一种多路访问多星型冲突避免高速局域网协议

提出了一种采用避免冲突开关的多路访问多星型高速局域网协议。协议分析比较结果表明,其性能优于许多现有的LAN协议,适合于综合业务高速局域网。

多星形结构的移动传输网电路收敛方案

文章首先分析了移动传输的逻辑结构与物理结构的矛盾,提出了两种解决办法并作了比较,然后分析了它们的优点,最后提出了相应的实施方案。

Variable expression of cystatin C in cultured trans-differentiating rat hepatic stellate cells

AIM. To study the expression of cystatin C （CysC）, its regulation by transforming growth factor-β1 （TGF-β1） and platelet-derived growth factor （PDGF） and the potential interference of CysC with TGF-β1 signaling in this special cell type. METHODS： We evaluated the CysC expression in cultured, profibrogenic hepatic stellate cells and transdifferentiated myofibroblasts by Northern and Western blotting and confocal laser scanning microscopy. RESULTS： CysC was increased significantly in the course of trans-differentiation. Both TGF-β1 and PDGFBB suppressed CysC expression. Furthermore, CysC secretion was induced by the treatment with TGF-β1. Although CysC induced an increased binding affinity of TGF-β receptor type Ⅲ （beta-glycan） as assessed by chemical cross-linking with [^125I]-TGF-β1, it did not modulate TGF-β1 signal transduction as shown by evaluating the Smad2/3 phosphorylation status and [CAGA]-MLP-luciferase reporter gene assay. Interestingly, the shedding of type Ⅲ TGF-β receptor beta-glycan was reduced in CysC-treated cells. Our data indicated that CysC expression was upregulated during transdifferentiation. CONCLUSION： Increased CysC levels in the serum of patients suffering from liver diseases are at least partially due to a higher expression in activated hepatic stellate cells. Furthermore, TGF-β1 influences the secretion of CysC, highlighting a potentially important role of cysteine proteases in the progression of hepatic fibrogenesis.

A Multi-parameter Model for Radio Dichotomy of Active Galactic Nuclei and Jets

Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is studied. It turns out that radio-loudnees of AGNs couM be governed by five parameters： （i） the BH spin, （ii） a power-law index of the variation of the magnetic field on the disc; （iii） a parameter determining the position of the inner edge of the disc, （iv） the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and （v） the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.

Brazilian Buffalo Genetic Variability by Cross-Specific Microsatellite Set

Buffaloes （Bubalus bubalis） are widely distributed and were introduced to Brazil in 1895. Most of the molecular genetic characterization of buffaloes has been done with cross-specific （cattle） markers, but few of them include Brazilian populations. Nineteen commonly used cattle microsatellites were tested to develop a multiplexed set of microsatellites and characterize Brazilian buffalo. Three PCR mixes were finally developed with the 11 markers that succeed in amplify and were polymorphic （58%）. The average number of alleles was 5.42, with an average observed and expected heterocigozity of 0.441 and 0.695, respectively. As it was expected, Brazilian buffalo variability was lower than the previously reported from the domestication centres （China and India）, but higher than the seriously selected European populations. The exclusion power calculated for the eleven markers in Brazilian buffalo was 0.9999999996, this allows its use in DNA based traceability.

Urban landscape classification using Chinese advanced high-resolution satellite imagery and an object-oriented multi-variable model

The Chinese ZY-1 02C satellite is one of the most advanced high-resolution earth observation systems designed for terrestrial resource monitoring. Its capability for comprehensive landscape classification, especially in urban areas, has been under constant study. In view of the limited spectral resolution of the ZY-1 02C satellite （three bands）, and the complexity and hetero- geneity across urban environments, we attempt to test its performance of urban landscape classification by combining a multi- variable model with an object-oriented approach. The multiple variables including spectral reflection, texture, spatial autocorre- lation, impervious surface fraction, vegetation, and geometry indexes were first calculated and selected using forward stepwise linear discriminant analysis and applied in the following object-oriented classification process. Comprehensive accuracy as- sessment which adopts traditional error matrices with stratified random samples and polygon area consistency （PAC） indexes was then conducted to examine the real area agreement between a classified polygon and its references. Results indicated an overall classification accuracy of 92.63% and a kappa statistic of 0.9124. Furthermore, the proposed PAC index showed that more than 82% of all polygons were correctly classified. Misclassification occurred mostly between residential area and barren/farmland. The presented method and the Chinese ZY-1 02C satellite imagery are robust and effective for urban landscape classification.

Spatial Dynamics of Cropland and Cropping Pattern Change Analysis Using Landsat TM and IRS P6 LISS III Satellite Images with GIS

The study of the spatial patterns and temporal changes of cropland is important to understand the underlying factors and the functional effects of the agricultural landscape. On the other hand, crop dynamics mapping is essential to know the overall agro-spatial diversity of the area. Therefore, this paper addressed a spatio-temporal analysis of cropland and cropping pattern change in the Bogra district of Bangladesh over the last 16 years （between 1988/89 and 2004/05）. In this paper, crop mapping from multi-temporal and multi-sensor satellite images was described. Landsat TM and IRS P6 LlSS Ⅲ satellite images were used with GIS for spatial dynamics of cropland and cropping pattern change analysis. First, seasonal cropland maps were derived from object-based classification of satellite images, then two-date classified image differencing with GIS overlay technique and decision rules were applied. Cropping pattern change was analyzed in a spatial and quantitative way for the 16 years and for this, Integrated Land and Water Information System （ILWIS） and Land Change Modular （LCM） of IDRISl Andes were used. The results showed that in the area, mono crop cultivation was found in summer, but in winter, areas under different crop cultivation had changed dramatically. Change analysis showed that the changes mainly occurred in the north northwest and southwest of the areas, and during the time the highest change area was found under the rice-potato pattern.