RSV bronchiolitis were followed up in order to analyze the occurrence of wheezing post-bronchiolitis. RESULTS: (1) Both A allele and T allele were detected at -251 of the IL-8 promoter; the prevalence of the A allele in RSV bronchiolitis group was 45.6%, as compared with 37.7% in normal group. The prevalence of IL-8-251A allele was significantly different between the two groups (P < 0.05). (2) For genotypes T/T, A/T, A/A in RSV bronchiolitis, level of serum IL-8 were (17 +/- 6) ng/L, (21 +/- 7) ng/L, (24 +/- 9) ng/L, respectively, the difference was significant among the three genotypes (P < 0.01). (3) The prevalence of the A allele in the group who wheezed after the episode of RSV bronchiolitis was 54.6%, as compared with 35.8% in the group who had bronchiolitis but did not go on to wheeze. The prevalence of IL-8-251A allele was significantly different between the two groups (P < 0.05). CONCLUSION: Polymorphism of IL-8 promoter-251A/T was associated with susceptibility to RSV bronchiolitis in children. The association of IL-8-251A with severe RSV bronchiolitis is most marked in the children who go on to wheeze.